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LIST  OF  CONTRIBUTORS. 


BUNTING,  RUSSELL  W.,  D.D.Sc. 
CAPON,  WILLIAM  A.,  D.D.S. 
CONZETT,  JOHN  V.,  D.D.Sc. 
COOLIDGE,  EDGAR  D.,  D.D.S. 
HOPEWELL-SMITH,  ARTHUR,  Sc.D.,  M.R.C.S. 
LYONS,  CHALMERS  J.,  D.D.Sc. 
NOYES,  FREDERICK  B.,  B.A.,  D.D.S. 
PRINZ,  HERMANN,  A.M.,  M.D.,  D.D.S. 
THOMA,  KURT  H.,  D.M.D. 
VOLLAND,  ROSCOE  H.,  M.D.,  D.D.S. 
WARD,  MARCUS  L.,  D.D.Sc. 


THE 


AMERICAN  TEXT-BOOK 


OF 


OPERATIVE  DENTISTRY. 


IN  CONTRIBUTIONS  BY  EMINENT  AUTHORITIES 


EDITED  BY 

MARCUS  L.  WARD,  D.D.Sc. 

PKOFESSOR    OF    DENTAL    METALLURGY   AND    CROWN    AND    BRIDGE    WORK,  AND  DEAN    OF  THE 
COLLEGE    OF   DENTAL    SURGERY,    UNIVERSITY    OF    MICHIGAN 


FIFTH  EDITION,  THOROUGHLY  REVISED 


ILLUSTRATED  WITH  762  ENGRAVINGS  AND  A  COLORED  PLATE 


LEA  &  FEBIGER 

PHILADELPHIA   AND  NEW  YORK 
1920 


&l^^JmI!a^ 


Z^-8l0( 


COPYRIGHT 

LEA  &  FEBIGER 
1920 


\ 


WITH  THE  CONSENT  OF  THE  CONTRIBUTORS 

THIS  VOLUME 

IS  DEDICATED  TO  THOSE   WHO   HAVE   AIDED   IN  THE   DEVELOPMENT   OF 

OPERATIVE   DENTISTRY 

TO  WHOM   IT  HAS  NOT   BEEN   POSSIBLE  TO   GIVE   CREDIT 


PREFACE. 


The  demand  for  a  new  edition  of  the  American  Text-book  of  Opera- 
tive Dentistry  has  necessitated  much  more  than  a  mere  revision  of  the 
previous  text.  The  work  has  been  largely  rewritten  and  the  fifth 
edition  is  therefore  practically  a  new  book.  Such  a  radical  change  has 
been  rendered  necessary  by  the  rapid  evolution  which  has  taken  place 
throughout  the  entire  domain  of  the  science  and  art  of  dentistry  since 
the  publication  of  the  previous  edition.  The  accumulation  of  new 
data,  the  investigation  of  the  deeper  problems  of  dental  science,  and  the 
modification  exerted  by  these  factors  upon  the  practice  of  dentistry 
have  wrought  changes  that  in  certain  departments  are  little  less  than 
revolutionary.  So  rapid  and  far-reaching  in  their  effects  are  many  of 
the  changes  which  have  taken  place  that  the  whole  subject  of  operative 
dentistry  has  been  and  still  is  in  a  state  of  flux. 

The  mirroring  of  the  progressive  movement  in  operative  dentistry 
will  be  evident  in  the  plan  as  well  as  in  the  text  of  this  work.  The 
constantly  growing  demand  for  preventive  dentistry  has  made  it 
necessary  to  treat  several  subjects  in  a  much  more  extensive  manner 
than  has  been  done  in  former  editions  in  order  that  the  undergraduate 
student  may  more  intelligently  comprehend  preventive  dentistry  in  its 
relation  to  all  other  operative  procedures. 

It  is  fully  recognized  that  the  scientific  basis  of  many  of  the  subjects 
which  constitute  preventive  dentistry  in  its  broadest  sense  is  much 
more  fully  elaborated  in  the  present  work  than  would  be  justifiable  in 
a  treatise  or  text-book  devoted  exclusively  to  operative  dentistry  as  an 
art;  but  as  there  appears  to  be  a  demand  upon  the  part  of  students  and 
practitioners  for  a  volume  furnishing  a  comprehensive  view  of  the 
fundamental  principles  upon  which  alone  an  intelligent  and  rational 
practice  may  be  based,  the  treatment  of  the  subject  of  operative 
dentistry  in  the  present  work  has  been  extended  to  include  those 
principles. 

Certain  differences  of  opinion  will  be  occasionally  manifest  in  the 
work  in  the  treatment  of  allied  subjects  by  different  authors.  While 
such  differences  are,  of  course,  not  desirable,  and  while  qo  conflict  of 
opinion  will  be  noticed  with  respect  to  established  scientific  principles, 

(ix) 


X  PREFACE 

it  is  manifestly  impossible  to  secure  unanimity  upon  subjects  which 
have  not  as  yet  reached  a  stage  of  development  entitling  them  to 
classification  among  the  exact  sciences,  and  which  are  subject  to  the 
variations  in  methods  of  procedure  of  different  individuals.  For  exam- 
ple, it  will  be  observed  that  all  the  contributors  to  this  work  have  used 
the  nomenclature  advocated  by  Dr.  G.  V.  Black  iti  describing  the  teeth 
and  their  anatomy  except  the  three  who  have  written  chapters  who  are 
associated  with  departments  of  general  and  comparative  anatomy. 
The  latter  have  used  the  words  canine,  premolar,  etc.,  which  appear 
to  some  general  and  comparative  anatomists  as  the  logical  terms, 
while  the  former  have  adhered  to  the  use  of  the  terms  cuspid  and  bicus- 
pid, etc.,  in  accordance  with  more  common  usage.  As  dentistry  con- 
tinues to  develop  as  a  branch  of  medicine,  it  appears  possible  that  the 
opinion  of  the  anatomist  will  prevail  and  some  of  the  terms  now 
generally  used  by  the  dental  profession  to  describe  the  teeth,  and 
which  seem  to  have  been  useful  in  the  development  of  operative 
dentistry,  will  be  displaced  by  terms  more  accordant  with  the  funda- 
mental subjects  of  general  and  comparative  anatomy.  Such  differ- 
ences of  opinion  are  not  at  present  reconcilable,  and  cannot  be,  until 
the  bar  of  professional  judgment  has  decided  which  school  of  thought 
is  based  upon  the  better  observation  and  experience. 

The  progress  in  the  development  of  the  fundamental  principles  and 
technic  of  correcting  mal-occlusion  has  been  so  rapid  that  orthodontia 
has  become  a  specialty  with  a  scope  so  broad  that  it  has  seemed  wise 
to  include  in  this  work  only  the  principles  of  orthodontia  that  a  general 
practitioner  should  know  in  order  to  enable  him  to  advise  intelligently 
those  who  are  in  his  care.  In  submitting  this  work  to  the  critical 
consideration  of  former  contributors  to  the  subject,  fellow-teachers 
and  students,  it  is  the  desire  of  the  editor  to  do  so  with  the  highest 
respect  for  orthodontia  as  a  progressive  and  preventive  measure — his 
only  reason  for  curtailing  the  subject  in  this  volume  being  inability  to 
allow  a  sufficient  space  for  an  appropriate  presentation  of  the  subject 
in  its  present  state  of  development. 

The  progressive  movement  in  operative  dentistry  is  still  further 
reflected  in  the  chapter  on  roentgen  diagnosis.  A  study  of  the  advances 
which  have  taken  place  in  the  field  of  roentgenology  reveals,  besides 
important  additions  to  our  knowledge,  a  vastly  more  important 
advance  manifested  in  a  better  understanding  of  the  value  of  the 
roentgenogram  in  determining  pathologic  conditions,  the  result  being 
more  rational  practice. 

Chapters  XII  and  XIV  are  devoted  to  an  equally  progressive 
development  in  the  discovery  of  new  substitutes  for  cocain  which  are 
less  toxic  and  equally  effective  in  the  removal  of  pain.    With  marked 


PREFACE  XI 

improvement  in  the  technic  of  handling  these  new  products  local 
anesthesia  has  become  much  more  generally  used  by  practitioners  of 
dentistry  than  before.  It  has  been  recognized  that  local  anesthesia 
was  more  desirable  than  any  other  anesthetic  in  many  respects  when  the 
operation  was  to  be  performed  in  the  dental  office  where  it  was  difficult 
to  prepare  the  patient  properly  and  equally  difficult  to  protect  him 
after  the  operation.  Not  until  the  advent  of  the  new  product  novocain 
or  procain,  together  with  improved  technic,  however,  could  local 
anesthesia  be  used  so  satisfactorily  for  so  many  operations,  especially 
the  extraction  of  teeth. 

The  recent  attention  given  to  work  in  cavity  preparation  by  studying 
the  location  and  direction  of  progress  of  caries  and  the  extension  of  the 
cavity  walls  into  relatively  immune  areas  for  caries  prevention  has 
seemed  to  warrant  a  somewhat  lengthy  consideration  of  this  subject, 
first,  because  in.  itself,  it  is  a  preventive  measure,  and  second,  because 
it  has  been  regarded  fundamental  to  all  work  which  involves  restora- 
tions for  lost  tooth  tissue. 

To  have  made  this  work  in  true  monographic  style  with  references 
to  all  of  the  authors  of  every  statement  would  have  resulted  in  a  book 
of  impracticable  size  and  form.  The  policy  that  has  been  adopted 
provides,  as  a  rule,  for  reference  to  authorities  for  facts  that  have  not 
received  general  recognition. 

The  editor  takes  this  occasion  to  express  his  deep  sense  of  apprecia- 
tion of  the  uniform  courtesy  and  spirit  of  helpfulness  which  have 
characterized  the  attitude  of  all  his  collaborators  in  this  work,  and 
their  willingness  to  sacrifice  personal  interests  to  the  thoroughness 
and  accuracy  of  the  work  as  a  whole.  To  express  adequately  my 
appreciation  of  the  generous  support  accorded  by  my  colleagues,  Drs. 
Bunting  and  Lyons  and  Miss  Nita  Faught  and  Miss  Hazel  V.  Kramer 
in  the  preparation  of  this  work  is  not  possible.  Second,  only  to  the 
contributors,  should  these  persons  who  have  been  intimately  asso- 
ciated with  me,  receive  credit  for  any  help  that  this  work  may  be  to 
the  progress  of  dentistry, 

Marcus  L.  Ward. 


LIST  OF  CONTRIBUTORS. 


RUSSELL  W.  BUNTING,  D.D.Sc, 

Professor  of  Dental  Histology  and  Pathology,  University  of  Michigan. 

WILLIAM  A.  CAPON,  D.D.S., 

Assistant  Professor  of  Dental  Ceramics,  The  Thomas  W.  Evans  Museum  and 
Dental  Institute,  School  of  Dentistry,  LTniversity  of  Pennsylvania. 

JOHN  V.  CONZETT,  D.D.Sc, 

Author  of  Many  Valuable  Articles  on  Operative  Dentistry. 

EDGAR  D.  COOLIDGE,  D.D.S., 

Professor  and  Head  of  the  Department  of  Materia  Medica  and  Therapeutics, 
University  of  Illinois. 

ARTHUR  HOPEWELL-SMITH,  Sc.D.,  L.D.S.,  M.R.C.S.,  L.R.C.P., 

Professor  of  Dental  Histology,  Histopathology  and  Comparative  Odontology, 
The  Thomas  W.  Evans  Museum  and  Dental  Institute,  School  of  Dentistry, 
University  of  Pennsylvania. 

CHALMERS  J.  LYONS,  D.D.Sc, 

Professor  of  Oral  Surgery  and  Consulting  Dental  Surgeon  to  the  University 
Hospital,  University  of  Michigan. 

FREDERICK  B.  NOYES,  B.A.,  D.D.S., 

Professor  and  Head  of  the  Department  of  Orthodontia  and  Dental  Histology, 
University'  of  Illinois. 

HERMANN  PRINZ,  A.M.,  M.D.,  D.D.S., 

Professor  of  Materia  Medica  and  Therapeutics,  The  Thomas  W.  Evans  Museum 
and  Dental  Institute,  School  of  Dentistry,  University  of  Pennsylvania. 

KURT  H.  THOMA,  D.M.D., 

Lecturer  on  Oral  Histology  and  Pathology,  Harvard  University. 

ROSCOE  H.  VOLLAND,  M.D.,  D.D.S., 

Professor  of  Oral  Pathology  and  Operative  Technic,  Iowa  University. 

MARCUS  L.  WARD,  D.D.Sc, 

Professor  of  Dental  Metallurgy  and  Crown  and  Bridge  Work,  Dean,  College 
of  Dental  Surgery,  University  of  Michigan. 


CONTENTS. 


CHAPTER  I. 


THE  ANATOMY  OF  THE  TEETH  OF  MAN 17 

By  Arthur  Hopewell-Smith,  Sc.D.,  L.D.S.,  M.R.C.S.,  L.R.C.P. 

CHAPTER  II. 

DENTAL     HISTOLOGY     WITH     REFERENCE     TO     OPERATIVE 

DENTISTRY 51 

By  Frederick  B.  Noyes,  B.A.,  D.D.S. 

CHAPTER  III. 
PREVENTIVE  DENTISTRY 122 

By  Russell  W.  Bunting,  D.D.Sc. 

CHAPTER  IV. 

INSTRUMENTATION,  CAVITY  PREPARATION,  AND  THE  FILLING 
OF  TEETH  WITH  GOLD  FOIL,  GOLD  INLAYS,  AMALGAM, 
CEMENTS  AND  GUTTA-PERCHA 179 

By  John  V.  Conzett,  D.D.Sc,  and  Roscoe  H.  Voll.\nd,  M.D.,  D.D.S. 

CHAPTER  V. 

GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 284 

By  Marcus  L.  Ward,  D.D.Sc. 

CHAPTER  VI. 

HIGH  FUSING  PORCELAIN  INLAYS 299 

By  WILLM.M  A.  Capon,  D.D.S. 

CHAPTER  VII. 

PROPERTIES  OF  FILLING  MATERIALS 339 

By  Marcus  L.  Ward,  D.D.Sc. 

CHAPTER  VIII. 

THERAPEUTIC      PROCEDURES      IN      THE      TREATMENT      OF 

INFECTED   ROOT    CANALS 411 

By  HER^LVN  Prinz,  A.M.,  M.D.,  D.D.S. 


XVI  CONTENTS 


CHAPTER  IX. 

THE  PREPARATION  AND  FILLING  OF  ROOT  CANALS        .      .      .     431 
By  Edgar  D.  Coolidge,  D.D.S. 

CHAPTER  X. 

PATHOLOGY  AND  TREATMENT  OF  HYPERSENSITIVE  DENTIN    454 
By  Hermann  Prinz,  A.M.,  M.D.,  D.D.S. 

CHAPTER  XL 

DISCOLORED  TEETH  AND  THEIR  TREATMENT 467 

By  Hermann  Prinz,  A.M.,  M.D.,  D.D.S. 

CHAPTER  XII. 

LOCAL  ANESTHESIA 498 

By  Hermann  Prinz,  A.M.,  M.D.,  D.D.S. 

CHAPTER  XIII. 
PYORRHEA  ALVEOLARIS 527 

By  Russell  W.  Bunting,  D.D.Sc. 

CHAPTER  XIV. 

E?:TRACTI0N  of  teeth,  and  other  surgical  procedures     583 
By  Chalmers  J.  Lyons,  D.D.Sc. 

CHAPTER  XV. 

PRINCIPLES  OF   ORTHODONTIA  FOR  THE  GENERAL  PRACTI- 
TIONER        653 

By  Frederick  B.  Noyes,  B.A.,  D.D.S. 

CHAPTER  XVI. 

ROENTGEN  DIAGNOSIS  IN  DENTISTRY 675 

By  Kurt  H.  Thoma,  D.M.D. 


OPERATIVE  DENTISTRY. 


CHAPTER  I. 

THE  ANATOIVIY  OF  THE  TEETH  OF  MAN. 

By  ARTHUR  HOPEWELI^SMITH,  Sc.D.,  L.R.C.P.,  M.R.C.S...  L.D.S. 

Introduction. — In  determining  the  nature  of  his  contribution  to  this 
volume  the  author  has  been  actuated  by  the  main  conception  of  pre- 
senting the  subject  with  due  regard  to  the  scope  and  character  of  the 
entire  work,  to  the  average  requirements  of  the  general  reader,  and  to 
the  limitations  of  allotted  space.  It  is  obvious  that  for  a  fuller  treat- 
ment of  the  subject  text-books  especially  dealing  with  dental  anatomy 
should  be  consulted.  Complete  discussions  of  many  of  its  branches 
are  not  germane  to  the  consideration  of  special  technical  methods  of 
immediate  interest  to  the  practitioner,  important  though  they  undoubt- 
edly are  to  the  anatomist,  pathologist  and  surgeon. 

Consequently,  this  chapter  includes  brief  descriptions  of  the  anatomy 
of  the  dental  organs  which  should  influence  daily  clinical  work,  and 
omits  much  of  purely  academic  interest.  The  facts  of  dental  histology 
and  histogenesis,  the  problems  of  dental  physiology,  and  the  resultant 
principles  of  dental  pathology  cannot  be  here  set  forth:  they  must  be 
sought  for  elsewhere. 

At  the  same  time  it  must  be  noted  that  the  earnest,  progressive 
seeker  after  truth  should  not  be  contented  with  what  is  here  so  concisely 
detailed.  Many  recent  advances  have  been  made;  but  many  debated 
and  debatable  side  issues  increasingly  demand  attention.  Many  old 
theories  have  been,  and  will  still  continue  to  be  relegated  to  the  past, 
and  the  newer  teachings  of  anatomy,  medicine,  surgery  and  pathology 
employed  and  applied  to  the  study  of  the  science  and  art  of  dental 
surgery. 

The  reader  will  be  well  advised,  therefore,  to  refer  to  modern  text- 
books, written  for  the  specific  purpose  of  providing  an  enlarged,  sure, 
clarified,  common-sense  and  scientific  basis  for  the  building  up  of  the 
2  (17) 


18  ANATOMY  OF  THE  TEETH  OF  MAN 

higher  degrees  of  knowledge  and  learmng  demanded  today  of  the 
practitioner  of  dental  surgery. 

The  use  of  a  stricter  nomenclature,  the  appeal  of  a  closer  correlation 
of  science  and  practice,  the  recognition  of  the  fact  that  the  teeth  are 
organs  of  the  body,  acting  in  siiis  modibus  as  part  controllers  of  its  well- 
being,  should  be  strongly  insisted  upon,  if  advancement  in  the  interpre- 
tation of  symptoms  and  the  diagnosis  and  treatment  of  diseases  of  the 
oral  cavity  is  desired,  as  it  is  certainly  desirable. 

In  view  of  the  foregoing  the  subject  may  be  shortly  considered 
under  the  following  headings:  (I)  Definitions.  (II)  Numeration. 
(Ill)  Morphology.  (IV)  Articulation.  (V)  Descriptive  Gross  Anatomy. 
(VI)   Relationships. 

I.     DEFINITIONS. 

A.  Collective. — ^Teeth  may  be  defined  as  hard  bodies  generally* 
found  in  the  mouth,  developed  from  the  ectoderm  and  mesoderm, 
articulated  to  the  skeleton  but  not  forming  part  of  it,  whose  major 
general  functions  are  concerned  with  the  comminution  of  food. 

B.  Individual. — The  teeth  of  man,  as  of  all  the  primates,  are  classi- 
fied as  incisors,  canines,  premolars  and  molars — so-called  from  their 
predominant  anatomic  and  physiologic  characteristics,  viz.,  those  used 
for  sectorial  purposes,  those  greatly  developed  in  the  canidce  (dogs, 
wolves,  etc.),  those  occupying  a  position  in  front  of  the  molars,  and 
those  used  after  the  fashion  of  a  flat  millstone  for  grinding  food. 

The  maxillary  incisors  in  each  half  of  each  jaw  are  two  in  number, 
in  articulation  with  the  premaxillary  bones,  that  is,  the  bones  which 
intervene  between  the  right  and  left  premaxillary  suture.  They  are 
called  the  first  and  second  incisors.  The  older  terminology — "  centrals" 
and  "laterals" — is  incorrect  for  several  reasons.  The  words  have 
no  specific  meaning.  The  so-called  "central"  is  central  to  no  anatomic 
entity.  It  occupies  a  position  either  to  the  right  or  to  the  left  of 
the  interpremaxillary  suture — ^which  corresponds  to  the  midline  of  the 
jaws  and  face — on  the  endognathion,^  and  is  probably  the  homologue 
of  the  first  incisor  of  mammalian  dentitions.  The  so-called  "lateral" 
similarly  may  assume  a  position  in  the  dental  arch  on  either  side  of  the 
labial  or  palatal  surfaces  of  the  first  incisor,  appears  to  be  the  homo- 
logue of  the  second  incisor  in  the  mammalian  dentitions,  and  is  in 
articulation  with  the  mesognathion}  The  mandibular  incisors  are  those 
teeth  attached  to  the  lower  jaw  which,  in  occlusion,  correspond  directly 
with  the  upper  teeth. 

*  Teeth  may  also  be  found  in  the  nasal  fossse.i"  sigmoid  notch  of  the  mandible, ^^ 
ovarian  teratomata,^  and  testes,^  and  attached  to  the  temporal  bone^  and  external  audi- 
tory meatus.' 


DEFINITIONS 


19 


The  maxillary  canine  is  that  tooth — no  matter  what  its  shape  or  size 
— which  is  in  articulation  with  the  maxillary  bone  (the  exognathion)  ,^ 
in  that  region  immediately  beyond  the  premaxillary  suture.  The 
mandihular  canine  is  that  tooth  in  the  mandible  which  in  occlusion 
passes  in  front  of  its  maxillary  congener.  In  the  carnivora.  for  instance, 
a  space  exists  between  the  maxillary  incisors  and  canine  for  the  purposes 
of  the  accommodation  of  this  tooth.  This  space  is  termed  a  "dias- 
tema," literally  meaning  "an  interval."  It  is  occasionally  found  in 
man  as  a  normal  interruption  to  the  regularity  of  the  dental  arch.  In 
the  typically  herbivorous  animal  there  are  no  incisors  or  canines  in 
the  upper  jaw.  The  front  portion  of  the  mandible,  however,  carries 
four  teeth  on  each  side  of  the  suture  at  the  symphysis  menti.  Of  these 
the  fourth  or  outermost;  is  small  and  incisiform  in  shape.  It  is,  never- 
theless, a  canine,  its  period  of  development  and  eruption  being  con- 
siderably later  than  that  of  the  three  incisors,  it  being  impossible  for 
mammals  (except  the  polyprotodont  marsupials)  normally  to  possess 
more  than  three  incisors  on  each  side  of  the  middle  line  of  the  face. 


Fig.  1. — Palatal  aspect  of  maxillae  of  child  aged  five  and  a  half  years,  showing  various 
sutures.  1,  interpremaxillary  suture;  2,  endognathion;  3,  mesognathion;  4,  exognathion; 
5,  premaxillary  suture;  6,  median  maxillary  suture. 

The  premolars  are  two  in  number  on  either  side  of  each  jaw.  They 
are  so-called  because  they  are  situated  immediately  in  front  of  the 
permanent  molars,  and  in  eruption  have  displaced  two  predecessors, 
viz.,  the  deciduous  molars.  They  are  termed  the  first  and  second 
premolars,  though  they  probably  represent  the  third  and  fourth 
premolars  of  the  typical  mammalian  dentition.  These  teeth  have 
been  generally  known  as  "bicuspids,"  But  recent  trend  of  thought, 
determined  by  a  careful  examination  of  many  specimens  in  the  mouth 
of  man,  and  by  a  study  of  the  anatomic  relationships  of  man  to  the 
primates,  show  that  the  term  is  a  misnomer,  for  the  following  reasons: 
the  crowns  of  many  maxillary  canines  possess  a  prominent  cusp  on 
their  lingual  aspects.  Incisors  frequently  have  a  well-defined  prominent 
lingual  tubercle.    In  both  instances  this  is  an  elevation  of  the  internal 


20  ANATOMY  OF  THE  TEETH  OF  MAN 

part  of  the  cingulum.  They  are,  therefore,  bicuspid  ate.  Further, 
the  first  mandibular  premolar  has  often  the  lingual  cusp  so  ill-defined 
and  underdeveloped  that  it  appears  merely  as  a  raised  tubercle  and 
cannot  properly  be  called  a  cusp.  The  second  mandibular  premolar 
is  frequently  tricuspidate,  and  may  on  occasion  be  multi-tuberculate. 
These  objections  cannot  be  raised,  however,  if  the  teeth  are  considered 
as  the  homologues  of  the  mammalian  dentition. 

The  'permanent  molars  are  three  in  number  in  each  half  of  each  jaw, 
erupt  in  typical  diphyodonts  behind  the  milk  molars,  and  have  no 
predecessors.  The  existence  of  a  fourth  molar  is  impossible;  no 
typical  mammal  possesses  such  a  tooth.  The  "fourth  molar"  of  some 
authors^  is  a  more  or  less  molariform  supernumerary  tooth.  The 
deciduous  molars  are  those  teeth  which  have  been  displaced  during  the 
growth  and  eruption  of  the  subjacent  premolars.  They  are  correctly 
termed  the  first,  second  and  third  molars  in  the  first  instance  and  the 
first  and  second  molars  in  the  second  instance. 

n.     NUMERATION. 

There  is  a  marked  reduction  in  the  number  of  the  teeth  of  man 
compared  with  that  of  the  typical  mammalian  dentition,  as  seen,  for 
example,  in  the  mole,  young  horse  and  pig.  Here  the  full  dental 
formula  gives  on  one  side  of  either  jaw  three  incisors,  a  canine,  four 
premolars  and  three  molars.  Adopting  the  usual  symbols  this  may  be 
represented  graphically: 

I  I,  C  1,  Pm  f,  M,  f  =  22  or  X  2  =  44  in  the  entire  oral  cavity. 
The  normal  human  permanent  dentition  is  denominationally  and 
numerically  expressed  thus: 

1  f ,  C  I,  Pm  f ,  M  f  =  16,  or  X  2  =  32; 
and  the  deciduous  series: 

i  f ,  c  1,  m  f  =  10,  or  X  2  =  20. 


f ,  c  1,  m  f  =  10,  or  X  2  = 


Reasons  for  the  Departure  from  the  Typical  Mammalian  Formula. — 

Examination  of  the  preceding  formulae  shows  that  man  has  twelve 
permanent  teeth  less  than  the  typical  number — four  incisors  and 
eight  premolars.  The  factors  in  the  production  of  this  condition  are 
probably^''  as  follows: 

1.  Incomplete  evolution  of  certain  teeth  which  are  practically 
functionless,  such  as  the  third  molars,  following  the  rule  of  degeneracy 
of  other  organs  of  the  body,  as  exemplified,  for  instance,  in  the  vermi- 
form appendix  and  the  plica  semilunaris,  which  are  important  in  the 
rabbit,  and  as  the  third  eyelid  of  birds  and  Hzards,  etc. 


MORPHOLOGY 


21 


2.  The  progressive  enlargement  of  the  most  actively  functional 
organs,  as  typified  in  the  comparatively  great  size  of  the  fourth  pre- 
molar in  the  felidce,  the  dynamic  effects  of  unusually  great  muscular 
action  in  the  zygomatic  region;  and 


Fig.  2. — Left  side  of  jaws  of  man  with  permanent  teeth  in  situ. 


3.  The  shortening  of  the  length  of  the  entire  jaw  of  man  in  com- 
parison with  that  of  many  of  the  mammalian  series  of  animals.  This 
reduction  in  the  antero-posterior  direction  results  in  the  crowding  out 
of  teeth  which,  as  organs  for  the  comminution  of  food,  can  best  be 
spared.  While  the  general  size  and  shape  of  the  teeth  of  modern  man 
have  undergone  little  change  during  his  evolution,  his  jaws  have. 
There  is  less  room  in  his  mouth  for  the  attachment  of  his  teeth  than 
there  was  in  the  more  spacious  oral  cavity  of  his  prehistoric  simian 
ancestor. 

III.     MORPHOLOGY. 

In  attempting  to  affix  the  conception  of  a  geometrical  basis  to  any 
consideration  of  the  shapes  of  the  organs  of  man,  it  must  be  remembered 
that,  in  spite  of  the  necessity,  when  describing  such  organs,  of  adopting 
mathematical  ideals,  it  was  probably  never  the  intention  on  the  part 
of  nature  to  construct  an  architectural  type  which  would  be  completely 
subservient  to  geometrical  pattern  or  design.    If  it  were  so,  then  of 


22  ANATOMY  OF  THE  TEETH  OF  MAN 

all  the  organs  of  the  body  his  teeth  lend  themselves  most  to  this  treat- 
ment; more  so  than  his  palate  or  his  dental  arches. 

It  is  usual,  however,  to  describe  the  shapes  of  the  teeth  as  being 
dependent,  especially  as  far  as  the  roots  are  concerned,  on  the  mor- 
phological variations  of  that  geometrical  figure  known  as  a  cone.  The 
roots  of  human  teeth  are  conical,  thoroughly  adapted  to  their  unique 
articulation  with  the  alveolar  processes  of  the  jaws.  Roots  may  be 
cylindrical,  flattened  laterally,  straight,  curved  or  twisted. 

With  regard  to  the  evolution  of  the  pattern  of  their  crowns  three 
schools  of  thought  may  be  cited  as  holding  concurrent  views,  varying 
chiefly  by  reason  of  the  differences  of  the  viewpoint  of  their  genesis 
and  development. 

Of  these  the  simpler  is  the  theory  of  (A)  the  fusionists,^*^  ^^  ^^  ^'^ 
who  hold  that  in  consequence  of  the  decrease  in  shape  and  size  of  the 
jaws,  haplodont  (cone-shaped)  teeth  may  exist  per  se,  or,  becoming 
fused,  may  produce  a  molariform  pattern.  (B)  The  trituberculists^^  ^^ 
have  advanced  the  theory  that,  during  the  course  of  evolution  from 
the  primitive  type,  haplodont  teeth  may  develop  on  the  chief  cone, 
subsidiary  cusps  in  anterior,  posterior  and  lateral  directions.  A 
further  extension  of  the  tubercular  theory  may  be  called  (C)  the  multi- 
tubercular  theory,^^ 

A  discussion  as  to  the  merits  of,  and  objections  to,  these  views  is 
not  relevant  to  this  article.  It  may,  however,  suffice  to  say  that  prob- 
ably the  crowns  of  the  human  incisors  are  merely  flattened  cones, 
that  the  canine  largely  retains  its  primitive  shape,  while  the  molariform 
crowns  of  the  three  posterior  teeth  are  chiefly  due  to  a  longitudinal 
fusion  of  original  haplodont  cones.  In  the  case  of  the  premolars  it  is 
believed  that  the  internal  cusp  is  a  modification  of  the  cingulum,  in 
which  an  elevation  of  its  inner  part  produces  a  tubercle  of  varying 
proportions. 

The  reasons  for  the  diversities  in  shape  of  the  crowns  of  teeth  may 
be  ascribed  to  .  the  operations  of  the  laws  of  adaptive  modification, 
which  demonstrate  that,  following  the  deterioration  and  suppression 
of  disused  and  unwanted  organs  and  the  more  complete  morphological 
development  of  really  necessary  and  much  used  organs,  certain  slow, 
progressive  modifications  from  few  and  simple  forms  occur.  Of  all 
the  teeth  the  third  maxillary  molar  and  probably  the  second  maxillary 
incisor  are  the  least  used  as  mechanical  agents.  These  teeth,  par- 
ticularly the  former,  have  a  tendency  to  undergo  suppression  and  to 
evince  in  their  coronal  patterns  traces  of  retrogressive  and  unstable 
characteristics.  In  short:  the  law  which  governs  the  fixed  mor- 
phological features  of  the  teeth  is  founded  upon  the  requirements  of 
nature  in  connection  with  the  provision  of  an  organ  or  of  several 


ARTICULATION  23 

organs  most  suitably  designed  and  constructed  to  accomplish  the  very 
definite  purpose  for  which  they  were  intended. 

Succession. — Man,  like  most  animals,  is  a  diphyodont  animal, 
i.  e.,  he  possesses  two  sets  of  teeth,  the  deciduous  or  milk,  and  the 
permanent  series.  A  third  set,  occasionally  spoken  of  by  the  unlearned, 
cannot  exist.  Vestigial  dental  remains  are  exceptionally  found  in  the 
human  jaws  and  are  believed  by  some  evolutionists^^  to  point  to  a 
reversion  to  a  reptilian  dentition  in  which  a  polyphyodont  condition 
obtains. 

IV.     ARTICULATION. 

Teeth  are  attached  to  the  jaws  by  means  of  a  unique  joint  or  articu- 
lation, termed  "gomphosis,"  exactly  imitating  the  arrangement  of  a 
nail  or  peg  when  received  into  a  hole  or  mortise  in  a  piece  of  wood; 
hence  the  term.  Gomphosis  is  a  variety  of  synarthrosis^^  ^* — a  fixed, 
immovable  joint,  as  exemplified  in  the  methods  of  union  of  the  bones 
of  the  cranium.  It  is  limited  to  the  teeth.  The  socket  containing 
the  cone-shaped  root  is  termed  the  alveolus,  and  those  portions  of  the 
jaws  which  support  the  sockets  are  called  the  alveolar  processes.  The 
teeth  are  immovably  held  in  position  through  the  cementum  on  the 
inner  side  by  a  strong  fibrous  attachment  to  the  lamina  dura — a  thin 
sheet  of  compact  bone  surrounding  their  alveolar  sockets  on  the  outer 
side — through  the  intervention  of  a  dense,  firm  layer  of  connective 
tissue  called  the  alveolo-dental  periosteum. 

Just  as  it  may  be  affirmed  without  fear  of  refutation  that  the  masti- 
catory organs  of  modern  men  are  degenerate  and  unfitted  to  perform 
properly  their  functions  throughout  the  lifetime  of  the  individual, 
so  may  it  be  stated  that  their  sockets  are  equally  unsuited  to  their 
desired  requirements.  It  is  the  rule  that  they  should  atrophy  and 
disappear  with  the  incidence  of  age. 

The  terminal  margins  of  the  sockets  of  the  teeth  of  man  are  of  a 
degenerate  character  for  the  following  reasons:^'' 

1.  Absence  of  muscular  attachment.  No  muscles  or  parts  of  muscles 
arise  from  or  are  inserted  into  the  alveolar  processes  of  the  jaws,  except 
a  few  stray  fibers  of  the  buccinator  in  the  neighborhood  of  the  maxillary 
molars.  The  fundamental  function  of  bone  is  therefore  entirely  absent 
in  this  situation. 

2.  The  unique  character  of  the  structure  of  the  bone  does  not 
completely  conform  either  to  the  compact  or  cancellous  varieties. 

3.  Inadequacy  of  the  blood  supply  tends  to  produce  anemia  of  the 
parts,  and  this,  when  long  continued,  is  likely  to  lead  to  atrophy. 

4.  Physiologic  resistance  to  disease  and  nutritional  equilibrium  are 


24  ANATOMY  OF  THE  TEETH  OF  MAN 

easily  and  readily  lowered  and  disturbed  by  the  extreme  tenuity  and 
other  histologic  features  of  the  external  and  internal  alveolar  plates. 

5.  There  is  a  modification  of  the  usual  function  of  bones,  which,  in 
this  particular  instance,  is  only  required  to  support  and  afford  attach- 
ment to  the  roots  of  teeth. 

V.     DESCRIPTIVE  GROSS  ANATOMY. 

A.  The  Permanent  Series. — 1.  The  Maxillary  Teeth.^ — ^The  First 
Incisor. — In  articulation  with  the  endognathion  and  placed  on  either 
side  of  the  intermaxillary  suture,  which  corresponds  to  the  midline  of 
the  jaw  and  face,  this  tooth  with  its  congener  of  the  opposite  side  forms 
one  of  the  most  striking  objects  of  the  dental  series.  The  graceful 
size  and  shape  of  its  crown  make  it  of  great  importance  in  its  relation- 
ship to  the  other  teeth  and  to  the  aesthetic  bearing  it  has  on  the  features 
generally. 

It  is  usually  placed  in  close  proxinaity  to  its  fellow  in  the  other  maxilla, 
but  frequently  in  early  life  a  space  exists  between  the  two  first  incisors. 
This  is  due  to  an  excessive  development  and  consequent  enlargement' 
of  the  bone  of  the  alveolar  sockets  of  the  teeth,  particularly  at  the  side 
nearest  the  suture,  a  hypertrophy  probably  induced  and  continued 
by  the  presence  and  action  of  a  large  frenum  labii,  w^hich  is  inserted 
into  the  soft  tissues  of  the  labial  aspect  of  the  alveolar  process. 

The  crown  has  four  surfaces,  six  borders,  and  two  angles,  named 
respectively  (1)  labial,  or  vestibular,  or  external,  or  anterior,  (2) 
lingual,  caval,  internal,  or  posterior,  (3)  mesiaP  and  (4)  distal;  incisive 
edge  or  inferior  border,  gingival  edge  or  superior  border,  and  mesio- 
anterior  and  mesio-posterior  and  disto-anterior  and  disto-posterior 
borders.    The  angles  are  mesial  and  distal. 

Surfaces.- — ^The  labial  is  the  largest  of  all  the  surfaces.  It  is  markedly 
convex  from  above  downward  and  from  side  to  side.  Its  upper  border 
is  narrow  and  rounder  than  the  lower,  thus  making  it  triangular  m 
outline.  Smooth  usually,  it  may  be  traversed  by  numerous  horizontal 
ridges  or  pits  or  depressions,  and  is  frequently  discolored  and  pig- 

1  The  terms  "mesial"  and  "distal,"  common  in  clinical  parlance,  are  not  strictly 
anatomically  correct.  It  is  the  rule  in  general  anatomy  to  designate  that  part  or  surface 
of  a  long  bone  nearest  to  the  larger  joint  as  "proximal,"  that  away  from  the  large  joint 
"distal."  Thus,  in  the  femur  the  part  of  the  bone  at  the  hip  is  called  the  "proximal 
extremity,"  that  at  the  knee  the  "distal  extremity."  So  it  should  be  with  the  teeth. 
Owing  to  the  shape  of  the  dental  arches  the  mesial  surfaces  of  the  incisors  face  in  exactly 
the  same  direction — toward  the  midline — as  do  the  lingual  surfaces  of  the  premolars 
and  molars,  their  distal  surfaces  as  the  buccal  surfaces  of  these  teeth.  It  is  more  in 
accordance  with  anatomic  usage  to  consider  the  so-called  "mesial  surface,"  i.  e.,  the 
part  further  away  from  the  joint,  viz.,  the  temporo-mandibular  articulation — as  the 
"distal  surface,"  and  the  so-called  "distal"  as  the  "proximal  surface,"  For  the  conven- 
ience of  the  reader,  however,  the  usual  clinical  terms  will  be  here  adopted. 


DESCRIPTIVE  GROSS  ANATOMY  25 

merited  as  the  result  of  either  congenital  or  acquired  conditions.  Oc- 
casionally a  median  vertical  ridge  may  divide  the  surface  into  two 
unequal  parts. 

The  lingual  surface  is  remarkable  for  its  pronounced  double  con- 
cavities. Smaller  than  the  above,  with  thickened  and  elevated  bound- 
aries, it  is  triangular  in  shape,  the  base  being  at  the  incisive  edge.  A 
diminutive  cusp  or  tubercle  frequently  appears  at  the  gingival  margin. 
It  represents  an  elevation  of  the  cingulum. 

On  the  mesial  aspect  the  crown  is  slightly  convex  in  both  vertical 
and  lateral  directions.  It  is  enclosed  by  the  rounded  mesio-anterior 
and  mesio-posterior  borders,  which  in  many  instances  are  scarcely 
elevated  from  the  general  level  of  the  surface  and  therefore  indistin- 
guishable to  any  extent.  The  upper  borders  follow  more  or  less  closely 
the  outline  of  the  surface  itself.  Of  its  two  parts,  that  directed  to  the 
external  side  is  shorter  than  that  directed  to  the  internal  side. 

The  distal  surface  is  more  convex  than  the  former,  a  little  larger 
generally,  as  a  consequence  of  the  superior  border  not  curving  down- 
ward so  markedly.  The  whole  of  this  doubly-convex  surface  passes 
into  the  disto-anterior  and  disto-posterior  borders  without  any  per- 
ceptible interruption. 

The  incisive  edge  is  blunt,  slightly  convex  and  slightly  thicker  toward 
the  mesial  side.    Three  tubercles  may  be  present  here  at  birth. 

The  gingival  edge  varies  over  the  different  aspects  of  the  crown.  On 
the  labial  side  it  forms  part  of  the  circumference  of  a  circle.  Lingually 
it  is  considerably  flattened — nearly  in  a  straight  line,  mesially  it  dips 
down  some  considerable  distance  near  the  middle  portion  toward  the 
mesial  angle,  and  distally  it  is  less  curved  than  in  the  last-named 
situation. 

The  mesio-anterior,  mesio-posterior,  disto-anterior  and  disto-posterior 
borders  are  all  rounded  and  smooth,  and  in  the  majority  of  instances 
are  not  elevated  over  and  above  the  surfaces  which  they  enclose. 

Of  the  angles,  the  mesial  is  nearly  a  right  angle,  the  distal  is  obtuse. 

The  neck  of  the  tooth  is  clearly  defined,  on  account  of  the  prominence 
of  the  free  edge  of  enamel  and  its  relationship  with  the  cementum 
above.  It  does  not  lie  in  the  same  horizontal  plane,  but  as  it  passes 
around  the  tooth  it  is  elevated  or  depressed,  according  to  the  situation. 
Thus  labially  and  lingually  it  is  very  much  raised,  distally  and  mesially 
it  is  considerably  depressed  toward  the  incisive  border  of  the  crown. 

The  root  is  normally  almost  a  cylindrical  cone  and  the  alveolar 
socket  also  necessarily  cylindrical.  Usually  straight,  it  may  be  de- 
flected slightly  toward  the  middle  line.  Flattened  laterally,  it  becomes 
at  times  somewhat  triangular  in  outline.  It  may  rarely  be  bifurcated, 
the  second  root  being  placed  on  the  lingual  side. 


26 


ANATOMY  OF  THE  TEETH  OF  MAN 


The  pidiJ  cavity  generally  follows  in  shape  the  outline  of  the  tooth 
itself,  viz.,  two  cones  of  dissimilar  size  placed  together  at  their  bases. 
Of  these  the  radicular  portion  is  considerably  the  larger.  Viewed  in 
a  mesio-distal  direction  the  lower  part  of  the  pulp  cavity  is  the  broadest, 
and  is  divided  into  three  cornua,  of  which  the  central — the  smallest — 
disappears  at  about  the  fifteenth  year.  The  root  canal  is  tube-like, 
narrow  and  straight. 


A  B  c  D 

Fig.  3. — Maxillary  first  incisor.     A,  labial  surface;  B,  lingual  surface;  C,  mesial  surface; 

D,  mesio-distal  section. 


The  calcification  of  this  tooth  begins  during  the  first  year  after 
birth  ;^  its  apical  foramen  forms  about  the  tenth  to  eleventh  years,^ 
and  it  is  erupted  at  the  seventh  year  and  ninth  month.^^ 

Length,  approximately  25  mm.;^^  width,  9  mm. 

Identification,  from  a  number  of  specimens  isolated  from  the  mouth, 
can  be  effected  by  placing  the  tooth  in  a  horizontal  position,  with 
convex  coronal  surface  upward  and  root  away  from  the  observer,  and 
noting  the  more  acute  angle  of  the  incisive  edge.  This  points  to  the 
side  to  which  the  tooth  belongs. 

Methods  of  normal  occlusion.  This  tooth  completely  overlaps  the 
upper  sixth  of  the  labial  surfaces  of  the  first  and  second  mandibular 
incisors. 

The  Second  Incisor. — ^This  tooth,  the  second  from  the  midline  of 
the  face,  in  articulation  with  the  mesognathio7i,  is  situated  on  the 
distal  side  of  the  first  incisor.  It  is  frequently  suppressed.  It  simu- 
lates, though  on  a  smaller  scale,  the  first  incisor  in  its  main  archi- 
tectural features. 

Similarly  to  the  first  incisor  the  croum  has  four  surfaces,  six  borders 
and  two  angles. 

Of  all  the  surfaces  the  labial  is  the  largest,  and  differs  from  that  of 
the  other  incisor  in  the  more  pronounced  diminution  in  size  as  it 
approaches  the  gingival  margin.  Hence  the  whole  aspect  is  very 
triangular  in  outline.    Markedly  convex  in  both  directions  it  assumes 


DESCRIPTIVE  GROSS  ANATOMY  27 

a  transitional  type  of  shape  between  the  flatter  first  incisor  and  the 
more  conical  canine.  Of  the  two  convexities,  that  from  side  to  side  is 
the  more  appreciable.  Its  superficial  markings  are  not  so  well  defined 
as  in  the  other  incisor. 

Lingually  the  appearance  of  the  crown  follows  that  of  the  first 
incisor,  save  that  it  is  smaller  in  every  dimension.  Its  concavities 
are  greater.  A  slight  vertical  ridge  may  be  formed  at  times  on  this 
surface,  separating  two  deep  concavities.  The  internal  cingulum  may 
be  modified  into  a  cusp. 

The  mesial  surface  is  slightly  larger  than  the  distal.  It  is  flattened 
from  side  to  side  and  slightly  convex  from  above  downward.  It  passes 
imperceptibly  into  the  mesio-anterior  and  mesio-posterior  borders. 

The  distal  surface  is  much  more  convex  in  both  directions  than  the 
former.  It  is  smaller  in  area,  being  vertically  shorter  and  encroached 
upon  by  the  disto-anterior  and  dis to-posterior  borders. 

The  incisive  edge  is  broad  and  round  and  does  not  present  the  blade- 
like appearance  as  in  the  first  incisor.  It  is  short  in  a  mesio-distal 
direction,  largely  through  the  shape  of  the  distal  angle.  Three  tubercles 
may  frequently  be  seen. 

The  gingival  edge  is  very  narrow  compared  with  the  former,  par- 
ticularly on  its  labial  aspect.  It  forms  the  arc  of  a  much  smaller  circle 
than  in  the  first  incisor.  The  cervical  edge  of  enamel  in  this  locality  is 
not  very  pronounced. 

Of  the  borders,  all  are  considerably  rounded,  flat  and  broad,  so  much 
so  that  it  is  often  impossible  to  define  the  actual  limits  of  surface  and 
border.  This  condition  is  more  obvious  on  the  distal  than  on  the  mesial 
side. 

The  angles  are  obtuse,  particularly  the  distal. 

The  neck  copies  that  of  the  first  incisor,  but  the  undulations  are  less 
marked  and  the  constriction  less  severe. 

The  Root. — Cone-shaped  and  flattened  laterally  the  labial  and 
lingual  sides  of  the  root  are  broader  than  the  other  two  surfaces.  Of 
these  two  the  lingual  is  the  narrower.  The  root  is  generally  straight 
but  may  be  deflected  toward  the  distal  side,  and  may  be  bifurcated. 
When  in  situ  it  has  a  tendency  to  be  directed  toward  the  midline  of 
the  palate.  Hence  it  follows  that  a  dento-alveolar  abscess  resulting 
from  a  septic  pulp  points  over  the  palate  in  the  cavum  oris. 

The  Pulp  Cavity. — Compared  with  the  general  size  of  the  tooth 
itself  the  pulp  cavity  is  the  largest  of  all;  compared  with  that  of  the 
first  incisor  it  is  a  little  smaller  in  every  dimension.  Two  cornua 
exist,  as  in  the  last-named  tooth;  the  one  on  the  mesial  side  being 
frequently  the  largest.  The  root  canal  is  a  narrow  tube;  an  accessory 
root  canal  is  a  fairly  common  abnormality. 


28 


ANATOMY  OF  THE  TEETH  OF  MAN 


Calcification  begins  during  the  first  twelve  months,  finishes  with 
the  formation  of  the  apical  foramen  at  the  tenth  to  the  eleventh  year, 
and  the  tooth  is  erupted  at  about  the  third  year  and  ninth  month. 

It  measures  approximately  23  by  6.5  mm.  in  greatest  length  and 
diameter. 

Identify  similarly  to  the  first  incisor. 

Occlusion. — ^The  lingual  surface  occludes  with  the  upper  sixth  of 
half  the  labial  surfaces  of  the  mandibular  second  incisor  and  canine. 


A  B 

Fig.   4. — Maxillary  second  incisor.     A,  labial  surface;   B,  lingual   surface;   C,   mesial 

surface;  D,  distal  surface. 


The  Canine. — This  important  tooth  is  the  third  from  the  midline 
of  the  face,  its  socket  occupying  the  alveolar  process  of  the  exog- 
nathion.  Situated  at  the  angle  of  the  alveolar  processes  of  the  upper 
jaw,  in  possession  of  a  large  root,  and  producing  the  canine  eminence 
behind  the  canine  fossa  on  the  facial  surface  of  the  maxillary  bonC; 
the  tooth  is  remarkable  for  its  size,  strength  and  general  appearance. 
It  is  by  far  the  largest  tooth  in  the  anterior  part  of  the  dental  series. 

The  crown,  a  somewhat  flattened  cone,  has  four  surfaces,  six  borders 
and  two  angles. 

The  lahial  surface,  the  largest  of  the  four,  is  slightly  convex  from 
above  downward  and  more  so  from  side  to  side.  It  forms  the  rough 
outline  of  a  pentagon,  having  one  side  above  at  the  gingival  margin^ 
a  second  and  third  below  at  the  cutting  edge,  and  in  front  and  behind 
a  fourth  and  a  fifth,  joining  the  extremities  of  the  others.  Frequently 
this  surface  is  divided  by  a  median  ridge  into  two  unequal  parts,  of 
which  the  anterior  is  the  smaller. 

On  the  lingual  surface,  which  presents  the  outline  of  a  five-sided 
figure,  are  two  deep  depressions  separated  by  a  vertical  ridge,  which 
terminates  below  at  the  extremity  of  the  cusp,  and  above  very  often 
in  an  accessory  cusp  of  varying  size,  which,  like  that  of  the  first  incisor, 
represents  an  elevation  of  the  internal  cingulum.  Of  these  concavities 
that  on  the  distal  side  is  the  larger. 

The  mesial  surface  is  flattened  and  smaller  in  extent  than  that  of 


DESCRIPTIVE  GROSS  ANATOMY 


29 


the  opposite  side  through  the  undue  encroachment  of  the  root  at  the 
cervical  margin.  It  is  flat,  triangular,  with  an  indented  base  and 
broad  apex,  and  is  generally  on  the  same  level  as  that  of  the  root. 
Hence  the  upper  edge  of  enamel  is  very  slightly  elevated. 

Distally  a  unique  characteristic  of  the  canine  appears.  This  is  a 
prominence,  not  amounting  to  a  definite  tubercle  or  cusp,  large  in 
extent,  and  situated  at  the  lower  part  of  the  surface  at  the  junction  of 
what  would  represent  in  the  incisors  the  disto-anterior  and  disto-pos- 
terior  borders.  The  upper  border  of  this  surface  is  almost  on  a  hori- 
zontal plane.  The  canine  does  not  usually  possess  any  well-defined 
borders.    All  its  surfaces  are  more  or  less  rounded  and  smooth. 

Of  the  angles  the  distal  is  the  more  obtuse.  At  times  they  may  be 
raised  into  prominences  w^hich  give  the  appearance  of  a  tricuspidate 
tooth. 

The  neck  forms  a  gentle  undulating  line  which,  labially,  is  part  of  a 
flattened  arc  of  a  circle,  and  extends  downward  slightly  on  the  mesial 
and  distal  aspects,  ending  lingually  in  a  nearly  horizontal  direction. 

The  root  is  an  extremely  elongated,  flattened  cone,  of  which  the 
mesial  aspect  is  the  broader  and  the  lingual  the  narrower  in  diameter. 
Two  vertical  grooves  can  usually  be  noted,  that  on  the  mesial  side 
being  the  deeper.  The  root,  when  unduly  lengthy,  may  communicate 
with  the  maxillary  sinus. 

The  2J^<?2^  cavity  extends  into  the  coronal  region  in  the  form  of  one 
cornu.  In  the  crown  it  is  almost  triangular  in  outline;  at  the  neck 
nearly  cylindrical ;  at  the  junction  of  the  upper  two-thirds  and  the  lower 
third  compressed  from  side  to  side;  and  at  the  apex  cylindrical. 


A  B  CD 

Fig.   5. — Maxillary  canine.     A,  labial  surface;  B,  lingual  surface;  C,   mesial  surface; 

D,  labio-lingual  section. 


Calcification  begins  during  the  third  year  and  is  completed  from  the 
twelfth  to  the  thirteenth.    Eruption  occurs  at  about  the  tenth  year  and 


30  ANATOMY  OF  THE  TEETH  OF  MAN 

sixth  month,  thus  precedmg  the  complete  formation  of  the  apical 
foramen. 

Average  length  and  width  27  mm.  and  8  mm. 

Identification  can  be  effected  by  the  same  means  as  for  the  incisors. 
The  disto-coronal  prominence  points  to  the  side  opposite  to  that  to 
which  the  tooth  belongs. 

Occlusion. — By  its  lingual  surface  it  occludes  with  the  labial  aspect 
of  the  corresponding  tooth  in  the  lower  jaw  and  the  anterior  part  of 
the  upper  portion  of  the  labial  surface  of  the  mandibular  first  premolar. 

The  First  Premolar. — ^Fourth  from  the  front  this  tooth  in  man 
probably  represents  the  third  premolar  of  the  typical  mammalian 
dentition,  thus  following  the  general  rule  that  when  premolars  are 
absent  from  the  dentition  of  an  animal  those  nearest  the  canine  are  the 
most  likely  to  be  suppressed.  The  definition  of  the  premolars  already 
given  suffices  to  indicate  that  these  teeth  are  situated  in  the  jaw  in 
front  of  the  permanent  molars  and  that  they  have  displaced  deciduous 
molariform  predecessors.  It  should  further  be  noted,  as  will  presently 
appear,  that  a  second  mandibular  premolar  may  present  many  cusps 
or  tubercles,  and  cannot,  therefore,  be  strictly  called  a  "bicuspid"  at 
all. 

This  tooth  may  be  in  relation  with  the  antrum  of  Highmore  in  its 
facial  portion. 

Totally  unlike  the  preceding,  the  first  premolar  possesses  a  crown 
with  five  surfaces,  a  neck,  and  a  root  or  roots. 

The  crown  presents  for  examination  a  labial,  lingual,  mesial,  distal 
and  a  morsal  or  occluding  surface. 

The  shape  of  the  labial  surface  in  typical  examples  combines  the 
mathematical  outlines  of  the  pointed  cutting  edge  of  the  canine  and 
the  constricted  neck  of  the  second  incisor.  It  is  slightly  convex  from 
above  downward  and  more  so  from  side  to  side.  The  median  ridge  and 
lateral  vertical  grooves  commonly  seen  on  the  corresponding  surface 
of  the  canine  are  often  here  entirely  absent,  the  whole  area  being  quite 
smooth.  The  general  outline  resembles  somewhat  that  of  a  diamond, 
with  the  upper  angle  flattened. 

A  great  resemblance  exists  between  the  lingual  surface  and  the 
former,  the  main  difference  being  that  its  superficies  is  less  in  all  direc- 
tions, and  the  upper  angle  of  the  diamond  is  flatter.  No  grooves  or 
ridges  normally  exist. 

The  quadrilateral  face  of  the  mesial  siuface  is  notable  for  the  thick- 
ening of  its  lower  border,  which  in  some  cases  may  amount  almost  to  a 
unique  elevation  of  the  cingulum.  It  is  slightly  concave  vertically  and 
in  a  labio-lingual  direction. 

The  distal  surface  is  similar  to  the  above,  but  instead  of  being  slightly 


DESCRIPTIVE  GROSS  ANATOMY  31 

concave  it  is  somewhat  convex.  It  is  rather  larger  in  area,  with  rounded 
borders. 

The  morsal  or  occluding  surface  is  roughly  trapezoidal  in  outline. 
Its  mesio-distal  diameter  is  considerably  less  than  its  other  diameters. 
The  labial  border  of  the  figure  is  the  largest  of  the  four,  the  next 
largest  being  the  posterior  or  distal  border.  The  surface  is  not  plain, 
but  is  divided  topographically  into  elevations  or  cusps,  depressions  or 
sulci  or  fissures.  Almost  in  the  center  of  this  surface  extends  a  short, 
deep  sulcus  which  runs  forward  nearly  parallel  with  the  intermaxillary 
suture.  At  its  anterior  (mesial)  extremity  it  runs  at  an  angle  outward 
and  forward ;  at  its  posterior  (distal)  end  it  runs  at  a  more  obtuse  angle 
outward  and  backward.  Frequently  in  the  latter  situation  it  bifur- 
cates. The  chief  cusp  is  on  the  external  part  of  this  surface.  It  is 
very  large  and  round  on  its  morsal  aspect,  sharp  and  pyramidal  on  its 
labial  aspect.  It  is  separated  by  the  antero-posterior  sulcus  from  the 
smaller,  blunter  internal  or  lingual  cusp.  In  well-formed  specimens 
the  whole  of  this  cusp  is  round,  but  in  many  examples  the  outermost 
cusp  is  apparently  formed  by  the  union  of  four  ridges  of  enamel,  one 
passing  forward  to  the  outer  mesial  angle,  another  backward  to  the 
outer  distal  angle,  another  toward  the  center  of  the  surface,  and  another 
uniting  with  a  possibly  existing  vertical  ridge  on  the  labial  or  buccal 
surface  of  the  crown.  If  the  sulcus  bifurcates  at  one  or  either  extremity 
one  or  two  additional  eminences  of  enamel  are  produced.  It  is  there- 
fore possible  on  the  lingual  side  of  this  surface  for  two  additional  cusps 
to  be  observed. 

The  neck  is  placed  in  a  nearly  horizontal  plane,  slight  undulations 
occurring  on  all  four  faces  of  the  root. 

The  root  or  roots.  In  about  60  per  cent,  of  cases  the  first  premolar 
is  birooted.  In  single-rooted  specimens,  both  very  flattened  surfaces 
usually  present  a  more  or  less  deep  groove,  that  on  the  mesial  being 
greater  than  that  on  the  other  side.  If  these  grooves  attain  any  great 
depth  during  development  the  tooth  then  becomes  bifid  and  birooted, 
each  portion  containing  a  typically-shaped  pulp  canal.  These  roots 
may  be  quite  distinct  throughout  their  whole  extent,  but  generally 
they  are  united  through  two-thirds  of  their  length.  Occasionally 
one  lingual  and  two  buccal  roots  are  found.  This  is  probably  an 
expression  of  atavism.  The  apical  region  is  frequently  divergent  and 
deflected  backward. 

In  the  pulp  cavity,  which  closely  conforms  to  the  shape  of  the  crown, 
the  cornu  found  on  the  buccal  side  is  the  more  extensive,  penetrating 
far  into  the  cusp;  if  two  pulp  canals  exist  the  division  from  the  common 
pulp  chamber  in  the  crown  occm-s  at  the  cervical  region.  The  greatest 
diameter  of  the  pulp  cavity  is  in  the  labio-lingual  direction. 


32 


ANATOMY  OF  THE  TEETH  OF  MAN 


Calcification  commences  at  about  the  fourth  year,  and  the  apical 
foramen  becomes  formed  between  the  eleventh  and  twelfth.  Eruption 
takes  place  at  about  the  ninth  year,  or  the  ninth  year  and  sixth  month. 

Length,  20  mm.;  ividth,  6.5  mm. 

Identification. — ^The  side  of  the  mouth  to  which  the  tooth  belongs  is 
indicated  by  the  deeper  of  the  two  grooves  of  the  root,  when  the  tooth 
is  placed  with  its  crowai  toward  the  observer  and  its  larger  external 
cusp  also  in  the  same  direction. 

Occlusion  occurs  by  means  of  the  lingual  cusps  of  the  crown  coming 
into  contact  with  the  distal  ridges  of  the  cusp  of  the  mandibular  first 
premolar,  and  the  mesial  ridges  of  both  cusps  of  the  second  premolar. 


A 


B 


C  D 

Fig.    6. — Maxillary  first   premolar.     A,   buccal  surface;  B,   distal  surface;    C, 
surface;  D,  bucco-lingual  section. 


mesial 


The  Second  Premolar. — ^The  homologue  of  the  fourth  premolar 
of  the  tj^ical  mammalian  dentition,  this  tooth  is  the  fifth  from  the 
midline  of  the  jaws  and  face.  It  is  more  constant  than  the  preced- 
ing in  its  morphologic  characteristics,  and  hence  appears  to  undergo 
fewer  anatomic  variations.  In  comparison  with  the  first  premolar 
its  crown  is  generally  slightly  smaller,  shorter,  rounder,  and  its  cusp 
less  pointed.  The  bucco-lingual  axis  is  directed  inward  and  slightly 
backward,  the  morsal  sulcus,  therefore,  slightly  backward  and  outward. 
It  appears  normally  to  possess  one  root  and  therefore  one  pulp  canal; 
but  two,  if  not  three  root  canals  are  quite  common.  In  the  latter  case 
a  bifurcation  of  the  buccal  root  has  occm-red,  more  or  less  along  its 
completed  length,  and  the  third  canal  opens  into  a  common  pulp  cavity 
with  the  other  two.  Frequent  connection  with  the  maxillary  sinus 
exists. 

The  Crown. — Of  all  fom-  surfaces  the  labial  or  buccal  is  slightly 
convex,  being  flatter  than  that  of  the  first  premolar  from  above  down- 
ward, and  more  convex  than  that  tooth  from  side  to  side.  It  is  diamond- 
shaped,  and  usually  free  from  vertical  ridges  or  grooves. 

Lingually  the  crown  matches  very  closely  the  corresponding  surface 
of  the  first  premolar.     Indeed  it  is  impossible  when  regarding  these 


DESCRIPTIVE  GROSS  AX  ATOMY 


33 


teeth,  which  have  been  removed  from  the  same  mouth,  to  determine, 
by  mere  inspection  of  the  Hngiial  sm-faces,  which  is  the  first  or  which 
is  the  second  premolar.  If  there  is  a  difference,  it  is  that  the  secoad 
has  a  romider  cusp.  For  the  size  of  the  tooth  the  upper  border  of  this 
surface  is  wider  antero-posteriorly  and  less  curved  than  obtains  in  the 
former. 

Of  the  mesial  surface  the  convexity  is  not  remarkable,  but  distally 
it  is.  Their  upper  borders  pass  almost  imperceptibly  into  the  Ime 
of  the  neck  of  the  tooth. 

The  morsal  siuface  resembles  that  of  the  first  premolar.  It  is  subject 
to  greater  variations,  however;  its  sulcus  is  shallower  and  shorter  than 
that  there  seen.  Frequently  three  slight  elevations  extend  outward 
from  the  sulcus,  separated  by  foiu  short,  narrow  grooves,  of  which  the 
middle  are  the  most  pronounced.  This  divides  the  surface  into  several 
tubercles;  as  many  as  five  may  be  present.  It  is  this  fact  which 
serves  on  occasion  to  differentiate  this  tooth  from  the  first  premolar. 
The  sulcus  may  bifiucate  at  its  anterior  extremity  and  thus  produce 
another  tubercle,  which  may  sometimes  attain  the  size  of  a  definite 
cusp. 

The  plane  of  the  neck  is  normally  horizontal. 

The  root  is  generally  A'ery  conical  in  longitudinal  outline.  Trans- 
versely flattened,  it  exhibits  btit  seldom  the  definite  deep  grooves 
associated  with  its  neighbors.  It  is  not  often  deflected,  but  may  be 
bifurcated  and  possess  three  root  canals. 

The  pulp  cavity  is  large  in  a  buccolingual  section  and  extremely 
narrow  in  a  mesiodistal  section.  Its  cornua  do  not  extend  far  mto  the 
cusps  of  the  tooth.    Of  the  two  the  outermost  is  the  greater. 


A  B 

Tig.    7. — Maxillary  second  premolar.     A.  buccal  surface  : 

surface:  D,  bucco-lingual  section. 


mesial  surface;   C,  dista 


Calcification  begins  durmg  the  fiith  year.  The  apical  foramen  is 
closed  dm-ing  the  eleventh  to  the  twelfth  year,  eruption  taking  place 
at  the  tenth  year  and  third  month. 

Length,  22  mm.;  mdtli.  5  mm. 

Identification. — It  is  impossible  to  determine  to  which  side  of  the 
mouth  this  tooth  belongs. 
3 


34  ANATOMY  OF  THE  TEETH  OF  MAN 

In  occlusion  the  tooth  comes  into  contact  with  both  the  mandibular 
second  premolar  and  first  molar;  in  the  first  instance  by  means  of  its 
internal  cusp  and  the  posterior  ridges  of  the  two  cusps  of  the  premolar 
and  in  the  other  by  means  of  its  internal  cusp  and  the  mesio-buccal 
and  mesio-lingual  cusps  of  the  molar. 

The  First  Molar. — Of  all  the  teeth  of  the  human  dentition  this 
is  undoubtedly  the  most  important.  From  the  viewpoints  of  palaeon- 
tology, histogenesis,  homology,  pathology,  surgery  and  orthodontics, 
it  may  be  regarded  as  the  most  interesting. 

The  sixth  tooth  from  the  midline  of  the  face  attains  the  highest  degree 
of  development  in  size  of  all  the  other  posterior  members  of  the  series. 
This  is  its  most  striking  feature,  for  the  morsal  surface  of  its  crown  is 
nearly  as  great  as  that  of  the  two  premolars  put  together.  It  is  in 
association,  through  its  anterior  buccal  root,  with  the  floor  of  the 
antrum,  and  communicates  with  the  cavuvi  oris  by  means  of  its 
palatine  root  and  vestibulum  oris  by  means  of  its  buccal  root.  Obliquity 
of  the  crown  is  always  accompanied  by  marked  obliquity  of  the  roots. 
It  presents  for  examination  a  crown,  neck  and  three  roots. 

The  crown  exhibits  five  surfaces:  (i)  buccal  or  external,  (ii)  lingual 
or  palatine,  (iii)  mesial,  (iv)  distal,  and  (v)  morsal  or  occlusal. 

Quadrilateral  in  outline  the  buccal  surface  extends  in  the  antero- 
posterior diameter  a  distance  fully  twice  that  of  the  same  diameter 
of  either  of  the  premolars,  while  its  vertical  measurements  are  less 
than  those  of  the  same  tooth.  It  is  slightly  convex  in  both  directions 
and  is  frequently  divided  into  two  unequal  parts  by  a  perpendicular 
groove  which  begins  at  a  slight  distance  below  the  cervical  margin. 
Its  upper  border  is  short  and  straight.  Its  lower  border  is  distinguished 
by  two  similar-sized  curves — the  external  portions  of  the  buccal  cusps 
— of  which  the  convexities  look  downward. 

The  lingual  surface  resembles  the  preceding  to  some  extent,  the  main 
points  of  difference  being  the  flatter  inferior  border,  the  rounder  char- 
acter of  the  angles  of  the  same  and  the  marked  prominence  of  the 
vertical  groove  which  often  curves  backward  in  its  lower  part.  The 
distal  portion  of  this  surface  is  much  more  convex  than  the  mesial. 

Roughly  rhomboidal  in  outline  the  mesial  extensive,  flat  surface 
possesses  on  its  lower  palatine  aspect  a  pronounced,  highly  convex 
slope  downward  and  forward.  Its  upper  border  occupies  a  horizontal 
plane,  but  the  lower  border  is  deeply  indented  near  the  middle  and 
internally  carried  considerably  downward. 

Unlike  the  former  the  distal  quadrilateral  surface  is  more  generally 
convex  in  both  directions,  the  convexity  being  accentuated  toward 
the  palatine  side.  It  is  free  from  grooves,  and  its  junction  with  the 
neck  is  hardly  perceptible. 


DESCRIPTIVE  GROSS  ANATOMY  35 

The  morsal  surface  in  outline  is  roughly  quadrilateral,  with  rounded 
angles.  It  possesses  four  cusps,  an  obHque  ridge  and  two  main  sulci  or 
fissures.  According  to  their  position  so  are  the  cusps  named.  They  are 
called  the  antero-external,  or  mesio-buccal,  the  postero-external,  or 
disto-buccal,  the  antero-internal,  or  mesio-lingual,  and  postero-internal, 
or  disto-lingual. 

Of  these  the  largest,  most  pyramidal  and  most  prominent,  is  the 
antero-internal  cusp.  It  is  joined  to  the  postero-internal  cusp  by  the 
oblique  ridge,  which,  near  the  middle,  is  traversed  by  a  slight  depression, 
amounting  almost  to  a  groove.  These  two  cusps  are  separated  from 
the  other  two  by  the  anterior  and  posterior  sulci,  the  former  short, 
deep,  bending  at  its  middle  at  an  acute  angle,  and  thus  passing  at  first 
from  without  inward  in  a  straight  line,  and  then  suddenly  bending 
forward;  and  the  other  beginning  near  the  middle  of  the  surface, 
sometimes  in  a  pit,  and  running  inward  and  slightly  forward.  The 
antero-external  cusp  is  somewhat  triangular  in  outline  and  the  postero- 
internal considerably  flattened  from  side  to  side  and  from  before  back- 
ward. With  regard  to  size  it  is  thus  obvious  that  the  dimensions  of 
the  individual  cusps  decrease  in  the  following  order:  antero-internal, 
antero-external,  postero-external  and  postero-internal.  A  fifth  cusp 
may  be  present  as  an  elevation  of  the  cingulum  at  the  side  of  the 
anterior  internal  cusp. 

The  neck  occupies  a  horizontal  plane  and  is  unmarked  by  any  notable 
deviations  from  a  straight  line.  In  section  the  tooth  is  rhomboidal  in 
outline  at  the  neck  and  is  also  more  extensive  on  the  lingual  than  on 
the  opposite  side. 

The  Roots. — ^This  tooth  possesses  three  roots:  (1)  The  anterior 
buccal  root  is  broad  in  the  bucco-lingual  direction,  much  flattened  and 
cone-shaped,  its  central  axis  looking  upward  and  slightly  outward  and 
forward.  It  is  often  grooved,  especially  on  its  inner  side;  hence  two 
root  canals  may  exist,  both  of  which  terminate  in  a  common  apical 
foramen.  (2)  The  posterior  buccal  is  considerably  shorter  and  smaller 
than  the  foregoing,  probably  normally  more  divergent,  slightly  grooved, 
and  consequently  less  likely  to  contain  two  root  canals.  (3)  The  pala- 
tine root  is  a  prominent  feature  of  this  tooth.  Very  divergent,  and  thus 
ensuring  great  stability  and  strength  in  its  articulation  with  the  maxilla, 
it  is  the  least  flattened  of  the  three.  It  is  frequently  deflected  and 
twisted.  It  measures  approximately  half  an  inch  in  length,  the  lengths 
of  the  others  being  about  three-eighths  inch. 

The  pulp  cavity  closely  follows  in  its  outline  the  shape  of  the  crown. 
At  its  roof  it  has  three  cornua,  each  extending  somewhat  into  each 
cusp,  and  on  the  floor  or  "  infundibulum"  the  three  openings  of  the  root 
canal,  that  on  the  palatine  side  being  cylindrical,  the  others  laterally 
flattened. 


36 


ANATOMY  OF  THE  TEETH  OF  MAN 


Calcification  occurs  in  the  first  instance  in  about  the  eighth  month 
of  intra-uterine  Hfe  and  is  completed  during  the  eleventh  or  twelfth 
year,  eruption  taking  place  at  the  sixth  year  and  sixth  month. 


A  B  c  D 

Fig.   8. — Maxillary  first  molar.     A,   buccal  surface;  B,   mesial  surface;   C,   lingual  or 
palatal  surface;  D,  bucco-lingual  section. 


Length. — From  the  apex  of  the  palatine  root  to  the  most  prominent 
part  of  the  crown  is  22  mm.,  of  the  buccal  root  to  the  anterior  part 
of  the  internal  border  21  mm.,  and  of  the  disto-buccal  root  to  the 
posterior  part  of  the  external  border  19  mm. 

Identification. — ^The  end  of  the  oblique  ridge  nearest  the  observer 
will  point  to  the  side  to  which  the  tooth  belongs  if  the  tooth  is  held 
crown  uppermost  and  the  palatine  root  away  from  him. 

Occlusion. — ^The  mesio-buccal  cusp  is  received  into  the  central  sulcus 
of  its  lower  congener,  the  disto-buccal  cusp  into  the  disto-lingual  and 
disto-buccal  cusps  and  the  mesio-buccal  and  mesio-lingual  cusps  of  the 
mandibular  second  molar. 

The  Second  Molar. — Intermediate  in  size  between  the  first  and 
third  molars,  this  tooth,  in  general,  follows  the  architectural  plan  of 
the  first-named,  particularly  on  the  buccal  portions  of  crown  and  roots. 
The  greatest  deviation  in  pattern  from  the  first  molar  is  to  be  found  on 
the  lingual  side.  The  opening  of  Stenson's  duct  is  usually  opposite  this 
tooth.  This  is  the  seventh  tooth  from  the  front  of  the  mouth.  It  has 
a  crown,  neck  and  three  roots. 

The  coronal  portion  of  the  tooth  is  smaller,  less  quadrilateral  in  out- 
line, and  its  usual  features  more  pronounced  than  the  former;  thus 
the  buccal  cusps  are  separated  by  deeper  sulci  and  hence  appear  to  be 
more  pronounced  than  in  the  first  molar. 

The  buccal  surface  is  flattened  from  above  downward  and  slightly 
convex  from  side  to  side.  Often  crossed  by  a  broad  horizontal  depres- 
sion, it  is  fairly  quadrangular  in  outline,  its  longest  border  being  the 
inferior  which,  like  that  of  the  first  molar,  is  divided  by  a  fissure  into 
two  uneven  parts,  and  is  doubly  curved  on  account  of  the  elevations 
of  the  buccal  cusps. 

The  most  noticeable  feature  on  the  lingual  side  is  the  marked  sloping 


DESCRIPTIVE  GROSS  ANATOMY 


37 


of  the  distal  part  and  the  very  sHght  elevation  of  the  line  of  the  lower 
border.    It  is  thus  dissimilar  to  what  obtains  in  the  first  molar. 

The  mesial  surface  is  considerably  broader  in  its  bucco-lingual 
diameter  than  its  height.  It  is  slightly  convex  and  shelves  off  tow^ard 
the  inner  side. 

The  distal  surface  is  extremely  convex  in  both  directions  and  short 
in  the  superior  and  inferior  diameter.  In  both  cases  the  upper  border, 
represented  by  the  neck,  is  practically  a  straight  line,  while  the  lower 
border  is  very  diversified  in  this  respect,  particularly  on  the  distal  side. 

Differing  in  a  remarkable  degree  from  that  of  the  first  molar,  the 
morsal  surface  of  this  tooth  presents  usually  the  four  cusps  of  the  typi- 
cal molar,  but  in  many  instances  three  cusps  only  are  seen,  viz.,  antero- 
external,  postero-external  and  internal.  When  four  are  present  they 
are  the  homologues  of  those  of  the  first  molar.  The  large  antero- 
internal  cusp  is  united  with  the  postero-internal  by  an  inconspicuous 
oblique  ridge,  which  is  commonly  traversed  by  a  shallow  sulcus.  The 
two  outer  cusps  exhibit  the  usual  mammilliform  shapes  of  a  typical 
molar.  They  are  separated  by  a  deep  fissure  which  ends  at  a  point 
near  the  center  of  the  buccal  surface.  The  antero-internal  cusp  is 
frequently  fused  to  the  postero-internal  cusp,  the  two  forming  a  large 
irregular  eminence  with  pointed  extremity  and  sloping  sides.  A 
vertical  depression,  amounting  sometimes  to  a  fossa  or  pit,  may  here 
be  seen. 


A  B  C  D 

Fig.  9. — Maxillary  second  molar.     A,  buccal  surface;  B,  mesial  surface;  C,  distal  surface; 

D,  bucco-lingual  section. 


The  neck  lies  in  a  horizontal  plane  and  probably,  when  compared 
with  that  of  the  first  molar  is  somewhat  more  constricted. 

The  Roots. — ^The  divergency  of  the  three  roots  of  the  first  molar 
are  not  so  marked  in  this  tooth.  Of  smaller  build,  there  is  a  tendency 
for  their  union,  especially  of  the  palatine  and  the  anterior  buccal. 
Obliquity  of  the  crown  frequently  obtains,  with  consequent  obliquity 
of  the  roots.    Deflection  backward  of  all  three  is  quite  common. 

Pulp  Cavity. — ^The  coronal  part  is  broad  in  the  bucco-palatine  direc- 
tion, narrow  in  the  other.  The  floor  of  the  cavity  is  fiat  or  depressed. 
The  root  canals  are  exceedingly  fiattened  from  side  to  side. 


38  ANATOMY  OF  THE  TEETH  OF  MAN 

Calcification  commences  at  the  fifth  year,  being  completed  between 
the  sixteenth  and  eighteenth.  The  tooth  begins  to  erupt  about 
the  end  of  the  eleventh  year. 

Length,  22  mm.;  width,  11  mm. 

Identification,  as  in  the  first  molar. 

Occlusion. — ^The  mesio-buccal  cusp  occludes  with  the  central  part 
of  the  morsal  surface  of  the  mandibular  second  molar  and  the  disto- 
buccal  cusp  with  both  the  distal  cusps  of  the  second  molar  and  the 
mesial  cusps  of  the  third  molar. 

The  Third  Molar. — ^More  variations  in  size,  shape,  position  and 
anatomic  features  of  the  crown  and  roots  exist  in  this  than  in  any 
other  member  of  the  dental  series.  Frequently  suppressed  it  is  the 
smallest  of  the  three  molars  and  totally  dissimilar  in  pattern  to  the 
first  molar.    The  crown  presents  five  surfaces  for  examination. 

Buccally  there  is  a  close  resemblance  to  the  corresponding  surface 
of  the  second  and  first  molars.  It  is,  however,  more  convex  in  both 
directions,  particularly  from  side  to  side;  less  extensive  in  the  mesio- 
distal  diameter  and  its  lower  border  less  distinctive  and  more  rounded. 
A  vertical  shallow  groove  divides  it  into  two  unequal  parts,  of  which 
the  anterior  is  the  greater.  The  upper  border  is  flat,  the  angles  round, 
especially  that  on  the  disto-buccal  side. 

On  the  lingual  side  the  tendency  to  a  shelving  or  sloping  of  the  distal 
portion,  noticed  in  the  middle  molar,  is  much  more  accentuated  here. 
The  whole  surface  is  slightly  convex  from  above  downward,  but  later- 
ally this  convexity  is  greatly  pronounced. 

The  mesial  surface  is  broad  and  flat,  and  when  the  tooth  is  in  situ 
is  close  up  against  the  distal  surface  of  the  second  molar,  thus  con- 
siderably reducing  the  capacity  of  the  interproximate  space. 

Distally  the  crown  is  markedly  convex,  narrower  from  above  down- 
ward than  in  a  lateral  direction. 

The  morsal  surface  of  the  crown,  on  comparison  with  the  other  molars 
is  smaU,  quadricuspid  in  about  50  per  cent,  of  cases,  and  tricuspid 
in  about  50  per  cent,  of  cases,  and  notable  in  the  absence  of  any 
deep  sulci,  fissures  or  elevated  cusps.  In  the  tricuspid  form  the  internal 
cusp  is  the  largest,  the  postero-external  the  smallest.  The  crown  is 
frequently  divided  into  seven  or  eight  tubercles,  each  separated  by 
short,  shallow  and  wide  grooves;  each  also  passing  in  every  direction 
from  a  short,  central,  deep  sulcus  running  across  the  antero-posterior 
diameter  of  the  tooth. 

The  neck  is  more  constricted  on  the  distal  than  the  mesial  surface. 
It  lies  in  a  horizontal  plane. 

Possessing  normally  three  roots,  which  may  be  separate  and  some- 
what divergent,  or  confluent,  as  usually  happens — roots  which  are 


DESCRIPTIVE  GROSS  ANATOMY 


39 


short,  small,  deflected  backward— this  tooth  may  exhibit  at  times 
four,  five  or  six  roots.  The  obliquity  of  the  crown  in  these  conditions 
is  repeated  in  the  obliquity  of  the  roots,  which  are  often  misshapen  and 
tortuous,  the  palatal  root  or  roots  being  the  most  inconspicuous  of  all. 


Fig.  10. — -Maxillary  third  molar. 


B  CD 

A,  buccal  surface;  B,  palatal  surface;  C,  mesial  surface; 
D,  distal  surface. 


Triangular  in  outline  and  in  shape  the  pulp  cavity  varies  just  as 
much  as  the  pattern  of  the  crown.  When  triangular  in  outline  the 
buccal  wall  is  the  shortest;  its  " infundibulum"  or  base  is  absent;  the 
orifices  of  the  root  canals  close  together  and  exceedingly  minute. 

Calcification  begins  dm-ing  the  ninth  year,  is  completed  between  the 
eighteenth  and  twentieth  years  and  the  tooth  begins  to  erupt  at  about 
the  eighteenth  to  twentieth  year. 

Length,  20  mm.;  width,  11  mm. 

Identification. — Can  be  effected  by  placing  the  tooth  in  the  position 
described  for  the  first  molar,  when  the  flattened  mesial  surface  of  the 
crown  will  point  to  the  side  to  which  the  tooth  belongs. 

Occlusion. — In  this  the  only  tooth  of  the  maxillary  series  occluding 
with  one  mandibular  tooth,  the  large  central  sulcus  accommodates 
the  external  and  distal  cusps  and  thus  slightly  overlaps  the  tooth  on 
the  buccal  as  well  as  the  distal  side. 

2.  The  Mandibular  Teeth. — ^The  First  Incisor. — Situated  on  either 
side  of  the  alveolar  process  of  the  mandible  at  the  symphysis  menti, 
which,  in  the  junction  of  the  two  halves  of  the  bone,  as  a  rule,  leaves 
no  traces  in  fully-formed  conditions,  this  tooth  is  the  homologue  of  the 
first  mandibular  incisor  in  anthropoid  apes  and  is  the  corresponding 
tooth  in  occlusion  with  its  maxillary  namesake.  It  is  probably  less 
variable  in  pattern  and  situation  than  any  other  tooth,  and  in  the 
absence  of  a  tendency  to  formation  of  a  cingulum,  differs  thus  very 
markedly  from  its  congener  in  the  upper  jaw.  It  possesses  a  crown, 
neck,  root  and  pulp  cavity. 

The  crown  is  well  proportioned.  Fashioned  like  a  fiattened  cone  and 
thus  chisel-shaped,  smooth  with,  at  times,  obvious  imbrication  lines 
on  the  triangular  labial  side,  it  is  more  convex  from  above  downward 


40 


ANATOMY  OF  THE  TEETH  OF  MAN 


than  from  side  to  side,  being  devoid  of  a  perpendicular  groove.  It  is 
broad  at  its  superior  or  incisive  edge,  which  at  birth  is  often  sur- 
mounted by  three  tubercles,  as  in  the  maxillary  teeth,  and  rapidly 
narrows  as  it  approaches  the  very  inconspicuous  inferior  or  gingival 
border. 

The  lingval  surface  is  concave  in  both  directions,  that  from  side  to 
side  being  particularly  noticeable.  The  triangular  proportions  of  the 
labial  surface  appear  here,  but  are  more  accentuated  on  account  of  the 
somewhat  greater  elevation  of  the  sides  of  the  triangle,  particularly  at 
its  apex.    This  surface  is  nearly  always  free  from  depressions  or  grooves. 

Mesially,  a  flat  triangular  surface,  with  its  indistinguishable  base 
below  at  the  gingival  margin,  and  its  apex  at  the  mesial  angle  of  the 
incisive  edge,  it  exhibits  generally  the  same  features  on  th.e  distal 
aspect  of  the  crown,  which,  however,  may  be  slightly  concave  in  the 
vertical  and  a  little  convex  in  the  transverse  direction.  The  mesial 
surface  is  slightly  larger  than  that  on  the  opposite  side. 

The  borders  and  angles  are  similar  to  those  described  in  connection 
with  the  maxillary  tooth. 

The  neck  is  slightly  constricted  and  therefore  inconspicuous.  It  is 
curved  downward  on  the  labial  and  lingual  sides. 

The  root  is  long,  narrow  in  the  antero-posterior  diameter,  but  broad 
and  flattened  in  the  other  direction.  Its  anterior  side  is  slightly  longer, 
less  convex,  and  broader  than  the  other.  The  flattening  of  the  sides 
may  amount  at  times  to  a  shallow  grooving  extending  nearly  all  the 
length  of  the  distal  aspect  of  the  root. 


A  B  CD 

Fig.    11. — Mandibular  first   incisor.     A,  labial  surface;  B,  lingual   surface;  C,   mesial 

surface;  D,  mesio-distal  section. 


The  outline  of  the  pulf  cavity  follows  that  of  the  external  portion  of 
the  tooth,  being  quite  narrow  from  side  to  side,  and  broad  in  labio- 
lingual  section.  The  root  canal  may  be  bifurcated,  but  this  is  not  a 
usual  condition. 

Calcification  of  this  tooth  begins  diu-ing  the  first  twelve  months  after 
birth,  and  the  apical  foramen  is  formed  by  the  tenth  year.  In  30  per 
cent,  of  cases  the  tooth  is  erupted  about  the  sixth  year  and  sixth  month. 


DESCRIPTIVE  GROSS  ANATOMY 


41 


Extreme  length,  23  mm.;  extreme  width,  6  mm. 

Identification. — In  a  horizontal  position,  with  root  toward  the 
observer,  the  longer  side  of  the  tooth  indicates  the  side  which  it  occu- 
pies when  in  situ. 

Occlusion  occm-s  on  the  labial  side  with  the  lingual  aspect  of  the  crown 
of  the  maxillary  first  incisor. 

The  Second  Incisor. — ^A  reversal  of  the  anatomic  characteristics 
of  the  upper  incisor  is  found  here  in  the  fact  that  while  the  maxillary 
second  incisor  is  considerably  smaller  than  the  first  incisor  the  mandib- 
ular second  incisor  is  larger  than  that  just  described.  In  some  jaws 
there  is  great  disparity  in  size,  but  in  well-constructed  typical  instances 
difl^erences  in  the  dimensions  of  the  two  are  not  so  marked. 

Crown. — ^Triangular  in  outline,  the  labial  surface  is  broad  at  the  base 
and  incisive  edge  and  narrow  at  the  gingival  margin,  but  the  angles 
are  not  so  acute  as  in  the  first  incisor.  The  surface  is  a  little  more 
convex  in  both  directions  than  that  tooth.    It  has  a  long  upper  border. 

Lingually  the  surface  is  the  counterpart  of  the  first  incisor.  In  some 
cases  the  concavities  are  slightly  more  pronounced.  There  is  no 
attempt  at  the  formation  of  an  internal  cusp,  as  in  the  upper  tooth, 
consequently  no  pits  or  fissures  are  here  observed. 

The  mesial  surface  is  long  and  either  flattened  or  slightly  concave. 
Its  superficies  is  trangular,  with  the  base  below  and  apex  above,  form- 
ing with  the  incisive  edge  an  acute  angle. 


A  B  C  D 

Fig.  12. — ^Mandibular  second  incisor.     A,  labial  surface;    B,  lingual  siu-face;  C,  mesio- 
distal  section;  D,  labio-lingual  section. 


Bistally  the  surface  is  short,  flat,  or  slightly  concave,  and  its  angle 
at  the  incisive  edge  nearly  a  right  angle. 

The  Neck. — ^The  coronal  and  radicular  portions  blend  imperceptibly 
into  one  another  and  the  junction  of  the  two  usually  cannot  be  seen 
except  on  the  lingual  side. 

The  root  is  longer  in  this  than  in  the  preceding  tooth.  It  is  straight, 
narrow  from  before  backward,  and  broad  from  side  to  side.    A  median 


42  ANATOMY  OF  THE  TEETH  OF  MAN 

vertical  groove  often  extends  down  its  entire  length  on  both  sides,  and 
is  generally  more  marked  on  the  side  toward  the  canine. 

The  pulp  cavity  resembles  that  of  the  first  incisor,  being  extremely 
flattened  about  the  midportion  of  the  root,  but  cylindrical  in  the 
coronal  and  apical  regions.  In  its  coronal  parts  it  extends  somewhat 
suddenly  to  form  a  not  inconsiderable-sized  cavity. 

Calcification,  root  formation  and  eruption  occur  at  the  ages  of  the 
first  year,  tenth  to  twelfth,  and  seven  and  a  half  years  respectively. 

Length,  24.5  mm.;  width,  6  mm. 

Identification  as  in  the  mandibular  first  incisor. 

Occlusion  takes  place  with  the  lingual  aspect  of  the  crowns  of  the 
maxillary  first  and  second  incisors. 

The  Canine. — ^This  tooth  affords  a  good  example  of  the  transitional 
type  of  organ  from  the  chisel-like  incisive  crown  of  the  anterior  teeth 
to  the  semi-molariform  pattern  of  the  posterior  teeth.  The  intermediate 
character  of  the  coronal  features  here  is  justly  noticeable.  Occasion- 
ally it  may  be  an  enormous  tooth,  especially  in  length.  In  tj^pical 
specimens  the  buccal  aspect  of  its  crown  has  a  greater  superficies  than 
any  other  mandibular  tooth. 

Crown. — On  its  buccal  side  the  crown  presents  an  extensive  surface 
for  examination.  A  vertical  parallelogram,  its  upper  border  is  pointed, 
the  apex  being  nearer  the  front  than  the  back,  thus  dividing  the  incisive 
edge  into  two  unequal  parts,  of  which  the  posterior  may  measure  twice 
the  length  of  the  anterior.  The  surface  is  convex  in  both  directions, 
more  in  the  vertical  than  in  the  horizontal.  A  slight  perpendicular 
ridge  of  enamel  may  frequently  be  found  here.  The  lower  border  is 
in  a  straight  line. 

On  the  lingual  surface  a  large,  shallow  concavity  appears.  This  is 
deeper  from  side  to  side  than  above  downward.  The  floor  of  the 
cavity  is  not  smooth  but  overrun  sometimes  by  one  or  more  vertical 
ridges,  separated  by  grooves  of  varying  depth  and  length.  The  borders 
of  this  surface  are  much  rounded,  especially  at  their  lower  part,  where 
an  elevation  of  the  cingulum  may  occasionally  be  seen.  A  canine  with 
a  lingual  cusp  always  belongs  to  the  upper,  never  to  the  lower  jaw. 

The  mesial  surface  is  triangular  in  outline,  being  similar  in  shape  and 
size  to  the  distal  surface  of  the  second  incisor.  It  is  flat  and  extensive 
and  passes  imperceptibly  over  to  the  root  by  means  of  an  inconspicuous 
neck. 

The  distal  surface  differs  in  a  marked  degree  from  that  last  described, 
in  that  its  surface  is  convex  in  both  directions,  particularly  the  vertical, 
and  joins  with  the  sloping  upper  border  of  the  crown  to  make  a 
prominent  "contact  point"  with  the  neighboring  tooth.  It  bends  in 
very  suddenly  toward  the  constricted  neck,  and  thus  is  produced  one 
side  of  an  unusually  large  interproximate  space. 


DESCRIPTIVE  GROSS  ANATOMY 


43 


The  most  conspicuous  part  of  the  neck  is  on  the  labial  and  lingual 
surfaces. 

The  root  assumes  great  dimensions.  It  is  broad  at  the  cervical  margin, 
is  usually  straight,  i.  e.,  has  the  same  longitudinal  axis  as  the  whole 
of  the  tooth,  but  in  every  instance  is  inclined  to  be  deflected  somewhat 
toward  the  distal  side.  Shallow  grooves  exist  mesially  and  distally. 
Of  the  four  aspects  of  the  root  the  lingual  and  the  mesial  are  the 
narrower.  Bifurcation  of  the  root  canal  is  fairly  common,  and  the 
development  of  an  extra  lingual  root  not  infrequent. 

The  pulp  cavity  bears  some  resemblance  in  shape  to  that  of  the 
maxillary  canine.  It  is  large  in  the  labio-lingual  diameter,  narrow  and 
tube-like  in  the  mesio-distal  section. 


A  B  CD 

Fig.    13. — Mandibtdar  canine.     A,  labial  surface;  B,  lingual  surface;   C,  mesio-distal 
section;  D,  labio-lingual  section. 


Calcification  begins  with  the  third  year,  is  concluded  at  about  the 
twelfth  or  thirteenth,  and  the  tooth  begins  to  erupt  in  company  with 
its  maxillary  confrere  before  calcification  is  complete,  about  the  eleventh 
year  and  third  month. 

Length,  31   mm.;  width,   12  mm. 

Identification. — ^Placed  horizontally,  with  root  toward  the  observer, 
the  shorter  of  the  two  portions  of  the  cutting  edge  is  directed  toward 
the  side  to  which  the  tooth  belongs. 

In  occlusion  the  labial  surface  is  in  contact  with  the  lingual  surface 
of  the  maxillary  canine,  and  also  of  the  distal  portion  of  the  same 
surface  of  the  second  incisor. 

The  First  Premolar. — Most  interesting  of  all  teeth  from  a  mor- 
phological point  of  view,  this  tooth,  even  better  than  the  preceding, 
exhibits  and  illustrates  a  gradational  type  between  a  tooth,  with  a 
thin,  incisive  edge  and  that  with  a  broad  morsal  surface.  Though 
there  are  no  two  teeth  absolutely  alike  in  shape  and  pattern,  there  is 
generally  a  close  similarity  in  the  design  of  the  corresponding  teeth  in 
each  half  of  the  jaw.    A  variation  exists  here,  for  the  two  first  pre- 


44  ANATOMY  OF  THE  TEETH  OF  MAN' 

molars  may  be  entirely  different,  one  presenting  a  crown  like  an  under- 
developed canine,  the  other  molariform  in  general  appearance. 

The  typical  crown  imitates  the  architectural  features  of  the  maxillary 
canine,  as  will  be  described  below. 

Externally  the  buccal  coronal  surface  closely  resembles  that  of  the 
anterior  tooth.  It  is  less  high,  however,  and  approaches  a  pentagonal 
form  with  a  pointed  upper  extremity.  It  is  markedly  convex  from  side 
to  side;  less  so  in  the  other  direction.  Its  upper  border  is  like  that  of 
the  canine. 

The  lingual  surface  is  very  inconspicuous.  It  is  convex  from  before 
backward,  less  so  from  above  downward.  It  is  four  times  as  long  as  it 
is  broad,  and  surmounted  by  a  tubercle  which  extends  over  the  coronal 
surface. 

The  mesial  convex  surface  is  more  extensive  than  the  opposite, 
sloping  obliquely  inward  from  its  junction  with  the  buccal  surface. 

The  area  of  the  distal  surface  is  much  smaller  than  that  on  the  mesial 
side,  due  to  the  encroachment  of  the  backward  slope  of  the  morsal 
surface  of  the  tooth. 

Morsally,  a  unique  appearance  is  presented  by  the  absence  or  sup- 
pression of  the  internal  cusp,  so  conspicuous  in  the  maxillary  premolar. 
That  the  internal  cingulum  is  raised  on  this  surface  is  obvious,  for 
frequently  not  only  does  it  form  a  thickened  tubercle,  but  a  marked 
ridge,  which  passes  immediately  upward  to  terminate  in  the  apex  of 
the  incisive  edge,  and  is  derived  from  the  same  elevated  crest.  Fur- 
ther, from  the  base  of  this  ridge  also,  frequently  short  thick  bands 
elevate  themselves  upward  and  forward  and  upward  and  backward. 
The  consequence  of  the  production  of  these  ridges  is  the  formation  of 
deep  pits  on  the  mesial  and  distal  aspects  of  the  crown.  Of  these 
the  latter  is  the  deeper.  This  triangular  surface  may  exhibit  four  or 
five  tubercles,  or  two  cusps,  one  prominent,  the  other  less  pronounced. 

The  neck  occupies  a  horizontal  plane.  It  is  frequently  almost 
invisible,  owing  to  its  lack  of  constriction. 

On  the  faces  of  the  root,  which  follows  with  but  little  deviation  the 
line  of  the  central  longitudinal  axis  of  the  tooth  itself,  the  broader 
are  on  the  buccal  and  mesial  sides.  Grooves  existing  on  the  mesial 
and  distal  sides  may  be  deepened  to  such  an  extent  as  to  give  the 
appearance  of  the  bifurcation  or  the  production  of  a  third  root.  In 
the  case  of  the  latter  the  root  is  placed  in  an  antero-external  position. 

The  pulp  cavity  simulates  in  outline  the  general  contour  of  the  crown. 
A  small  cornu  may  insinuate  itself  toward  the  lingual  tubercle.  Usually 
the  pulp  chamber  is  a  slightly  flattened  cylinder.  In  the  case  of  an 
additional  root  or  roots  the  canals  are  cylindrical. 


DESCRIPTIVE  GROSS  ANATOMY 


45 


Calcification  begins  about  the  fourth  year.  The  apical  foramen  is 
completed  at  the  eleventh  to  the  twelfth  year,  eruption  taking  place 
at  the  ninth  year  and  tenth  month. 

Length,  25  mm.;  width,  7  mm. 

Identification. — In  a  vertical  position,  with  the  extremely  rounded 
labial  surface  of  the  crown  nearest  the  observer,  the  round  mesial 
surface,  with  its  fossa,  points  to  the  side  to  which  the  tooth  belongs. 

Occlusion.  The  mesial  and  coronal  surfaces  interdigitate  with  the 
distal  aspect  of  the  crowns  of  the  maxillary  canine  and  its  distal 
surfaces  with  the  inner  cusp  of  the  maxillary  first  premolar. 


A  B  c  D 

Fig.  14. — Mandibular  first  premolar.     A,  buccal  surface;  B,  lingual  surface;  C,  distal 
surface;  D,  labio-lingual  section. 


The  Second  Peemolae. — ^The  main  architectural  features  of  this 
tooth  are  entirely  different  from  those  just  described.  It  approxi- 
mates more  closely  that  of  the  upper  second  premolar,  save  that  in 
typical  specimens  it  is  smaller  in  every  particular.  The  crown  is  large, 
with  rounded  angles,  and  its  inner  portion  raised  more  nearly  on  a 
level  with  the  occlusal  surface  of  the  first  molar  than  in  the  anterior 
tooth. 

The  croum  possesses  five  surfaces.  Of  these  the  buccal  is  the  largest, 
being  almost  identical  in  shape,  size  and  contour  with  that  of  the  first 
premolar.  It  may  measure  a  little  less  in  the  vertical  direction.  The 
cusp  is  round. 

Lingually — a  fairly  convex  surface — the  crown  is  wider  from  before 
backward  than  from  above  downward,  and  thus  presents  the  outlines 
of  a  flat  parellelogram. 

Of  the  mesial  and  distal  surfaces  the  former  is  larger,  smoother  and 
more  flattened  than  the  latter,  the  presence  of  a  cusp  at  the  upper 
part  of  the  latter  giving  it  an  undue  prominence  over  that  of  the 
other  side. 

The  morsal  surface  is  somewhat  square  in  outline;  all  of  its  four 
borders  are  rounded,  its  cusps  and  tubercles  less  marked  than  those  of 
the  upper  tooth.  The  sulcus  is  fairly  deep,  runs  from  before  backward, 
and  divides  behind  into  two  and  sometimes  three  branches,  enclosing 


46 


ANATOMY  OF  THE  TEETH  OF  MAN 


elevations  of  enamel  which,  not  being  pronounced  enough  to  designate 
as  cusps,  are  more  correctly  described  as  tubercles.  The  largest  of 
these  is  often  placed  most  distally. 

The  neck  is  but  slightly  discernible  on  its  convex  distal  side.  It  lies 
in  a  horizontal  plane. 

The  root  is  unusually  long  and  large.  Its  buccal  side  is  wider  than 
the  opposite  and  its  anterior  aspect  flat  or  slightly  convex,  its  distal 
surface  concave  or  grooved. 

The  pulp  cavity  possesses  two  marked  cornua,  of  which  the  larger 
is  contained  in  the  labial  cusp.  The  pulp  canal  is  single  and  much 
flattened  from  side  to  side. 


I' 


A  BCD 

Fig.  15. — Mandibular  second  premolar.     A,  buccal  surface;  B,  mesial  surface;  C,  mesio- 

distal  section;  D,  bucco-lingual  section. 


Calcification  begins  between  the  fourth  and  fifth  years,  is  com- 
pleted seven  years  later,  and  the  tooth  erupts  at  a  date  prior  to  its 
completion,  namely,  about  the  tenth  year  and  sixth  month. 

Length,  23  mm.;  width,  8  mm. 

Identification. — ^It  is  generally  almost  impossible  to  determine 
whether  the  second  premolar  belongs  to  the  right  or  the  left  side  of 
the  mandible. 

Occlusion. — ^This  tooth  occludes  with  the  maxillary  premolars,  its 
mesial  coronal  surfaces  coming  into  contact  with  the  distal  surfaces  of 
the  upper  first  premolar  and  its  distal  surfaces  with  the  mesial  aspects 
of  the  crown  of  the  second  premolar. 

The  First  Molar. — ^Upon  this  tooth  the  dentition  of  man  probably 
is  principally  dependent  for  the  greatest  stress  and  strain  in  the  dental 
arch,  its  position  in  the  middle  of  the  masticatory  field  giving  it  an 
importance  which  is  second  only  to  that  of  its  maxillary  homologue. 
It  possesses  a  considerable  degree  of  anatomical  interest  also,  for  its 
morsal  surface  presents  for  examination  a  larger  and  more  compli- 
cated arrangement  of  parts  than  obtains  in  any  other  tooth.  Its 
relations  to  the  sciences  of  palaeontology,  anthropology  and  biology, 
in  addition  to  those  of  surgery  and  orthodontics,  invest  it  with  a  degree 
of  interest  which  is  unique.     The  obliquity  which  is  so  common  a 


DESCRIPTIVE  GROSS  ANATOMY 


•47 


feature  of  the  crown  of  the  maxillary  molar  is  here  noticeable;  the 
tooth  is  therefore  more  or  less  variable  in  form. 

A  crown,  neck  and  two  roots  are  to  be  described. 

The  crown  has  five  surfaces:  mesial,  distal,  buccal,  lingual  and  morsal. 

The  mesial  surface  is  smooth  and  equally  convex  in  both  directions. 
It  has  a  curious  outline,  roughly  similar  to  that  of  an  isosceles  triangle 
with  an  extended  base  and  considerably  flattened  apex,  of  which  the 
outer  straight  line  bends  inw^ard  rather  more  than  the  opposite,  making 
a  more  acute  angle  at  its  junction  with  the  base  than  the  internal,  which 
contains  almost  a  right  angle.  Its  upper  surface  is  marked  by  the 
presence  of  two  shorter  and  smaller  apices — the  anterior  portions  of  the 
antero-external  and  antero-internal  cusps.  The  "contact  point"  of 
this  surface  is  to  the  outer  side  of  the  midline  and  about  midway 
between  the  neck  and  the  upper  border. 

Distally  the  siu-face  is  fairly  quadrangular  in  outline,  broader  in 
the  bucco-lingual  diameter,  and  relieved  by  the  elevation  of  the  distal 
surface  of  the  fifth  or  distal  cusp.  Thus  the  upper  border  presents 
three  elevations  of  varying  size,  of  which  the  most  distal  is  the  shortest 
and  most  conspicuous. 


A  B  c  D 

Fig.   16. — Mandibular  first  molar.     A,  buccal  surface;  B,  lingual  surface;  C,  mesial 

surface;  D,  distal  surface. 


Of  all  the  buccal  surfaces  of  the  teeth,  that  of  this  tooth  is  by  far  the 
largest.  It  frequently  measures  12  mm.  from  before  backw^ard,  approxi- 
mately about  3  mm.  longer  than  that  w^hich  obtains  in  the  upper 
tooth.  It  is  exceedingly  convex,  from  above  downward,  giving  the 
appearance  of  being  inclined  inward,  less  convex  from  side  to  side. 
In  outline  it  assumes  the  form  of  a  rough  parallelogram,  wdth  a  flat, 
straight  base  and  somewhat  divergent  sides,  and  an  indented  upper 
border  raised  into  three  points,  of  which  the  anterior  is  broad  and  round, 
the  middle  sharp  and  the  posterior  small  and  blunt.  A  groove  passes 
between  the  two  first  named  and  frequently  terminates  in  a  con- 
spicuous pit,  a  favorite  site  for  dental  caries. 

The  lingual  surface  resembles  somewhat  remarkably  the   buccal 


48  ANATOMY  OF  THE  TEETH  OF  MAN 

surfaces  of  the  maxillary  first  and  second  molars,  the  points  in  the 
upper  border,  however,  being  sharper  than  the  rounder  elevations 
in  the  last  named.  Its  smooth,  slightly  convex  area  is  contained 
in  a  fairly  regular  parallelogram,  of  which  the  upper  and  lower  sides 
are  the  longer.  A  pit  or  fossa  is  seldom,  if  ever,  noticeable  on  this 
surface. 

Morsally  this  tooth  presents  a  trapezoidal  figure  with  five  cusps 
and  five  fissures.  Of  all  the  sides  the  anterior  is  the  most  nearly 
straight,  the  distal  the  most  acute,  the  innermost  the  longest  and 
the  outermost  divided  into  two  even  parts.  The  cusps  are  named 
according  to  their  position:  (i)  Antero-external  or  mesio-buccal;  (ii) 
antero-internal  or  mesio-lingual ;  (iii)  postero-external  or  disto-buccal ; 
(iv)  postero-internal  or  disto-lingual;  (v)  distal.  The  chief  character- 
istics of  the  individual  cusps  are  as  follows:  mesio-buccal,  the  largest, 
most  rounded,  with  shelving  outer  part;  mesio-lingual,  the  most 
acutely  pointed;  disto-buccal,  narrow  from  front  to  back,  somewhat 
wedge-shaped,  with  blunt  apex;  disto-lingual,  short,  triangular,  fre- 
quently subdivided  into  three  small  tubercles  by  two  short  grooves- 
passing  inward;  and  distal,  small,  prismatic  in  outline  and  possessing 
an  acute  cusp. 

The  fissures  vary  greatly  in  depth,  direction  and  dimensions.  As 
they  are  situated,  so  are  they  named.  Thus,  taking  their  origin  from 
the  center  of  the  crown  the  anterior  separates  the  two  mesial  cusps,  and 
as  it  reaches  its  termination  often  bifurcates  widely  and  so  produces 
an  extra  cusp,  which  is  then  named  the  mesial  cusp;  the  j)osterior 
running  irregularly  backward  and  enclosing  in  its  bifurcation  the 
distal  cusp;  the  buccal  passing  directly  outward,  separating  the  two 
buccal  cusps  and  extending  over  the  ridge  to  the  pit  on  the  buccal 
side;  and  the  lingual,  separating  the  two  inner  cusps  and  terminating 
just  short  of  the  upper  border  of  the  lingual  surface.  The  short  fifth 
fissure  is  centrally  placed  and  unites  the  others  together. 

The  neck  is  usually  indistinct,  quadrangular  in  outline  and  in  the  same 
horizontal  plane. 

The  roots  are  two  in  number:  anterior  or  mesial,  and  posterior  or 
distal.  The  former  is  broad,  extremely  flattened  from  before  backward, 
slightly  deflected  backward,  somewhat  triangular  in  shape^  and  grooved 
on  both  sides,  that  on  the  distal  side  being  the  more  pronounced;  the 
latter  is  smaller,  more  nearly  straight,  narrower  and  grooved  on  its 
anterior  aspect. 

The  pulp  cavity  is  irregularly  square  in  its  coronal  portion,  with 
extensive  cornu  at  its  upper  corners.  There  is  no  cornua,  as  a  rule, 
beneath  the  distal  cusp.  Three  pulp  canals  are  frequently  found,  two 
in  the  mesial  root  and  one  in  the  distal.    Of  these  the  former  are  small, 


DESCRIPTIVE  GROSS  ANATOMY  49 

flattened  laterally;  the  latter  large  and  much  flattened  from  side  to 
side. 

Calcification  begins  during  the  eighth  month  of  intra-uterine  life. 
The  roots  are  completely  formed  by  the  ninth  to  the  tenth  years,  and 
eruption  takes  place  at  the  sixth  year  and  sixth  month. 

Length,  21  mm.;  width,  12  mm. 

Identification  can  be  efl^ected  by  holding  the  tooth  crown  uppermost, 
with  the  small  triangular  distal  cusp  away  from  the  observer,  the  pit 
on  the  buccal  surface  (or  the  very  rounded  character  of  the  latter  if 
there  is  no  pit)  points  to  the  side  opposite  to  that  to  which  the  tooth 
belongs. 

Occlusion. — ^The  mesio-buccal  cusp  occludes  with  the  distal  ridges  of 
both  cusps  of  the  maxillary  second  premolar,  and  the  mesio-buccal  and 
mesio-lingual  cusps  of  the  maxillary  first  molar;  and  its  disto-buccal 
cusp  with  the  central  part  of  the  morsal  surface  of  the  same  tooth. 

The  Second  Molar. — ^This  tooth  is  modeled  on  a  different  archi- 
tectural plan  from  that  of  the  preceding.  It  differs  in  the  facts  that  it 
is  smaller,  more  sjinmetrical  in  shape,  its  cusps  more  proportionally 
equal  in  size.  It  has  no  fifth  cusp  and  its  roots  are  closer  together 
than  in  the  first  molar. 

The  croicn  has  five  surfaces.  Mesially  the  surface  is  slightly  convex, 
square  in  outline,  with  its  superior  border  raised  into  two  blunt  points, 
the  sides  of  the  mesial  cusps.  The  lower  border  slopes  gently  downward 
and  outward.  On  the  distal  side  a  greater  convexity  of  the  surface  is 
observed  over  any  other.  Its  upper  border  is  nearly  horizontal,  being 
relieved  somewhat  by  the  presence  of  two  blmit  apices.  With  the 
exception  of  the  superior  surface  the  bnccal  aspect  of  the  crown  is  the 
largest  of  all.  Quadrangular  in  outline,  its  anterior  and  posterior 
borders  are  more  nearly  parallel  than  in  the  first  molar.  It  is  smooth 
and  convex  in  both  directions,  especially  the  vertical.  It  is  seldom 
disfigured  by  the  presence  of  a  pit  or  fossa.  The  lingual  surface  is 
broader  antero-posteriorly  than  vertically.  Slightly  convex,  it  presents 
a  similar  appearance  to  that  of  the  opposite  side.  The  occlusal  surface 
is  remarkable  for  the  regular  arrangement  of  its  constituent  parts. 
Its  four  cusps,  mesio-buccal  or  antero-external,  disto-buccal  or  postero- 
external, mesio-lingual  or  antero-internal,  and  disto-lingual  or  postero- 
internal, are  distinctly  uniform  in  character,  outline,  size,  shape  and 
height.  If  there  is  a  difference  the  mesio-buccal  cusp  is  the  most  impor- 
tant and  pronounced.  The  fissiu-es  emanate  from  a  common  central 
spot  in  the  middle  of  the  crown.  They  vary  slightly  in  depth,  run  in 
straight  lines,  pass  directly  forward  (mesial  fissure) ,  backward  (distal) , 
outward  (buccal),  and  inward  (lingual)  and  seldom  bifiu^cate  or  extend 
over  the  sides  of  the  crown. 
4 


50 


ANATOMY  OF  THE  TEETH  OF  MAN 


The  constriction  of  the  horizontally  placed  neck  is  unusually  marked. 

Similarly  to  the  first  molar  there  are  two  roots.  Generally  speaking 
they  are  smaller,  more  confluent  and  less  compressed  from  side  to  side 
than  those  of  the  aforementioned  tooth.  The  mesial  is  the  larger  and 
broader  and  deflected  somewhat  backward;  the  distal,  the  straighter 
and  frequently  the  shorter  and  narrower.  The  distal  root  is  not  grooved. 

The  pulj)  cavity  follows  in  shape  the  general  outline  of  the  crown;  the 
root  canals,  of  the  roots,  that  on  the  mesial  side  being  much  flattened 
laterally,  the  other  more  nearly  cylindrical. 


^ 

4^ 

"w 

} 

ABC  D 

Fig.  17. — Mandibular  second  molar.     A,  buccal  surface;  B,  lingual  surface;  C,  mesial 
surface;  D,  mesio-distal  section. 


Calcificatio7i  occupies  about  eleven  or  twelve  years,  the  first  signs 
appearing  at  the  fifth  year  and  the  apical  foramina  completed  by  the 
sixteenth  or  seventeenth  year.  Eruption  begins  about  the  eleventh 
year. 

Length,  23  mm.;  width,  11  mm. 

Identification. — ^A  typical  tooth  has,  as  already  indicated,  a  square 
crown.  If  such  a  tooth  is  held  crown  uppermost,  with  the  larger  root 
nearest  the  observer,  the  flatter  of  the  two  lateral  surfaces  will  point 
to  the  side  to  which  the  tooth  belongs. 

Occlusion. — ^The  mesio-buccal  cusp  occludes  with  the  disto-buccal 
and  disto-lingual  cusps  of  the  maxillary  first  molar,  and  the  mesio-buccal 
and  mesio-lingual  cusps  of  the  second  molar.  Its  disto-lingual  cusp 
interdigitates  with  the  central  part  of  the  morsal  surface  of  the  maxil- 
lary second  molar. 

The  Third  Molar. — Typical  examples  of  this  tooth  are  difficult  to 
find.  It  undergoes,  however,  fewer  variations  in  size  and  pattern  of 
crown  and  shape  of  roots  than  its  maxillary  congener.  In  a  well-devel- 
oped jaw  it  is  a  large  tooth;  even  in  a  small  jaw  it  is  still  a  relatively 
large  tooth.  While  not  subject  to  much  change  in  architectural  details 
it  is  frequently  misplaced,  and  its  surgical  affections  most  important 
in  their  induction  of  severe  systemic  and  general  disturbances. 

The  crown  occupies  nearly  the  upper  half  of  the  entire  superficies. 
This  is  more  noticeable,  perhaps,  on  its  distal  than  on  its  mesial  side. 


DESCRIPTIVE  GROSS  ANATOMY 


51 


The  mesial  surface  is  convex,  slopes  inward  and  is  higher  on  the 
internal  than  on  the  buccal  side.  The  upper  border  is  raised  into  two 
more  or  less  definite  projections  or  points. 

DistaUy  the  surface  is  markedly  convex.  The  amelo-cemental  junc- 
tion at  the  neck  is  fully  constricted.  This  surface  is  fairly  square  in 
outline,  and  its  upper  border  relieved  by  three  or  more  blunt,  variable 
points. 


A  BCD 

Fig.    18. — Mandibular  third  molar.     A,  buccal  surface;  B,  lingual  surface;   C,  mesial 

surface;  D,  distal  surface. 


The  buccal  surface  is  much  broader  than  deep.  It  is  very  convex, 
particularly  behind,  where  its  distal  angle  is  considerably  rounded. 
The  lingual  surface  is  broad  from  before  backward,  shallow  from  above 
downward,  the  line  of  its  upper  border  being  deeply  indented  in  the 
center. 

The  occlusal  surface  presents  many  varieties  of  shape,  outline,  size 
and  pattern.  It  may  be  rounded  or  flattened,  arched  or  tuberculate; 
it  may  be  roughly  hexagonal;  it  may  be  broader  antero-posteriorly 
than  bucco-lingually;  it  may  have  four,  five,  six,  seven  or  eight  cusps 
of  every  different  shape  and  size.  It  may  closely  simulate  the  pattern 
of  its  neighbor;  it  may  be  entire  dissimilar,  presenting  superficial  pits, 
grooves,  fissures,  fossse  and  the  like.  The  table-land  may  be  raised  up 
into  one  large  cusp  toward  the  lingual  side  of  this  surface  with,  at  its 
base,  numerous  tubercles,  which  sometimes  are  conical,  oval,  oblong, 
round  or  pointed.  Well-formed  teeth  exhibit  fissiues  which  run  in 
similar  directions  to  those  of  the  second  molar,  but  are  generally  shal- 
lower and  less  regular  in  general  character. 

The  cervical  margin  is  well  marked  and  nearly  horizontal. 

The  roots  are  diminutive  and  disproportionate  to  the  size  of  the 
crown;  inclined  somewhat  backward;  usually  confluent;  occasionally 
separate  and  in  rare  instances  allowing  the  passage  of  the  mandibular 
nerve  between  them.  Usually  two  are  present,  but  there  may  be  three 
or  even  four,  all  of  which  rapidly  taper  down  at  their  apices  to  a  fine 
point. 

The  shape  of  the  common  'pulp  cavity  is  governed  by  that  of  the 


52 


ANATOMY  OF  THE  TEETH  OF  MAN 


crown.   The  canals  are  small  and  irregular,  depending  upon  the  general 
shape  and  character  of  the  roots  themselves. 


Fig.  19. — ^Vertical  section  through  the  left  maxilla  and  mandible  of  man,  with  the 
external  alveolar  plates  removed,  to  show  the  general  arrangement  of  the  roots  of  the 
teeth  in  situ,  and  the  shapes,  sizes  and  positions  of  their  pulp  cavities  and  root  canals. 


■■ 

i 

^^ 

[■ 

H^^i 

r 

^ 

^■^H 

^m  f^^Mii 

^^ 

^^^H^l 

a» 

1 

I^^^^H 

1      ^          flH 

• 

^^^^^^^1 

ix:'  wm 

'    -r 

^^^1 

r  »■>«  •  ^^H 

^^^^^H 

'' ""  ^1 

» 

^^H 

"f       JHaj 

.:      ^ 

1 

m 

■i 

If 

ifll 

A  B 

Fig.  20. — Horizontal  sections  through  the  alveolar  process  of  the  right  maxilla  of 
man  with  the  permanent  teeth  m  situ  at  (A)  the  gingival  margins,  at  (B)  the  root  por- 
tions, showing  the  shapes,  sizes  and  positions  of  the  pulp  cavities  and  root  canals. 


DESCRIPTIVE  GROSS  ANATOMY 


53 


A  B 

Fig.  21. — Horizontal  sections  through  the  alveolar  process  of  right  half  of  mandible 
of  man  with  the  teeth  in  situ  at  {A)  the  gingival  margins,  at  {B)  the  root  portions,  show- 
ing the  shapes,  sizes  and  positions  of  the  pulp  cavities  and  root  canals. 


Fig.  22. — The  occlusal  surfaces  of  the  permanent  teeth  in  situ.  The  dental  arch  is 
elliptical  in  shape  in  the  maxilla,  and  parabolic  in  the  mandible — a  condition  which 
obtains  in  70  per  cent,  of  cases. 


54  ANATOMY  OF  THE  TEETH  OF  MAN 

Length,  16  mm.;  width,  10  mm. 

Identification. — ^Typical  specimens  may  be  identified  as  in  the  case  of 
the  second  molar,  but  it  most  frequently  happens  that  it  is  impossible 
to  determine  to  which  side  of  the  mouth  the  tooth  belongs. 

Calcification  commences  between  the  eighth  and  ninth  year  and 
continues  until  the  eighteenth  to  the  twentieth  year.  Eruption  takes 
place  during  any  period  between  the  twentieth  and  twenty-fifth  years. 

Occlusion. — The  mesial  cusps  occlude  with  the  ridges  of  the  distal 
cusps  of  the  maxillary  second  molar  and  the  remainder  of  its  morsal 
surface  with  the  anterior  half  of  the  maxillary  third  molar. 

B.  The  Deciduous  Series. — It  is  unnecessary,  in  the  author's  judg- 
ment, to  describe  in  detail  in  this  article  the  anatomy  of  the  deciduous 
teeth.  A  few  observations,  however,  are  desirable  to  complete  what 
has  already  been  written  about  the  human  dentition. 

Ten  in  number  in  each  jaw,  the  deciduous  teeth  represent  on  a  smaller 
scale  somewhat  closely  the  main  architectural  features  of  the  permanent 
dentition.  They  differ  in  the  following  particulars:  their  general 
smallness;  their  rounded,  short  coronal  surfaces;  their  great  disparity 
in  size  with  one  another,  particularly  in  case  of  the  second  incisor  and 
second  molar;  the  universal  simplicity  of  their  coronal  patterns,  and 
unusually  constricted  necks,  due,  not  to  an  elevation  of  the  enamel  but 
to  a  curious  outward  bending  of  the  dentin  beneath. 

The  incisors  are  remarkable  in  that  their  labial  and  lingual  surfaces 
are  broader  from  side  to  side  than  from  above  downward,  those  of  the 
first  incisor  being  nearly  twice  the  width  of  the  other  two.  This  is 
particularly  noticeable  in  the  maxillary  arch.  The  outermost  incisors 
are  very  conical  in  shape.  The  canines  have  broader  crowns  than  the 
incisors.  The  roots  of  the  maxillary  teeth  are  extremely  long,  measur- 
ing nearly  twice  the  length  of  those  of  the  first  incisors.  The  first 
molars  may  frequently  be  mistaken  for  a  small  first  premolar.  All 
molars  possess  five  surfaces  which  correspond  in  name  with  those  of  the 
permanent  series.  The  crowns  usually  are  smaller  than  those  of  the 
second  molars,  but  may  on  occasion  be  larger.  Each  possesses  one 
large  inner  cusp  and  the  three  small  tubercles,  or  two  cusps  arranged 
as  a  buccal  ridge.  The  central  sulcus  is  shallow  and  may  bifurcate 
toward  the  outer  side.  Its  three  roots  are  smaller  than  in  the  second 
molar  and  widely  divergent. 

The  crowns  of  the  second  molars  possess  four  well-marked  cusps,  of 
which  the  largest  is  either  the  antero-internal  or  the  antero-external, 
the  oblique  ridge  being  well  developed  and  running  in  the  same  direc- 
tion as  in  the  permanent  teeth.  The  mandibular  second  molar  has 
five   cusps,  three  on  the  buccal  and  two  on  the  lingual  side,  the 


RELATIONSHIPS 


55 


smallest  usually  being  the  postero-buccal.     The  two  roots  are  short; 
widely  separated,  fairly  straight  and  laterally  flattened. 

The  teeth  vary  in  size^^  from  3.8  mm.  in  the  mandibular  first  incisor 
to  8.5  mm.  in  the  second  maxillary  molar. 


Fig.  23. — The  occlusal  surfaces  of  the  deciduous  teeth  in  situ. 

Calcification  occurs  approximately  as  follows :  The  first  and  second 
incisors  about  the  fourth  month  of  intra-uterine  life;  the  canine  and 
first  molar  about  the  fifth,  and  the  second  molar  about  the  fifth  to  the 
sixth  month.  At  birth  calcification  has  proceeded  to  the  extent  of 
the  formation  of  half  the  crown  of  the  first  incisor,  one-third  of  that 
of  the  second  incisor,  one-sixth  of  that  of  the  canine,  the  upper  part 
of  that  of  the  first  molar  and  the  cusps  of  the  second  molar.  They 
erupt  in  the  following  order:  first  incisor,  second  incisor,  first  molar, 
canine  and  second  molar  and  at  the  following  approximate  dates  after 
birth :  first  incisor  from  the  sixth  to  tenth  month,  second  incisor  from 
the  eighth  to  twentieth  month,  canine  fifteenth  to  the  thirty-third 
month,  first  molar  twelfth  to  the  twenty-sixth  month  and  second  molar 
twenty-eighth  to  the  thirtieth  month. 


VI.     RELATIONSHIPS. 

The  Dental  Arches. — In  shape  the  upper  is  elliptical,  the  lower 
assuming  a  parabolic  curve.     The  maxillary  teeth  in  normal  occlusion 


56 


ANATOMY  OF  THE  TEETH  OF  MAN 


slightly  overlap  the  mandibular  teeth.    The  curve  of  von  Spee,  pro- 
duced by  a  sHght  concavity  in  the  plane  of  the  occlusal  surfaces  of 


Fig.  24. — Semi-elliptical  maxillary  and  mandibular  dental  arches — a  condition  which 
obtains  in  20  per  cent,  of  cases. 


Fig.  25. — The  divergent  arch — a  condition  which  obtains  in  6  per  cent,  of  cases. 


RELATIONSHIPS 


57 


the  mandibular  teeth  and  a  corresponding  convexity  in  that  in  the 
maxillary  organs,  is  not  always  present;  it  is  probable  that  the 
normal  arrangement  of  the  parts  is  for  both  occlusal  surfaces  to  lie  in 
a  horizontal  plane. 

The  Vascular  System. — ^The  vascular  system  is  derived  from  the  in- 
ternal maxillary  artery.  The  anterior  dental  branch  of  the  infra- 
orbital division  of  the  third  or  ultimate  stage  supplies  the  maxillary 
incisors  and  canines,  the  posterior  dental  branch  the  premolars  and 
molars. 


1 

■p 

1 

|H:^' 

i^^^H^H 

5 

1  '      I^^^^^E 

^ 

HJI^HJHy    * 

Phi 

■HHJJI^^^HhK^  >« 

Fig.  26. — The  hyperbolic  arch — a  condition  which  obtains  in  4  per  cent,  of  cases. 

In  the  lower  jaw  the  mandibular  or  inferior  dental  artery  supplies  all 
the  teeth,  a  special  branch — the  incisive — passing  directly  to  the 
incisors  and  canines. 

The  Nervous  System. — ^The  trigeminal  or  trifacial  nerve — the  largest 
of  the  cranial  nerves,  sensory  in  its  upper  two  divisions  and  sensory 
and  motor  in  its  lower  third  division — endows  the  teeth  with  sensation. 
The  antero-suyerior  dental  nerve  is  distributed  to  the  maxillary  incisors 
and  canines,  the  middle  dental  to  the  premolars  and  the  posterior 
dental  to  the  molars. 

The  mandibular  or  inferior  dental  nerve  is  in  relation  with  the  molars, 
premolars  and  canines  in  its  posterior  part,  while  anteriorly  it  transmits 
an  incisive  branch  to  the  incisors. 


58  ANATOMY  OF  THE  TEETH  OF  MAN 

The  Lymphatic  System. — There  is  no  direct  connection  between  the 
pulps  of  the  teeth  and  the  lymph  nodes  of  face  and  neck,  but  the 
afferent  channels  and  vessels  of  the  gingival  tissues,  in  common  with 
those  of  the  cheeks,  lips  and  anterior  part  of  the  tongue,  communi- 
cate with  four  or  five  submaxillary  nodes  found  in  the  submaxillary 
triangle  on  the  surface  of  the  submaxillary  gland.  They  all  discharge 
their  streams  into  the  superficial  and  deep  cervical  nodes  which 
accompany  the  external  and  internal  jugular  veins  respectively. 

BIBLIOGRAPHY. 

1.  Albrecht:     "Bec-de-lifevre,"  Societe  d'Anthropologie,  Bruxelles,  1882. 

2.  Black,  G.  V.:     "Descriptive  Anatomy  of  the  Human  Teeth,"  1902. 

3.  Black,  G.  V.:     "A  Work  on  Operative  Dentistry,"  1908,  vol.  i. 

4.  5,  6  and  7.  Bland-Sutton:     "Tumors,  Iryiocent  and  Malignant,"  1906. 

8.  Bolk:     "Die  Ontogenie  der  Primatenzahne  (Odontolog.  Studien  L),  1913. 

9.  Broomell  and  Fischelis:  "Anatomy  and  Histology  of  the  Mouth  and  Teeth," 
1914. 

10.  Colyer,  J.  F.:     "John  Hunter  and  Odontology,"  1913. 

11.  Cope:  "TheTritubercular  Molar  in  Human  Dentition."  Journal  of  Morphology, 
1888. 

12.  Cryer:     "The  Internal  Anatomy  of  the  Face,"  1916. 

13.  Dolamore:  "The  Relation  of  the  Deciduous  to  the  Permanent  Dentition." 
Royal  Dental  Hospital  Gazette,  1908. 

14.  Forsyth  Major:  "On  some  Miocene  Squirrels,  with  Remarks  on  the  Dentition 
and  Calcification  of  the  Sciurinse."     Proc.  Zoo].  Soc,  London,  1893. 

15.  Gray:     "Anatomy:  Descriptive  and  Applied,"  edited  by  E.  A.  Spitzka,  1913. 

16.  17.  Hopewell-Smith:  "The  Normal  and  Histological  Pathology  of  the  Mouth," 
1918. 

18.  Hopewell-Smith:     "An  Introduction  to  Dental  Anatomy  and  Physiology,"  1913. 

19.  James,  W.  W.  and  Pitts,  A.  T.:  "Some  Notes  on  the  Dates  of  Eruption  in  Four 
Thousand  Eight  Hundred  and  Fifty  Children,  Aged  Under  Twelve,"  Proc.  Roy.  Soc. 
Med.,  1912. 

20.  Kukenthal:     "Zur  Dentitionfrage,"  Anatom.  Anzeiger,  1895. 

21.  Leche:     Morph.  Jahrbuch,  1892.     Biblio-theca  Zoologica,  1895. 

22.  Marett  Tims:  "Evolution  of  the  Teeth  in  the  Mammalia."  Jour.  Anat.  and 
Phys.,  1903. 

23.  Osborn:  "Evolution  of  the  Mammalian  Molars  to  and  from  the  Tritubercular 
Type."    Amer.  Naturalist,  1888.  . 

24.  Piersol:     "Human  Anatomy,"  1918. 

25.  Rose :  ' '  Ueber  die  Enstehung  und  Formabanderungen  der  Menschlichen  Molar  en. 
Anat.  Anzeiger,  1892. 

26.  Tomes,  C.  S.:     "A  Manual  of  Dental  Anatomy,"  seventh  edit.,  1914. 

27.  Virchow:  "Retention,  Heterotypie  und  Ueberzahl  von  Zahnen."  Verhand.  d. 
Berliner  anthrop.  Gesellschaft,  1886. 


CHAPTER   II. 

DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  OPERATIVE 

DENTISTRY.^ 

By  FREDERICK  B.  NOYES,  B.A.,  D.D.S. 

In  the  fifteen  years  or  more  that  have  elapsed  since  this  chapter  was 
prepared  for  the  third  edition  of  this  work,  there  have  been  important 
additions  to  our  knowledge  of  the  structure  of  the  teeth  and  their 
supporting  tissues.  But  more  important  even  than  these  additions 
and  changes  in  our  knowledge  of  the  facts  are  the  development  in  the 
dental  profession  and  the  recognition  of  the  relation  of  the  mouth 
conditions  to  general  systemic  conditions  and  the  health  of  the  indi- 
vidual. This  development  has  changed  the  interest  in  dental  histology 
from  one  field  to  another. 

When  the  chapter  was  first  written  dental  histology  was  being 
studied  chiefly  in  its  relation  to  the  technical  procedures  of  operative 
dentistry  and  we  may  say  with  fairness  that  the  study  of  the  structure 
of  the  enamel  with  reference  to  dental  caries  and  the  preparation  of 
cavities  was  its  most  important  phase.  The  study  of  the  microscopic 
structure  of  the  enamel  of  the  tooth  crown  greatly- improved  the  pre- 
paration of  cavities,  increased  facility  and  rapidity  of  operation  and  also 
improved  the  resulting  filling  operations.  The  facts  are  just  as  impor- 
tant as  ever  but  to  a  great  extent  they  have  already  made  their  imprint 
upon  dental  practice. 

Today  the  most  important  question  before  the  dental  profession, 
and  the  one  in  which  the  medical  profession  is  most  interested,  is  the 
fate  of  the  pulpless  tooth  and  the  relation  of  pathologic  condition  of 
the  supporting  tissues  to  the  health  of  the  organism  as  a  whole.  Dental 
histology  must  be  studied  from  this  point  of  view,  and  when  the  facts, 
so  far  as  they  are  known,  are  reviewed  from  this  standpoint,  om-  knowl- 
edge is  found  to  be  deplorably  inadequate  and  defective.  The  rational 
solution  of  the  relation  of  the  pulpless  tooth  to  the  human  organism 
cannot  be  reached  until  our  knowledge  of  structural  facts  has  been 
greatly  extended.     It  is  important,  however,  to  review  the  facts  as 

1  In  the  preparation  of  this  material  I  am  indebted  to  Dr.  G.  V.  Black  for  the  use  of 
his  large  and  valuable  collection  of  microscopic  slides,  and  for  much  advice  and  many 
suggestions. 

(59) 


60      DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

they  are  now  known  with  reference  to  these  problems.  They  are  not 
new  problems,  but  the  focus  is  now  centered  upon  them. 

From  the  standpoint  of  comparative  anatomy,  the  teeth  are  found 
to  be  not  a  part  of  the  osseous  system,  but  appendages  of  the  skin, 
and  are  to  be  compared  with  such  structures  in  the  body  as  the  nails 
and  the  hair.  The  teeth  are  a  part  of  the  exo-skeleton,  and  their 
relation  to  the  bones  of  the  endo-skeleton  is  entirely  secondary,  for 
the  purpose  of  strength,  the  bone  growing  up  around  the  tooth  to 
support  it. 

If  we  examine  the  skin, of  such  an  animal  as  the  shark,  we  find  the 
entire  surface  covered  with  small  calcified  bodies  which  are  really 
small,  simple,  cone-shaped  teeth.    The  mouth  cavity  is  to  be  regarded, 


Fig.  27. — Shark's  skull  (Lamna  cornubica) ,  showing  succession  of  teeth. 

when  viewed  in  the  light  of  its  development,  as  a  part  of  the  outside 
surface  of  the  body  which  has  been  enclosed  by  the  development  of 
the  neighboring  parts,  and  the  dermal  scales  or  rudimentary  teeth 
which  were  found  in  the  skin  covering  the  arches  which  form  the  jaws 
have  undergone  special  development  for  the  purposes  of  seizing  and 
masticating  the  food.  In  the  simplest  forms  there  is  only  a  develop- 
ment in  size  and  shape  of  these  scales,  and  they  are  supported  only  by 
the  connective  tissue  which  underlies  the  skin.  These  teeth  are  easily 
torn  off  in  the  attempt  to  hold  a  resisting  prey,  and,  as  in  the  shark, 
they  are  constantly  being  replaced  by  new  ones  (Fig.  27).  In  the  more 
highly  developed  forms  there  is  a  growth  of  the  bone  of  the  arch 
forming  the  jaw  upward  around  the  bases  of  these  scale-like  teeth,  to 
support  them  more  firmly  and  render  them  more  useful. 


DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY       61 

If  we  compare  the  structure  of  the  hair  with  that  of  the  tooth,  we 
find  in  the  case  of  the  hair  a  horny  structure  formed  by  epithehal  cells 
resting  upon  a  papilla  of  connective  tissue;  in  the  case  of  the  tooth,  a 
calcified  structure  formed  by  epithelial  cells  resting  upon  a  papilla  of 
connective  tissue  which  is  also  partially  calcified. 

The  relation  of  the  bones  of  the  jaws  to  the  teeth  is  entirely  a 
secondary  and  transient  one.  The  bone  grows  up  around  the  roots  of 
the  teeth  to  support  them,  and  is  destroyed  and  removed  with  the  loss 
of  the  teeth  or  the  cessation  of  their  function.    In  this  way  the  develop- 


y^   >4i^ 


Fig.  2S. — Changes  in  the  mandible  with  age ;  buccal  and  lingual  view. 

ment  of  the  alveolar  process  takes  place  around  the  temporary  teeth; 
all  of  this  bone  surrounding  their  roots  is  absorbed  and  removed  with 
the  loss  of  the  temporary  dentition,  and  a  new  alveolar  process  grows 
up  around  the  roots  of  the  permanent  teeth  as  they  are  formed.  This 
development  of  bone  around  the  roots  of  the  teeth  leads  to  the  changes 
in  the  shape  of  the  body  of  the  lower  jaw,  increasing  the  thickness  above 
the  mental  foramen  and  the  inferior  dtental  canal.  When  the  teeth  are 
finally  lost  this  bone  is  again  removed  and  the  body  of  the  jaw  reduced 
in  thickness  from  above  downward  (Fig.  28).  These  phenomena  are  of 
importance  in  their  bearing  upon  the  causes  and  treatment  of  diseased 


62     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


Fig.  29. ^Ground  section  of  a  canine:  E,  enamel;  Cm,  cementum;  D,  dentin;  Pc,  pulp 
chamber-  De,  dento-enamel  junction;  Ed,  enamel  defect;  G,  junction  of  enamel  and 
cementum  at  the  gingival  line;  Gt,  granular  layer  of  Tomes.  (Reduced  from  photo-micro- 
graph made  in  three  sections.) 


ENAMEL  63 

conditions  of  the  teeth,  particularly  those  which  involve  the  supporting 
tissues. 

Dental  Tissues. — ^The  human  teeth  are  made  up  of  four  tissues 
(Fig.  29). 

1.  The  enamel  covers  the  exposed  portion  of  the  tooth,  or  crown, 
and  gives  the  detail  of  crown  form.  Its  function  is  to  protect  the  tooth 
against  the  wear  of  friction. 

2.  The  dentin  forms  the  mass  of  the  tooth  and  determines  its  class 
form,  the  number  of  cusps  and  the  number  of  roots  being  indicated 
by  the  dentin  form. 

3.  Cementum  covers  the  dentin  beyond  the  border  of  the  enamel, 
overlapping  it  slightly  at  the  gingival  line  and  forming  the  surface 
of  the  root.  Its  function  is  to  furnish  the  attachment  of  the  fibers 
of  the  peridental  membrane,  which  fasten  the  tooth  to  the  bone. 

4.  The  pulp  or  soft  tissue  filling  the  central  cavity  in  the  dentin  is 
the  remains  of  the  formative  organ  which  has  given  rise  to  the  dentin. 
Its  functions  are  the  formation  of  dentin  and  a  sensory  function. 

In  describing  the  structure  of  the  teeth  and  the  arrangement  of  the 
structural  elements  of  the  tissues,  directions  are  described  with  refer- 
ence to  three  planes: 

The  mesio-disto-axial  plane,  a  plane  passing  through  the  center  of 
the  crown  from  mesial  to  distal  and  parallel  with  the  long  axis  of  the 
tooth. 

The  bucco-linguo-axial  plane,  a  plane  passing  through  the  center  of 
the  crown  from  buccal  to  lingual  and  parallel  with  the  long  axis  of  the 
tooth. 

The  horizontal  plane,  at  right  angles  to  the  axial  planes. 

The  Supporting  Tissues. — The  human  teeth  are  supported  on  the 
maxillary  bones,  their  alveolar  processes  growing  up  around  the  roots 
of  the  teeth,  so  that  the  roots  fit  into  the  holes  in  the  bone.  The 
calcified  structures  of  the  tooth  and  bone  are  not,  however,  united, 
but  the  roots  are  surrounded  by  a  fibrous  membrane,  the  peridental 
membrane,  or  pericementum,  which  fastens  the  tooth  to  the  bone. 

ENAMEL. 

The  enamel  differs  from  all  other  calcified  tissues  in  the  nature  of  the 
structural  elements  of  which  this  tissue  is  made  up,  in  the  degree  of 
calcification,  and  in  origin,  being  the  only  calcified  tissue  derived  from 
the  epiblast. 

The  enamel  is  formed  from  an  epithelial  organ  derived  from  the 
epithelium  of  the  mouth  cavity  and  indirectly  from  the  epiblastic 
germ  layer,  while  all  other  calcified  tissues  are  products  of  the  meso- 


64     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

blast.  In  the  case  of  bone  and  dentin,  the  formative  tissue  is  persistent. 
It  is  possible  in  the  bone  at  least,  therefore,  to  have  degenerative  and 
regenerative  changes,  or  the  removal  of  part  of  the  calcium  salts  and 
their  replacement  through  the  agency  of  the  formative  tissue;  while 
in  the  enamel  no  such  regenerative  change  is  possible,  as  the  formative 
tissue  disappeared  when  the  tissue  was  completed  and  before  the 
eruption  of  the  tooth. 

The  enamel  is  the  hardest  of  human  tissues.  Chemically  it  is  com- 
posed of  the  phosphates  and  carbonates  of  calcium  and  magnesium 
and  a  very  small  amount  of  the  fluorids,  water,  also  a  very  small 
amount  of  organic  matter,  if  any."^  The  enamel  in  the  natural  con- 
dition, bathed  in  the  fluids  of  the  mouth,  contains  a  considerable 
amount  of  water.  If  dried  at  a  little  above  the  boiling-point  of  water, 
it  gives  up  part  of  it  and  shrinks  considerably,  so  as  to  crack  in  fine 
checks.  If  heated  almost  to  redness,  it  suddenly  gives  off  from  3  to  5 
per  cent,  (of  the  dry  weight)  of  water  with  almost  explosive  violence. 
These  facts  were  demonstrated  some  years  ago  by  Charles  Tomes,^ 
and  account  for  most  of  what  was  formerly  recorded  as  organic  matter 
in  old  analyses. 

If  we  observe  under  the  microscope  the  action  of  acids  upon  thin 
sections  of  enamel,  when  the  inorganic  salts  are  entirely  removed,  the 
structure  of  the  tissue  vanishes,  there  being  no  trace  of  organic  matrix 
left  as  in  the  case  of  bone  or  dentin.  In  the  growth  of  bone  and  dentin 
the  formative  tissue  produces  first  an  organic  matrix  in  the  form  of  the 
tissue,  and  into  this  inorganic  salts  are  deposited,  combining  with  the 
organic  substances  of  the  matrix.  This  union  is  comparatively  weak, 
however,  for  by  the  action  of  acids  the  combination  is  broken  up  and 
the  inorganic  salts  are  dissolved;  or  by  heat  the  organic  matter  is 
removed,  and  in  either  case  the  form  of  the  tissue  will  be  maintained. 

In  the  case  of  the  enamel,  the  formative  organ  produces  organic 
substances  containing  inorganic  salts,  and  the  substances  are  arranged 
in  the  form  of  the  tissue  after  the  manner  of  a  matrix;  but  finally, 
under  the  action  of  the  formative  organ  all  of  the  organic  matter  is 
removed  and  substituted  by  inorganic  salts,  whatever  organic  matter 
is  found  in  the  fully  formed  tissue  being  the  result  of  imperfect  exe- 
cution of  the  plan. 

1  von  Bibra  gives  the  following  analysis  of  enamel: 

Calcium  phosphate  and  fluorid 89.82 

Calcium  carbonate 4.37 

Magnesium  phosphate 1 .  34 

Other  salts 0.38 

Cartilage 3.3i& 

Fat 0.20 

Total  organic 3.59 

Total  inorganic 96.41 

2  Journal  of  Physiology,  1896.  .  . 


ENAMEL 


65 


The  enamel  is  composed  of  two  structural  elements,  the  enamel 
rods,  or  prisms,  sometimes  called  enamel  fibers,  and  the  inter  prismatic 
or  cementing  substance,  both  of  which  are  calcified.  It  is  to  the  arrange- 
ment of  these  structural  elements  that  the  characteristics  of  the  tissue 
with  which  we  are  most  concerned  in  operative  procedures  are  due. 

While  both  the  prisms  and  interprismatic  substances  of  the  enamel 
are  calcified,  or,  better,  composed  of  inorganic  salts,  the  two  substances 
— that  is,  the  substance  of  the  rods  and  the  substance  between  the 
rods — show  markedly  different  properties  both  chemical  and  physical. 
If  treated  with  acid,  the  interprismatic  substance  is  acted  upon  more 
rapidly  than  the  rods,  so  that  the  latter  become  more  conspicuous. 


Isolated  enamel  rods.     (About  1000  X.) 


By  this  means  sections  of  the  enamel  may  be  etched  to  render  it  easier 
to  study  the  direction  and  arrangement  of  the  rods.  If  the  action  of 
the  acid  is  carried  far  enough,  the  rods  will  fall  apart  before  they  are 
themselves  entirely  dissolved.  Fig.  30  is  from  the  debris  in  a  carious 
cavity,  and  shows  rods  isolated  by  the  action  of  the  acids  of  caries. 

The  interprismatic  substance  is  not  as  strong  as  the  rods,  so  that  in 
splitting  or  breaking  the  enamel  the  tissue  separates  on  the  lines  of  the 
cementing  substance,  occasionally  breaking  across  a  few  rods  but 
following  their  general  direction,  the  lines  running  between  rods,  not 
at  their  centers. 

In  cleaving  the  enamel  the  chisel  does  not  enter  the  tissue  separating 
rod  from  rod,  but  the  edge  engages  with  the  surface,  and  the  force 
5 


66     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

applied  at  an  acute  angle  with  the  direction  of  the  rods  fractures  the 
tissue  in  the  lines  of  least  resistance.  If  the  edge  be  keenly  sharp,  it 
will  enter  the  tissue  slightly,  and  then  the  bevel  acts  as  a  wedge  in 
addition  to  the  force  applied  to  the  shaft  of  the  instrument;  but  if 
the  edge  be  dull,  it  will  rest  across  the  ends  of  many  rods,  will  not 
engage  with  the  surface,  and  the  force  applied  will  break  and  crumble 
the  tissue  but  will  not  cleave  it. 

The  enamel  rods,  or  prisms,  are  long,  slender  prismatic  rods  or 
fibers,  five-  or  six-sided,  pointed  at  both  ends  and  alternately  expanded 
and  constricted  throughout  their  length.  They  are  from  3.4  to  4.5 
microns^  in  diameter,,  some  of  them  apparently  reaching  the  entire 
distance  from  the  siu-face  of  the  dentin  to  the  surface  of  the  enamel; 
but  as  the  diameter  of  the  rods  is  the  same  at  their  outer  and  inner 
ends,  and  as  the  crown  surface  is  much  greater  than  the  surface  of 
dentin  covered  by  enamel,  there  are  many  rods  which  do  not  extend 
through  the  entire  thickness.  These  short  rods  end  in  tapering  points 
between  the  converging  rods  which  extend  the  entire  distance.  To 
express  this  in  terms  of  development:  as  the  formation  of  enamel 
begins  at  the  surface  of  the  dentin,  the  increasing  area  of  cro^^Ti  surface 
requires  more  ameloblasts,  and  as  new  ameloblasts  take  their  place  in 
the  layer,  the  formation  of  new  enamel  rods  begins  between  the  rods 
which  were  previously  forming.  These  short  rods  are  most  numerous 
over  the  marginal  ridges  and  at  the  points  of  the  cusps,  and  will  be 
considered  more  fully  in  connection  with  those  positions. 

In  ground  sections  cut  at  right  angles  to  the  direction  of  the  rods,^ 
the  tissue  has  the  appearance  of  a  mosaic  floor,  the  outline  of  the 
rods  being  more  distinct  if  they  have  been  marked  out  by  treating  the 
section  slightly  with  acid  (Fig.  31).  In  longitudinal  sections  (Fig.  32) 
the  sides  of  the  rods  are  not  smooth  and  even  like  the  sides  of  a  lead 
pencil,  but  are  alternately  expanded  and  constricted.  They  are  well 
illustrated  by  taking  balls  of  soft  clay  and  sticking  them  together 
one  above  another  to  form  a  rod,  then  putting  a  number  of  rods  to- 
gether so  that  by  mutual  pressure  they  take  hexagonal  forms.  This 
illustrates  also  the  manner  of  gro\\i;h  of  the  tissue  in  formation.  The 
expansions  and  constrictions  can  be  seen  in  rods  that  have  been  scraped 
from  a  cleaved  surface  of  enamel,  but  better  by  isolating  rods  by  the 
slight  action  of  dilute  acid  (Fig.  33). 

In  the  construction  of  the  tissue  the  rods  are  so  arranged  that  the 
expansions  of  one  rod  come  opposite  to  the  expansions  in  the  adjoining 

1  A  micron  is  the  unit  of  microscopic  measurement,  and  is  equal  to  one-thousandth 
of  a  millimeter. 

2  In  describing  the  direction  of  enamel  rods  they  are  always  considered  as  extending 
from  the  dentin  to  the  surface,  and  the  angle  is  formed  at  the  surface  of  the  dentin 
with  the  locating  plane,  either  horizontal  or  axial. 


ENAMEL 


67 


rods,  and  do  not  interlock  with  their  constructions.  This  arrangement 
leaves  alternately  a  greater  and  a  less  amount  of  cementing  substance 
between  them. 


Fig.  31. — Transverse  section  of  enamel  rods.      (About  8U   X.) 


Fig.  32. — Enamel  rods  in  thin  etched  section.     (About  800  X.) 


When  observed  under  the  microscope,  the  enamel  rods  show  a 
characteristic  appearance  of  light  and  dark  lines  running  across  them. 
These  markings  are  similar  to  the  striations  of  voluntary  muscle  fibers, 


68     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

and  are  described  as  the  striation  of  the  enamel.  It  is  seen  not  only  in 
isolated  rods,  but  also  in  sections  ground  in  their  direction  (Fig.  34). 
This  appearance  of  striation  in  the  enamel  is  caused  by  the  alternate 


Fig.  33. — Enamel  rods  isolated  by  scraping.     (About  800  X.) 


Fig.  34. — Enamel  showing  striation.     (About  1000  X.) 


expansions  and  constrictions  of  the  rods  refracting  the  light  like  a  lens. 
In  sections  the  expansions  in  adjoining  rods  are  opposite  to  each 
other,  the  difference  in  the  refracting  power  of  the  prismatic  and  inter- 
prismatic  substances  producing  the  same  effect. 


ENAMEL  69 

The  appearance  of  striation  is  the  record  in  the  fully  formed  tissue 
of  the  manner  of  growth,  each  dark  stripe,  or  expansion,  in  a  rod 
representing  a  globule  of  partially  calcified  material.  The  ameloblasts 
build  up  the  rods  by  the  addition  of  globule  after  globule,  surrounding 
them  with  a  cementing  substance  and  completing  the  calcification  of 
both.  In  this  sense  the  striation  of  the  enamel  may  be  said  to  record 
the  growth  of  the  individual  rods. 

While  the  enamel  is  a  very  hard  substance  when  its  structure  is 
complete  and  perfect,  its  most  striking  physical  characteristic  is  a 
tendency  to  split  or  crack  in  the  direction  of  its  structura,l  elements 
when  a  break  has  been  made  in  the  tissue.  While  it  is  difficult  to  cut 
across  the  rods  or  make  an  opening  on  a  perfect  surface,  if  a  break  has 


Fig.  35. — Enamel  showing  direction  of  cleavage.      (About  70  X.) 

been  established  it  is  comparatively  easy  to  split  off  the  tissue  from  the 
sides  of  the  opening  when  the  rods  lie  parallel  with  each  other.  Fig.  35 
shows  a  field  of  enamel  illustrating  the  way  in  which  the  tissue  splits 
or  cleaves  in  the  direction  of  the  rods. 

Upon  the  axial  siu-faces  the  enamel  rods  are  usually  straight  and 
parallel  with  each  other,  except  where  there  has  been  some  flaw  or 
disturbance  in  development;  but  upon  the  occlusal  surface,  although 
sometimes  straight,  they  are  ver}-  often  much  twisted  and  wound  round 
each  other,  especially  at  their  inner  ends.  This  difference  in  the  arrange- 
ment of  the  rods  causes  the  greatest  difference  in  the  feeling  of  the  tissue 
under  cutting  instruments.  Such  a  specimen  of  enamel  as  sho\\Ti  in 
Fig.  36  can  be  cut  away  easily,  the  tissue  breaking  through  to  the 
dentin  and  splitting  oft'  in  chunks;  while  a  specimen  like  Fig.  37  will 


70    DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


Fig.  36. — Straight  enamel  rods.     (About  80  X.) 


_^_^...^ 


Fig.  37. — Gnarled  enamel.     (About  80  X.) 


ENAMEL 


71 


not  cleave  if  supported  upon  sound  dentin.  If  the  outer  ends  of  the 
rods  are  straight,  they  will  split  part  way  to  the  dentin  (Fig.  38) ;  but 
where  they  begin  to  twist  round  each  other  they  will  break  across  the 
rods.  If  the  dentin  is  removed  from  under  such  enamel,  it  will  break 
in  an  irregular  way  through  the  gnarled  portion. 


Fig.  38. — Gnarled  enamel.     (About  50  X .) 


From  a  study  of  the  arrangement  of  the  enamel  rods  in  the  formation 
of  the  crown  it  is  apparent  that  the  plan  is  such  as  to  give  the  greatest 
strength  to  the  perfect  structure,  and  may  be  likened  to  an  arch.  At 
the  gingival  border  the  rods  are  short  and  are  inclined  apically  6  to  10 
centigrades^  (20°  to  35°)  from  the  horizontal  plane.    These  short  rods 


1  In  the  centigrade  division  the  circle  is 
divided  into  one  hundred  parts,  each  called 
a  centigrade.  One  centigrade  is  equal  to 
3.6  degrees  of  the  astronomical  circle,  25 
centigrades  to  90  degrees,  12  centigrades 
to  45  degrees.  The  cut  gives  a  compari- 
son of  the  two  systems  of  measuring 
angles. 


2  70 


180 
Centigrade  division. 


72    DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

are  overlapped  for  a  short  distance  by  the  cementum.  This  iiidination 
grows  less  and  less,  and  at  some  place  in  the  gingival  half  of  the  middle 
third  of  the  surface  they  are  in  the  horizontal  plane.  At  this  point 
they  are  also  usually  perpendicular  to  the  surface  of  the  dentin.  Pass- 
ing from  this  point  they  become  inclined  more  and  more  occlusally 
from  the  horizontal  plane,  at  the  junction  of  the  occlusal  and  middle 
thirds  about  8  to  12  centigrades  (28°  to  40°)  in  bicuspids  and  molars, 
and  8  to  18  centigrades  (28°  to  65°)  in  incisors  and  canines.  In  the 
occlusal  third  the  inclination  increases  rapidly,  and  often  the  outer 


Fig.  39. — Diagram  of  enamel  rod  directions,  from  a  photograph  of  a  bucco-lingual  sec- 
tion of  an  upper  bicuspid. 


ends  of  the  rods  are  inclined  more  than  the  inner  ends.  Over  the  point 
of  the  cusps  and  the  crest  of  the  marginal  ridges  the  rods  reach  the 
axial  plane,  though  they  are  often  very  much  twisted  about  each  other 
in  the  inner  half  of  their  length.  This  position  does  not  always  corre- 
spond with  the  highest  point  of  the  cusp,  but  is  inclined  slightly  axially 
from  that  position,  and  corresponds  with  the  highest  point  of  the  dentin 
cusp. 

Passing  down  the  central  slope  of  the  cusp,  or  ridge,  the  rods  become 
again  inclined  away  from  the  axial  plane  toward  the  groove,  or  pit. 


ENAMEL 


73 


leaning  toward  each  other  where  the  two  plates  meet.  The  degree  of 
inclmation  of  the  rods  on  the  central  slope  of  the  cusps  depends  upon 
the  height  of  the  cusps;  the  higher  the  cusp  the  greater  the  inclination 
from  the  axial  plane.  Fig.  39,  a  diagram  from  a  photograph  of  a 
bucco-lingual  section  of  an  upper  bicuspid,  shows  the  plan  of  arrange- 
ment and  illustrates  the  arch  principle  in  the  construction. 


Fig.  40. — Stratification  of  enamel;  the  cusp  of  a  bicuspid:  De,  dento-enamel  junction; 
Ed,  enamel  defect  showing  in  the  heavy  stratification  band ;  Ig,  interglobular  spaces  in 
the  dentin.     (About  40  X.) 


In  the  study  of  longitudinal  sections  of  the  teeth,  one  of  the  most 
conspicuous  structural  features  is  the  stratification  bands  or  brown 
bands  of  Retzius.  These  bands  are  not  parallel  with  either  the  outer 
surface  of  the  enamel  or  the  dento-enamel  junction.  They  begin  at 
the  tip  of  the  dentin  cusps  and  sweep  around  in  larger  and  larger  zones. 


74     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


Fig.  41. — -Incisor  tip  showing  stratification  or  incremental  lines.    Rods  at  A  were  fully 
formed  at  the  time  the  rods  at  B  were  beginning  to  form.     (About  50  X.) 


Fig.  42. — -Enamel  showing  both  striatiou  and  stratification.     (About  80  X.) 


REQUIREMENTS  FOR  STRENGTH  IN  ENAMEL  WALLS        75 

These  stratification  bands  are  better  seen  in  comparatively  thick 
sections,  and  are  caused  by  the  varying  amount  of  pigment  deposited 
with  the  calcium  salts  in  the  development  of  the  tissue.  They  record 
the  growth  of  enamel  of  the  crown  as  a  whole,  as  each  line  was  at  one 
time  the  surface  of  the  enamel  cap.  These  stratifications,  or  better, 
incremental  lines,  are  shown  in  Fig.  40. 

At  the  time  the  rod  at  A  (Fig.  41)  was  completely  formed  the  rod 
at  B  was  just  beginning  to  form  at  its  dentinal  end.  From  this  it  would 
seem  that  any  structural  defect  due  to  imperfect  development  would 
not  follow  the  direction  of  the  enamel  rods  from  the  surface  to  the 
dentin,  but  would  follow  the  stratification  lines;  and  if  these  struc- 
tural defects  influenced  the  penetration  of  caries,  we  should  expect  to 
have  the  direction  of  penetration  modified.  Fig.  42  shows  a  structural 
defect  in  the  enamel  over  a  cusp  following  the  stratification  band,  and 
it  will  be  noticed  also  that  there  is  a  structural  defect  in  the  dentin  at  a 
corresponding  position. 

HISTOLOGICAL  REQUIREMENTS  FOR  STRENGTH  IN  ENAMEL 

WALLS. 

1.  The  enamel  must  be  supported  upon  sound  dentin. 

2.  The  rods  which  form  the  cavo-surface  angle  must  run  uninterrupt- 
edly to  the  dentin  and  be  supported  by  short  rods,  with  their  inner  ends 
resting  on  the  dentin  and  their  outer  ends  abutting  upon  the  cavity 
wall,  where  they  will  be  covered  in  by  the  filling  material. 

3.  That  the  cavo-surface  angle  be  cut  in  such  a  way  as  not  to  expose 
the  ends  of  the  rods  to  fracture  in  condensing  and  filling  material 
against  them. 

In  thinking  of  the  supporting  tissues  it  has  been  too  much  the  habit 
to  think  of  the  bone  and  the  fibrous  tissues  as  separate  entities  or 
anatomically  distinct  things.  Instead  of  this  point  of  view,  the  sup- 
porting tissues  should  be  thought  of  as  a  connected  tissue  organ  of 
support,  part  of  which  is  calcified  for  the  purpose  of  rigidity.  The  bone 
of  the  alveolar  process,  the  fibrous  tissue  of  the  peridental  membrane, 
periosteum  and  septal  tissue  should  be  thought  of  as  only  parts  of  a 
whole  which  function  as  an  organ  of  support  to  the  denture,  sustaining 
the  teeth  in  their  function  and  keeping  the  epithelium  in  proper  relation 
to  the  teeth  for  the  protection  of  the  supporting  tissues  from  injury 
and  infection. 

The  first  step,  then,  in  the  preparation  of  an  enamel  wall  is  to  deter- 
mine the  direction  of  the  enamel  rods  by  cleavage  with  a  chisel  or 
hatchet.  In  Fig.  43,  No.  1  shows  an  enamel  wall  after  cleaving  the  enamel 
with  a  hatchet.    It  will  be  noticed  that  the  split  has  not  followed  the 


76     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


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REQUIREMENTS  FOR  STRENGTH  IN  ENAMEL  WALLS         77 

direction  of  the  rods  exactly,  but  has  broken  across  them,  slivering  the 
rods  as  wood  slivers  in  splitting.  This  would  cause  in  the  cut  surface 
a  whitish,  opaque  appearance.    The  plane  of  the  enamel  wall  should 


be  extended  so  as  to  form  a  small  angle  with  the  plane  of  the  dental 
wall,  by  shaving  the  surface  with  a  very  sharp  hand  instrument.  No. 
2  shows  the  same  wall  after  it  has  been  extended  somew^hat;  but  it 


78     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

will  be  seen  that  it  has  not  been  extended  enough,  for  the  rods  forming 
the  surface  at  A  do  not  reach  the  dentin,  but  run  out  at  B  on  the 
cavity  wall,  and  that  piece  would  chip  out  in  packing  against  it  or  if 
force  came  upon  the  surface  afterward.  The  angle  should  be  extended 
so  as  to  produce  the  plane  shown  in  No.  3;  then  the  cavo-surface  angle 
may  or  may  not  be  beveled  as  the  position  demands. 


Fig.  45. — Occlusal  fissure  in  an  upper  bicuspid,  showing  direction  of  rods.    (About  SOX.) 

With  reference  to  the  direction  of  the  enamel  rods  in  relation  to  the 
cavity,  enamel  walls  may  be  divided  into  two  classes:  (1)  those  in 
which  the  rods  are  inclined  toward  the  cavity,  characteristic  of  grooves, 
fissures,  and  pits;  and  (2)  those  in  which  the  rods  are  inclined  away 
from  the  cavity,  characteristic  of  cavities  beginning  on  smooth  axial 
surfaces.    In  the  first  it  is  easy  to  obtain  the  structural  requirements  for 


REQUIREMENTS  FOR  STRENGTH  IN  ENAMEL  WALLS         79 

a  strong  wall.  In  the  second  it  is  comparatively  difficult.  It  is  impor- 
tant to  remember  that  strength  is  measured  by  the  degree  to  which  the 
structural  requirements  are  attained. 

Grooves,  fissures,  and  pits  are  always  positions  of  weakness,  and 
when  a  cavity  approaches  a  groove  or  pit.  a  good  margin,  histologically, 
cannot  be  prepared  without  cutting  beyond  it.     Fig.  45  shows  an 


Fig.  46. — Bucco-lingiial  section  of  upper  bicuspid;  enamel  is  broken  from  grinding: 
A  to  B,  area  of  weakness  for  enamel  margins.     (About  20  X.) 


occlusal  fissure  in  a  bicuspid,  which  illustrates  the  conditions  of  struc- 
ture characteristic  of  these  positions.  The  rods  are  inclined  toward  the 
fissure,  and  between  the  bottom  of  the  fissure  and  the  dentin  are  very 
irregular.  If  a  cavity  wall  were  made  to  approach  this  fissure  from  the 
lingual  side,  so  as  to  come  to  the  dotted  line,  the  wall  would  have  to  be 
inclined  6  to  8  centigrades  (20°  to  28°)  from  the  axial  plane  toward  the 
fissure,  and  then  the  cavo-surface  angle  beveled,  when  the  conditions 


80     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

would  be  similar  to  those  in  the  wall  of  an  axial  surface  cavity,  and 
not  as  strong  as  the  location  requires.  Not  only  is  this  true,  but  it  also 
leaves  a  vulnerable  point  next  to  the  margin  of  the  filling— a  point  of 


Fig.  47. — Enamel  over  tip  of  dentin  cusp:  D,  dentin  cusp.     (About  80  X.) 

liability.  Cutting  just  beyond  the  fissure,  the  wall  may  be  left  in  the 
axial  plane  and  have  an  ideally  strong  margin,  and  the  point  of  liability 
is  removed.    To  state  the  conditions  in  general  terms,  a  strong  margin 


DENTIN  81 

is  more  easily  obtained  where  enamel  rods  are  inclined  toward  the 
cavity  than  where  they  are  inclined  away  from  the  cavity. 

The  points  of  cusps  and  the  crests  of  marginal  ridges  are  positions 
of  strength  in  the  perfect  tissue;  but  when  a  cavity  margin  approaches 
them  they  become  points  of  weakness,  because  it  is  impossible  to  sup- 
port properly  the  rods  which  form  the  margin.  Over  the  marginal 
ridges  are  many  short  rods  which  do  not  reach  the  dentin,  and  these  are 
usually  very  much  twisted  about  each  other,  so  as  to  form  the  strongest 
possible  keystone  in  the  perfect  structure.  In  preparing  a  margin  in 
such  a  position  it  is  impossible  to  have  the  rods  which  form  the  margin 
reach  the  dentin  with  their  inner  ends,  and  these  short  rods  are  sure 
to  break  in  completing  the  operation  or  to  break  out  later.  The 
arrangement  of  enamel  rods  in  such  positions  is  to  be  borne  in  mind, 
especially  when  extending  approximate  cavities  in  incisors  toward 
the  lingual  side  and  in  large  pit  cavities  in  incisors.  A  similar  condition 
is  found  over  the  points  of  the  cusps.  Fig.  46  shows  a  bucco-lingual 
section  of  an  upper  bicuspid.  It  will  be  noticed  that  the  rods  forming 
the  point  of  the  cusp  are  not  in  the  axial  plane,  and  do  not  reach  the 
tip  of  the  dentin  cusp,  but  reach  the  dentin  a  little  way  down  on  the 
outer  slope.  The  enamel  covering  the  tip  of  the  dentin  contains  many 
short  rods,  and  they  are  very  much  twisted  about  each  other,  so  that 
the  area  from  A  and  B  to  the  point  of  the  cusp  is  an  area  of  weakness 
for  the  cavity  margins.  If  the  margin  reaches  this  area,  the  cusp  must 
be  cut  away  and  the  enamel  wall  carried  out  in  the  horizontal  plane. 
Fig.  47  shows  this  area  more  highly  magnified,  and  illustrates  the 
structure.  It  will  be  noticed  that,  in  grinding,  some  of  the  short 
twisted  rods  have  broken  out  of  the  section. 


DENTIN. 

Dentin  belongs  to  the  connective-tissue  group,  and  is  made  up  of  a 
solid  organic  matrix  impregnated  with  about  72  per  cent,  of  inorganic 
salts^  and  pierced  by  minute  canals  or  tubuli,  which  radiate  from  a 
central  cavity  which  contains  the  remains  of  the  formative  organ,  or 
pulp.  The  minute  canals,  or  dentinal  tubuli,  are  occupied  in  life  by 
protoplasmic  processes  from  the  odontoblastic  cells  which  form  the 

1  von  Bibra  gives  the  following  analysis  of  dentin: 

Organic  matter 27.61 

Fat '....-..  0.40 

Calcium  phosphate  and  fluorid 66.72 

Calcium  carbonate 3.36 

Magnesium  phosphate 1 .  08 

Other  salts 0.83 

6 


82     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

outer  layer  of  the  pulp.    Dentin  contains  two  kinds  of  organic  matter, 
the  contents  of  the  tubuli  and  the  organic  basis  of  the  matrix. 

From  a  study  of  microscopic  sections  it  appears  that  the  total  volume 
of  the  dentinal  tubuli  amounts  to  approximately  one-tenth  of  the  entire 
volume  of  the  dentin.  The  contents  of  these  spaces  and  its  fate  are 
important  factors  in  the  question  of  pulpless  teeth.  Unfortunately 
very  little  is  positively  known  about  the  contents  of  the  dentinal  tubuli. 
And  there  is  a  very  great  diversity  of  opinion  among  the  authorities 
on  the  subject.  During  the  formation  of  dentin,  it  is  apparent  that 
protoplasmic  projections  of  the  odontoblasts  are  left  in  the  dentinal 
tubuli  (though  this  is  disputed  by  some  authors,  see  Hopewell-Smith) ; 
but  whether  this  condition  is  permanent  or  not  is  by  no  means  certain. 
Some  authors  (Howard  Mummery)  claim  to  have  demonstrated  nerve 
fibers  in  the  dentinal  tubuli;  at  present  the  author  feels  that  much 
work  must  be  done  on  this  subject  before  the  facts  are  clearly  estab- 
lished. In  recent  study  the  author  has  been  convinced  that  in  the 
formation  of  dentin  many  cells  are  enclosed  in  the  matrix  but  what 
their  fate  is  and  what  is  their  relation  to  the  matrix  is  not  known. 

The  dentin  matrix,  after  the  removal  of  the  calcium  salts  by  acids, 
yields  gelatin  on  boiling  and  resembles  the  matrix  of  bone,  reacting  in 
a  similar,  though  not  identical,  way  with  staining  agents.  The  por- 
tion of  the  matrix  immediately  surrounding  the  tubuli  shows  different 
chemical  characteristics  from  the  rest  of  the  matrix,  resembling  elastin, 
and  resisting  the  action  of  strong  acids  and  alkalies  after  the  rest  of  the 
tissue  has  been  destroyed.  This  portion  of  the  matrix  surrounding 
the  tubuli  and  lying  next  to  the  fibrils  is  known  as  the  sheaths  of 
Neumann. 

The  dentinal  tubuli  are  from  1.1  to  2.5  microns  in  diameter,  and 
are  separated  from  each  other  by  a  thickness  of  about  10  microns  of 
dentin  matrix.  This  is  fairly  uniform  throughout  the  dentin.  The 
character  of  the  tubuli  is  different  in  the  crown  and  root  portions. 

In  the  crown  the  tubuli  branch  little  through  most  of  their  course; 
but  in  the  outer  part,  close  to  the  enamel,  they  branch  and  anastomose 
with  each  other  quite  freely.  Fig.  48  shows  a  field  of  dentin  just 
beneath  the  enamel,  as  seen  with  a  high  power  and  shows  the  diameter 
of  the  tubuli,  their  branching,  and  the  amount  of  matrix  between  one 
tubule  and  the  next.  The  relation  of  one  tubule  to  another  is  shown 
also  in  sections  cut  at  right  angles  to  their  direction  (Fig.  49).  In 
the  crown  portion  the  tubuli  pass  from  the  pulp  chamber  to  the 
dento-enamel  jmiction  in  sweeping  curves,  so  as  to  enter  the  pulp 
chamber  at  right  angles  to  the  surface,  and  end  next  to  the  enamel 
at  right  angles  to  that  surface.  This  produces  S-  or  F-shaped  ( C ) 
curves,   which    are   known   as   the    primary   curves    of    the    tubuli. 


DENTIN 


83 


Fig.  48. — Dentin  at  dento-enamel  junction,  showing  tubuli  cut  longitudinally:  Dt, 
dertinal  tubuli;  D,  dentin  matrix.     (About  760  X.) 


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Fig.  49. — Dentin,  showing  tubuli  in  cross-seetii)n:  Dt,  dentinal   tiitnili;   D,  dentin 
matrix;  S,  shadow  of  sheaths  of  Neumann.     (About  1150  X.) 


84     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

Throughout  theu"  coiuse  the  tubuh  are  not  straight,  but  show  a  great 
many  wavy  curves,  known  as  the  secondary  ciu'ves.  These  appear 
as  waves  when  seen  in  longitudinal  sections,  but  are  really  the  effect 
of  an  open  spiral  direction,  as  is  seen  by  changing  the  focus  of  the 
microscope  in  studying  sections  cut  at  right  angles  to  the  direction  of 
the  tubuli.  The  branches  throughout  their  length  are  few  and  small 
and  are  given  oft'  at  an  acute  angle  to  the  direction  of  the  tubule;  but 
just  before  the  enamel  is  reached  the  tubuli  fork  and  branch  producing 
an  appearance  similar  to  the  delta  of  a  river.    These  branches  are  given 


Fig.  50. — -Crown  of  a  molar,  mesio-distal  section,  sho\^'ing  penetration  of  caries :  A ,  caries 
penetrating  dentin;  B,  line  of  abrasion;  P,  pulp  chamber.     (About  20  X.) 


off  from  the  tubuli  for  some  little  distance  back  from  the  enamel,  and 
they  anastomose  with  other  tubuli  very  freely.  The  branching  of  the 
tubuli  in  their  outer  portion  causes  the  spreading  of  caries.  Just 
beneath  the  enamel  the  microorganisms  growing  through  the  branches 
from  tube  to  tube,  spread  sideways  beneath  the  enamel  plates,  and 
penetrate  the  dentin  in  the  direction  of  the  tubuli.  Fig.  50  shows  the 
penetration  of  caries  in  the  dentin.  It  will  be  noticed  that  in  decay 
starting  at  the  contact  point,  there  has  been  more  spreading  under  the 
enamel  than  in  that  starting  at  the  gingival  line,  but  in  both  positions 
the  penetration  has  followed  the  direction  of  the  tubuli. 


DENTIN 


85 


In  the  root  portion  the  tubuli  pass  out  from  the  pulp  canals  at  right 
angles  to  the  long  axis  of  the  tooth  and  pass  directly  out  to  the  cemen- 
tum,  showing  only  the  secondary  curves.  Throughout  their  course 
they  give  off  a  great  many  fine  branches  passing  through  the  matrix 
in  all  directions  from  tubule  to  tubule.  These  branches  are  so  muner- 
ous  that  in  sections  which  have  been  mounted  in  such  a  way  as  to  leave 
air  in  them,  or  if  the  tubuli  have  been  filled  with  coloring  matter,  they 
give  the  impression  of  looking  through  a  hazel  bush;  or  they  may  be 


Fig.  51. — Dentin  from  the  root,  showing  tubuli  cut  longitudinally.     (About  700  X.) 


likened  to  the  fine  rootlets  of  a  plant.  These  fine  branches  are  shown 
in  Fig.  51,  and  the  character  of  the  dentin  in  the  root  portion  is  to  be 
compared  with  that  in  the  crown  portion  as  showm  in  Fig.  48.  The 
outermost  layer  of  the  dentin  next  to  the  cementum  contains  many 
small  irregular  spaces,  which  connect  with  the  dentinal  tubuli  and 
give  to  the  tissue  when  seen  with  low  powers  a  granular  appearance. 
This  layer  was  first  described  by  John  Tomes  as  the  granular  layer,  and 
has  since  been  usually  called  the  granular  layer  of  Tomes.  The  spaces 
of  the  granular  layer  are  probably  filled  by  the  enlarged  ends  of  the 


86     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


Fig.  52. — -Dento-enamel  junction.     (About  70  X.) 


> 


i'h'  }"'■/ 


¥ 


¥i3,.  53. — Interglobular  spaces  in  dentin:  Ig,  first  line  of  interglobular  spaces ;  Ig',  second 
line  of  interglobular  spaces.     (About  30  X.) 


DENTIN 


87 


dentinal  fibrils.    The  same  appearance  is  sometimes  seen  beneath  the 
enamel,  but  is  never  as  well  marked  as  next  to  the  cementum. 

In  recent  study  of  material  prepared  by  Dr.  Newton  G.  Thomas 
and  Dr.  William  S.  Skillen  the  author  has  been  convinced  that  the 
spaces  in  the  granular  layer  of  Tomes  are  formed  and  occupied  by 
cells  enclosed  in  the  formation  of  the  matrix,  but  whether  they  are 
persistent  or  not  seems  doubtful. 


Fig.  54. — -Granular  layer  of  Tomes:  L,  lacunse  of  cementum;  Gt,  granular  layer  of  Tomes; 
Ig,  interglobular  spaces.     (About  200  X.) 


The  dentin  at  the  dento-enamel  junction  seldom  presents  a  smooth 
surface,  but  the  inner  surface  of  the  enamel  plate  shows  rounded  pro- 
jections, between  w^hich  the  dentin  extends.  In  sections  this  gives 
to  the  dento-enamel  junction  a  scalloped  appearance  as  shown  in 
Fig.  52;  and  often  the  deceptive  appearance  of  the  dentinal  tubuli 
penetrating  for  a  short  distance  between  the  enamel  rods. 

In  many  specimens  made  by  grinding  dried  teeth,  large  irregular 
spaces  are  very  conspicuous  in  the  dentin.  They  usually  occur  in 
lines  or  zones  at  about  uniform  depth  from  the  surface.    These  have 


88     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

been  called  the  interglobular  spaces.  They  are  really  not  spaces  at  all, 
but  are  areas  of  imperfect  development  in  which  the  dentin  matrix 
has  not  been  classified.  The  dentinal  tubuli  pass  through  them  without 
interruption.  In  a  dried  specimen  the  organic  matrix  shrinks,  and  the 
resulting  space  becomes  filled  with  debris  of  grinding,  so  as  to  give  the 
appearance  of  black  spaces.  Fig.  53  shows  two  quite  distinct  layers  of 
interglobular  spaces,  the  second  much  more  marked  than  the  first; 
and  in  the  enamel  at  a  position  corresponding  to  the  first  is  seen  an 


Fig.  55. — Granular  layer  of  Tomes:  L,  lacunge  of  cementum;  GT,  granular  layer  of 
Tomes;  Iff,  interglobular  spaces.     (About  200  X.) 


imperfection  of  structure  marked  by  the  very  dark  stratification  band. 
This  is  shown  best  in  the  region  of  the  cusp  (Fig.  40)  from  the  same 
section.  Interglobular  spaces  in  the  root  portion  of  the  dentin  are 
shown  in  Fig.  54,  close  to  the  granular  layer  of  Tomes. 

The  formation  of  dentin  is  not  complete  at  the  period  of  eruption  of  a 
tooth,  but  continues  for  an  indefinite  period,  thickening  the  layer  of 
dentin  at  the  expense  of  the  pulp.  When  the  typical  amount  of  dentin 
has  been  formed  the  growth  ceases,  and  does  not  begin  again  unless 


PULP  89 

excited  by  some  irritation  to  the  pulp  or  the  pulp  of  some  other  tooth 
of  the  same  side,  which  leads  to  the  formation  of  a  secondary  dentin. 
Secondary  dentin  is  never  as  perfect  in  structure  as  primary  dentin; 
the  tubuli  are  smaller,  fewer,  and  much  more  irregular.  Often  in 
ground  sections  several  periods  of  formation  can  be  determined  by 
differences  in  structure,  each  deposit  becoming  successively  more  and 
more  imperfect  in  structure.      This  is  shown  in  Fig.  55. 

PULP. 

The  dental  pulp  is  the  soft  tissue  occupying  the  central  cavity  of  the 
dentin.  It  is  made  up  of  embryonal  connective  tissue  and  contains  a 
large  number  of  bloodvessels  and  nerves.  Like  all  connective  tissues, 
the  intercellular  substance  is  large  in  amount  and  the  cells  are  widely 
scattered  in  this  soft,  jelly-like  tissue,  which  contains  but  few  fibers. 
We  recognize  four  kinds  of  cells  in  the  pulp :  the  odontoblasts,  forming 
the  outer  surface  of  the  pulp  next  to  the  dentin;  and  round,  spindle- 
shaped,  and  stellate  connective-tissue  cells. 

Arrangement  of  Cells. — ^The  odontoblasts  are  tall  columnar  cells, 
sometimes  club-shaped,  and  in  older  tissues,  which  have  ceased  to  be 
functional,  sometimes  become  almost  spherical.  They  form  a  con- 
tinuous layer  over  the  entire  surface  of  the  pulp,  being  everywhere  in 
contact  with  the  dentin.  The  layer  has  been  called  the  membrana 
eboris,  or  the  "membrane  of  the  ivory." 

The  nuclei  of  the  odontoblasts  are  large  and  oval,  contain  a  large 
amount  of  chromatin,  and  are  very  different  from  the  nuclei  of  ordinary 
connective-tissue  cells. 

Three  kinds  of  processes  have  been  described  in  connection  with  the 
odontoblasts : 

1.  The  dentinal  fibril  processes  or  fibers  of  Tomes.  These  are  long, 
slender  protoplasmic  processes  projecting  from  the  dentin  end  of  the 
cell  into  a  dentinal  tubule,  and  running  through  the  tubule  to  the 
outer  surface  of  the  dentin.  Usually  there  is  but  one  fibril  extending 
from  each  odontoblast,  but  sometimes  two  can  be  seen,  extending  into 
two  tubuli.  These  fibrils  can  be  demonstrated  in  decalcified  sections 
or  by  removing  the  pulp  from  a  recently  extracted  tooth  by  cracking 
the  tooth  and  carefully  lifting  the  pulp  out  of  the  pulp  chamber,  and 
then  either  teasing  or  sectioning.  Fig.  56  shows  the  fibrils  projecting 
from  the  surface;  but  in  this  section  the  cut  was  not  in  the  direction  of 
the  long  axis  of  the  odontoblasts,  but  obliquely  through  them.  Fig.  57 
(from  a  photograph  by  Rose)  shows  the  form  of  the  odontoblasts  in  a 
young  tooth  in  which  formation  of  dentin  is  actively  progressing,  with 
the  fibrils  in  the  dentinal  tubuli. 


90     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

2.  Lateral  processes  projecting  from  the  sides  of  the  cells  and  uniting 
one  with  another  in  the  formation  of  the  layer. 


Fig.  56. — ^Odontoblasts.  The  section  cuts  obliquely  through  the  odontoblasts:  F, 
fibrils;  A?',  nuclei  of  odontoblasts;  iV',  nuclei  of  connective-tissue  cells;  W,  layer  of  Weil, 
not  well  shown.     (About  80  X.) 


Fig.  57. — Odontoblasts  and  forming  dentin:  E,  forming  enamel;   D,  forming  dentin- 
O,  odontoblasts;  Dp,  body  of  dental  papilla.     (From  photo-micrograph  by  Rose.) 


PULP  91 

3.  Piilpal  processes,  projecting  from  the  pulpal  ends  of  the  odonto- 
blasts into  the  layer  of  Weil. 

The  odontoblasts,  as  the  name  indicates,  are  the  dentin-forming 
cells.  They  superintend  the  formation  and  calcification  of  the  dentin 
matrix,  the  fibril  being  left  behind  surrounded  by  the  formed  tissue. 
Whether  the  fibrils  have  any  share  in  the  formation  and  calcification 
of  the  dentin  matrix  has  been  a  matter  of  controversy. 

One  author  claims  that  the  odontoblasts  have  no  part  in  the  for- 
mation of  dentin,  but  it  seems  incredible  that  this  view  could  be  held 
by  anyone  who  had  made  even  a  superficial  examination  of  the  tissues 
during  dentin  formation. 

The  relation  of  the  fibrils  to  the  transmission  of  sensation  is  also  a 
matter  of  dispute;  but  at  present  the  weight  of  evidence  is  that  they 
in  some  way  transmit  impressions  to  the  sensory  nerves  of  the  pulp. 

The  relation  of  the  odontoblasts  and  the  fibril  to  the  dentin  matrix 
is  of  great  importance  just  now  in  the  solution  of  the  problem  of  the 
pulpless  tooth.  It  is  important  to  remember  that  the  dentin  matrix 
is  a  formed  material  of  the  same  general  class  as  other  intercellular 
substances  and  its  relation  to  the  odontoblasts  and  fibril  is  the  same  as 
other  intercellular  substance  and  the  cells  which  produce  them.  In 
other  words,  there  is  a  chemical  relation  between  the  cell  and  its  inter- 
cellular substance  in  which  the  cell  and  the  normal  circulation  of 
lymph  are  necessary  to  the  maintenance  of  the  intercellular  substance 
in  its  chemical  and  physical  properties.  When  the  cells  in  bone  are 
killed,  the  intercellular  substance  or  bone  matrix  becomes  a  foreign 
body  and  undergoes  chemical  and  physical  change.  When  the  pulp  is 
removed  from  the  dentin  the  dentin  matrix  becomes  a  dead  substance, 
a  foreign  body,  it  undergoes  physical  and  chemical  change  as  Black 
demonstrated  twenty-five  years  ago.  Dentin  from  a  pulpless  tooth  is 
very  much  more  easily  broken  than  that  from  a  vital,  tooth,  and  would 
be  expelled  from  the  body  were  it  not  for  the  fact  that  between  it  and 
any  other  vital  tissue  is  another  tissue,  the  cementum,  which  encloses 
the  dentin  and  its  vitality  is  not  destroyed  by  the  death  of  the  dentin. 
The  only  reason  that  a  pulpless  tooth  is  not  exfoliated  is  because  the 
dead  dentin  is  enclosed  in  living  cementum.^ 

The  question  as  to  what  becomes  of  the  dentinal  tubuli  and  whether 
they  may  produce  decomposition  products  or  split  proteid  elements 
which  reduce  the  vitality  of  neighboring  tissues  and  render  them  liable 
to  the  invasion  of  infection  cannot  be  answered  until  a  great  deal  of 
hard  work  has  been  done  in  the  laboratory. 

1  The  question  as  to  whether  the  death  of  the  dentin  affects  the  vitality  of  the  cemen- 
tum in  any  degree  is  a  matter  of  discussion  at  present. 


92    DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

In  the  opinion  of  the  author  very  Httle  is  really  known  about  the 
contents  of  the  dentinal  tubuli. 

Just  beneath  the  layer  of  odontoblasts  is  a  zone  which  contains 
very  few  connective-tissue  cells.  In  thin  sections,  especially  in  the 
body  of  the  pulp,  this  appears  as  a  clear  layer  about  half  as  thick  as  the 
layer  of  odontoblasts.  It  is  known  as  the  layer  of  Weil.  Just  beneath 
the  layer  of  Weil  the  connective-tissue  cells  are  especially  numerous 
and  form  a  more  or  less  distinct  layer  of  closely  placed  cells.  In  the 
rest  of  the  body  of  the  pulp  the  cells  are  about  uniformly  distributed 
throughout  the  intercellular  substance.  These  connective-tissue 
cells  are  of  the  characteristic  forms,  rather  small,  containing  a  small  but 
deep-staining  nucleus,  the  protoplasm  stretching  out  into  slender 
projections  in  two  directions  to  form  the  spindle  cells,  or  in  more  than 
two  directions  to  form  the  stellate  cells.  The  stellate  forms  are  more 
common  in  the  body  of  the  pulp,  the  spindle  form  in  the  canal  portions. 
The  round  cells  are  comparatively  few  in  number,  and  are  probably 
young  cells  which  have  not  yet  acquired  the  adult  form. 

Bloodvessels  of  the  Pulp. — ^The  blood-supply  of  the  pulp  is  ex- 
tremely rich,  several  arterial  vessels  entering  in  the  region  of  the  apex  of 
the  root,  often  through  several  foramina.  These  large  vessels  extend 
occlusally  through  the  central  portion  of  the  tissue,  giving  off  many 
branches  which  break  up  into  a  very  close  and  fine  capillary  plexus 
(Fig.  58).  From  the  capillaries  the  blood  is  collected  into  the  veins, 
which  pass  apically  through  the  central  portion  of  the  tissue.  A  very 
striking  peculiarity  of  the  bloodvessels  of  the  pulp  is  the  thinness  of 
their  walls.  Even  the  large  arteries  show  scarcely  any  condensation  of 
fibrous  tissue  around  them  to  form  the  usual  adventitious  layer,  and 
usually  contain  but  a  single  involuntary  muscle  fiber  representing  the 
media,  while  the  walls  of  even  the  large  veins  are  made  up  of  only  the 
single  layer  of  endothelial  cells  forming  the  intima  and  are  in  structure 
like  large  capillaries  (Fig.  59).  This  peculiarity  of  the  bloodvessel 
walls  is  of  great  importance  as  it  renders  the  tissue  especially  liable  to 
such  pathologic  conditions  as  hyperemia  and  inflammation. 

The  lymphatic  circulation  of  the  dental  pulp  and  the  presence  or 
absence  of  lymphatic  vessels  in  the  tissue  have  been  matters  of  dispute 
for  many  years. 

In  1909  Sweitzer  demonstrated  lymph  vessels  in  the  dental  pulp  by 
injection.^  Since  that  time  Sweitzer's  work  has  been  repeated  in  this 
country  and  the  direct  injection  of  lymph  vessels  in  the  cervical  glands 
through  the  dental  pulp  has  been  accomplished. ^ 

1  "Ueber  die  Lymphgefasse  des  Zahnfleisches  u.  der  Zahne  beim  Menschen  u.  bei 
Saugetieren,"  Arch.  f.  mikrosk.  Anat.  u.  Entwickl.,  1907,  Ixix,  p.  807;  1909,  Ixxiv,  p.  927. 

2  Kaethe  Dewey,  Frederick  B.  Noyes:  Dental  Cosmos,  1917. 


PULP 


93 


■.\  X', 


y  -I 


Fig.  58. — Diagram  of  the  bloodvessels  of  the  pulp.     (Stowell.) 


Fig.  59. — Dog's  head,  showing  lymphatic  glands  injected  from  dental  pulp. 


94     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

The  lymph  is  collected  in  very  delicate  vessels  that  have  been  fol- 
lowed to  theTegion  of  the  odontoblastic  layer.  The  vessels  pass  to  the 
apical  region  following  the  same  course  as  the  large  bloodvessels. 
Both  independent  vessels  and  perivascular  lymph  sheaths  have  been 
demonstrated.  The  vessels  leave  the  pulp  through  the  apical  foramina, 
anastomose  freely  with  those  of  the  peridental  membrane  in  the  apical 
portion,  and  pass  through  the  bone  to  the  inferior  dental  canal  in  the 
lower  jaw  and  the  infra-orbital  canal  in  the  upper.  They  have  been 
demonstrated  emerging  from  the  mental  and  infra-orbital  foramina 
and  followed  to  the  submaxillary  lymph  glands.  It  is  probable  that 
some  of  the  incisors  drain  to  the  submental  lymph  nodes  and  that 
probably  the  second  and  third  molars  communicate  with  lymph 
vessels  emerging  from  the  posterior  opening  of  the  inferior  dental  and 
infra-orbital  canals  and  pass  to  the  lymph  nodes  of  the  pharynx.  Much 
work  is  still  to  be  done  in  this  field.  There  is  also  some  experimental 
evidence  that  there  is  a  flow  or  circulation  of  lymph  in  the  tubuli  of 
the  dentin,  which  is  quite  logical  from  a  priori  reasoning. 

Nerve  of  the  Pulp. — Several  comparatively  large  bundles  of  medul- 
lated  nerve  fibers,  containing  from  six  or  eight  to  fifteen  or  twenty 
fibers,  enter  the  pulp  in  company  with  the  bloodvessels  and  pass 
occlusally  through  the  central  portion  of  the  tissue.  These  bundles 
branch  and  anastomose  with  each  other  very  freely.  Most  of  the  fibers 
lose  their  medullary  sheath  before  reaching  the  layer  of  Weil,  in  which 
position  they  form  a  plexus  of  non-medullated  fibers;  from  these  fibers 
free  endings  are  given  ofl^,  which  penetrate  between  the  odontoblasts. 
In  some  cases  these  have  been  followed  over  on  to  the  dentinal  ends  of 
the  odontoblasts,  but  in  no  instance  have  they  been  followed  into  the 
dentinal  tubuli. 

In  the  opinion  of  the  author  the  work  of  Carl  Huber  ^  though  done 
many  years  ago  remains  the  most  convincing  of  any  on  the  enervation 
of  the  dental  pulp.  Several  authors  have  claimed  to  demonstrate 
nerve  fibers  in  the  dentinal  tubuli,  but  in  the  opinion  of  the  author 
the  evidence  based  upon  the  gold  chlorid  method  alone  must  be  con- 
sidered as  unsatisfactory,  and  at  least  capable  of  other  interpretation. 

The  Functions  of  the  Pulp. — The  pulp  performs  two  functions,  a 
vital  and  a  sensory.  '^} 

The  vital  function  is  the  formation  of  dentin,  and  is  performed 
by  the  layer  of  odontoblasts.  This  is  the  principal  function  of 
the  pulp,  and  it  is  first  manifested  in  the  development  of  the  tooth 
before  the  dentinal  papilla  is  converted  into  the  dental  pulp  by  being 
enclosed  in  the  formed  dentin.     After  the  tooth  is  fully  formed  the 

1  Dental  Cosmos,  1898. 


PIG.  1 


FIG.  2 


FIG.   8 


Fig.     1. — Tooth     split    open,     showing     pulp    and    pulp     ehaniber    and. 
lymphatic  vessels   as  seen  with  magnification  of  about  lO  diameters. 
Fig.    2. — Injected  lymphatic  vessels  in  the  dental  pulp. 
Fig.    S. — Injected  perivascular  lymph  sheath. 


CEMENTUM  95 

vital  function  is  not  manifested  unless  the  pulp  is  stimulated  by  some 
excitation  affecting  trophic  centers  and  which  causes  the  formation  of 
secondary  dentin.  There  are  some  exceptions  where  the  formation 
is  entirely  local. 

The  Sensory  Function. — In  regard  to  sensation  the  pulp  resembles 
an  internal  organ.  It  has  no  sense  of  touch  or  localization,  and  responds 
to  stimuli  only  by  sensations  of  pain.  The  pain  is  usually  localized 
correctly  with  reference  to  the  median  line,  but,  aside  from  that,  is 
localized  only  as  it  is  referred  to  some  known  lesion.  If  several  pulps 
on  the  same  side  of  the  mouth  and  in  teeth  of  both  the  upper  and  lower 
arches  were  exposed  so  that  they  could  be  irritated  without  impressions, 
reaching  the  peridental  membrane,  and  the  patient  were  blindfolded, 
it  would  be  impossible  for  him  to  tell  which  of  the  pulps  was  touched. 
The  pain  originating  from  a  tooth  pulp  may  be  referred  to  the  wrong 
tooth  or  to  almost  any  point  on  the  same  side  supplied  by  the  fifth 
cranial  nerve. 

The  pulp  is  especially  sensitive  to  changes  of  temperature,  but  is 
incapable  of  differentiating  between  heat  and  cold;  this  fact  is  often 
made  use  of  in  differential  diagnoses  (see  Chapter  XVI).  The  pulp 
is  also  very  sensitive  to  traumatic  and  chemical  irritations,  even  when 
these  are  conveyed  to  it  through  the  agency  of  the  dentinal  fibrils. 
Dr.  Huber^  has  suggested  that  this  transmission  may  be  accomplished 
by  the  traumatic  or  chemical  action  upon  the  fibrils  setting  up  meta- 
bolic changes  in  the  odontoblastic  cells  which  act  as  stimuli  to  the 
sensory  nerves  ending  between  the  cells  of  that  layer. 

CEMENTUM. 

The  cementum  covers  the  surface  of  the  dentin  apically  from  the 
border  of  the  enamel  lapping  slightly  over  the  enamel  at  the  gingival 
margin  (Plate  I,  Fig.  1). 

This  is  undoubtedly  the  normal  and  ideal  relation,  though  in  many 
extracted  teeth  it  will  be  found  otherwise.^  It  forms  a  layer,  thickest 
in  the  apical  region  and  between  the  roots  of  bicuspids  and  molars, 
and  becoming  thinner  as  the  gingival  line  is  approached.  The  cemen- 
tum resembles  subperiosteal  bone  in  structure,  but  differs  from  it  in 
the  character  and  arrangement  of  the  lacunae  and  in  the  absence  of 
Haversian  systems;  the  layers  or  lamellae  of  the  cementum  also  are 
less  uniform  in  character  than  those  of  bone. 

The  function  of  the  cementum  is  to  furnish  attachment  for  the 
fibers  of  the  peridental  membrane  which  holds  the  tooth  in  its  position. 

1  Dental  Cosmos,  1898. 

2  Hopewell-Smith:  Normal  Histology,   p.    18. 


96     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

The  surrounding  tissues  are  never  in  physiologic  connection  with  the 
outer  surface  of  the  dentin,  except  to  form  cementum  over  it  or  to 
remove  its  substance  by  absorption;  and  when  absorption  of  the  dentin 
has  occurred  on  the  surface  of  a  root,  it  is  never  repaired  except  by  the 
formation  of  cementum  to  fill  up  the  cavity  and  reattach  the  membrane. 

The  cementum  is  intermittently  formed  during  the  functioning  of 
the  tooth,  being  added  layer  after  layer  over  the  entire  surface  of 
•the  root,  the  difference  in  thickness  of  the  tissue  in  the  gingival  and 
apical  portions  being  chiefly,  though  not  entirely,  due  to  the  difference 
in  thickness  of  each  layer  in  the  two  positions  (Plate  I,  Fig.  2).  The 
cementum  on  the  roots  of  newly  erupted  teeth  is  thin,  and  on  the  roots 
of  teeth  of  old  persons  is  thick.  This  continued  formation  of  cementum 
is  due  to  the  necessity  for  change  and  reattachment  of  the  fibers  of  the 
membrane. 

In  the  gingival  portions,  where  the  cementum  is  thin,  the  tissue  is 
clear  and  apparently  structureless,  and  usually  contains  no  lacunae; 
while  in  the  apical  half  and  between  the  roots  the  lacunae  are  numerous. 
In  general,  wherever  the  lamellse  are  thin,  the  lacunse  are  absent;  but 
where  the  lamellae  are  thick,  they  are  found.  The  canaliculi  which 
radiate  from  the  lacunse  are  not  as  regular  as  in  the  case  of  the  lacuna? 
of  the  bone.  Sometimes  they  are  numerous,  sometimes  few;  they  may 
extend  from  a  lacuna  in  all  directions,  or  they  may  be  confined  to  one 
side,  usually  the  side  toward  the  surface  of  the  cementum  (Plate  I, 
Fig.  3). 

The  cementum  is  penetrated  through  all  its  layers  by  fibers  of  the 
peridental  membrane  which  have  been  imbedded  in  the  matrix  of  the 
tissue  and  calcified  along  with  it.  The  first  layer — that  is,  the  one 
next  to  the  dentin — is  usually  structureless  and-  shows  no  fibers  in  it, 
at  least  in  its  inner  half.  In  ground  sections  the  imbedded  fibers  often 
appear  in  a  number  of  layers,  while  they  are  not  apparent  in  the  rest 
of  the  thickness.  This  is  because  just  before  and  just  after  the  for- 
mation of  the  layers  in  which  they  appear  the  fibers  were  cut  off  and 
reattached,  changing  their  direction,  so  that  in  the  other  layers  the 
fibers  are  cut  transversely  or  obliquely.  This  is  illustrated  in  Fig.  60. 
These  imbedded  fibers  are  very  numerous  in  some  places.  If  properly 
stained,  the  tissue  seems  almost  a  solid  mass  of  fibers.  In  ground  sec- 
tions they  have  sometimes  been  mistaken  for  minute  canals  from  the 
fact  that  they  are  not  always  as  fully  calcified  as  the  cementum  matrix, 
and  shrinkage  causes  the  appearance  of  little  open  canals. 

There  has  been  much  discussion  recently  of  the  relation  of  the  dentin 
and  cementum,  and  the  nourishment  of  the  cementum.  Much  of  the 
discussion  shows  lack  of  the  fundamental  considerations  of  cytology, 
tissue  structure,  nutrition,  metabolism,  and  other  biological  ideas. 


CEMENTUM 


97 


The  author  is  of  the  opinion  that  most  of  the  root  communications 
between  the  lacunse  and  canaHcuh  of  the  cementum  and  the  tubuH  of 
the  dentin  are  not  typical  of  the  tissue  if  they  ever  occur.  From  a 
study  of  the  formation  of  cementum  and  dentin  it  is  evident  that  the 
formation  begins  at  the  dento-cemental  junction  just  as  that  of  enamel 
and  dentin  begins  at  the  dento-enamel  junction.  The  formation  of 
dentin  proceeds  from  this  line  inward  and  that  of  the  cementum  out- 


FiG.  60. — -Two  fields  of  cementum  showing  penetrating  fibers:  Gt,    granular  layer  of 
Tomes;  C,  cementum  not  showing  fibers;  F,  penetrating  fibers.     (About  54  X.) 


ward.  The  formative  process  as  well  as  the  tissue  produced  is  sup- 
ported, for  the  dentin  by  the  pulp,  for  the  cementum  by  the  peridental 
membrane.  While  it  is  quite  evident  that  there  may  be  occasional 
communication  between  the  channels  in  the  dentin  matrix  and  those  in 
the  cemental  matrix,  it  seems  well  established  that  the  nourishment 
of  one  tissue  is  not  dependent  upon,  or  even  related  to,  the  other. 
The  relation  of  dentin  and  cementum  in  the  region  of  the  apex 
7 


98     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

of  the  root  becomes  very  complicated  because  of  the  way  in  which  the 
formation  of  the  root  apex  is  accomphshed,  and  the  structure  in  this 
region  becomes  important  in  the  pathology  of  the  region.^ 

Hypertrophies  of  the  cementum  (formerly  often  called  exostoses, 
or  excementoses)  are  very  common.  The  increased  thickness  may  be  of 
one  lamella  or  of  several  lamellse  in  the  region  of  the  hypertrophy,  or 
all  of  the  layers  from  first  to  last  may  take  part  in  it.  Small  local 
thickenings  of  a  single  lamella  are  seen  in  connection  with  the  peri- 
dental membranes  wherever  an  especially  strong  bundle  of  fibers  is  to 
be  attached  to  the  root  to  support  the  tooth  against  some  special 
strain. 

PERIDENTAL  MEMBRANE. 

The  peridental  membrane  may  be  defined  as  the  tissue  which  fills 
the  space  between  the  root  of  the  tooth  and  the  bony  wall  of  its  alveolus, 
surrounds  the  root  occlusally  from  the  border  of  the  alveolus,  and  sup- 
ports the  gingiva. 

It  is  important  to  emphasize  the  three  parts  of  the  membrane  and 
to  call  attention  to  the  fact  that  the  membrane  clothes  the  root 
occlusally  from  the  border  of  the  alveolar  process  as  far  as  the  tissues 
are  attached  to  the  cementum  and  supports  the  epithelium  of  the 
gingiva. 

There  has  been  much  discussion  as  to  the  origin  of  the  myeloplax 
or  giant  absorbing  cells.  Some  have  claimed  that  they  are  degenerate, 
fused,  osteoclasts^  It  seems  more  probable  to  the  author  that  they 
originate  from  the  endotheloid  cells  of  the  connective  tissue  which 
at  first  act  singly,  but  fuse  as  the  area  of  absorption  increases.  It  has 
been  referred  to  under  many  names,  as  pericementum,  dental  perios- 
teum, alveolo-dental  periosteum,  etc.  While  this  tissue  performs  the 
functions  of  a  periosteum  for  the  bone  of  the  alveolus,  it  differs  in  struc- 
ture from  the  periosteum  in  any  position,  so  that  any  name  including 
the  word  periosteum  or  implying  a  double  membrane  should  be  avoided. 

The  peridental  membrane  belongs  to  the  class  of  fibrous  membranes, 
and  is  made  up  of  the  following  structural  elements:  (1)  Fibers.  (2) 
Fibroblasts.  (3)  Cementoblasts.  (4)  Osteoblasts.  (5)  Osteoclasts. 
(6)  Epithelial  structures  which  have  been  called  the  glands  of  the 
peridental  membrane.    (7)  Bloodvessels.    (8)  Nerves.    (9)  Lymphatics. 

The  peridental  membrane  performs  three  functions:  a  physical 
function,  maintaining  the  tooth  in  relation  to  the  adjacent  hard  and 
soft  tissues;  a  vital  function,  the  formation  of  bone  on  the  alveolar 

1  Noyes :  Dental  Histology. 

2  Arey,  L.  B.:  Origin,  function  and  fate  of  the  osteoblast.  Am.  Jour,  of  Anatomy, 
February,  1920. 


PERIDENTAL  MEMBRANE 


99 


wall  and  of  cementum  on  the  surface  of  the  root;  and  a  sensory 
function,  the  sense  of  touch  for  the  tooth  being  exclusively  in  this 
membrane. 


Ap  -! 


Fig.  61. — Diagram  of  the  fibers  of  the  peridental  membrane:  G,  gingival  portion; 
Al,  alveolar  portion;  Ap,  apical  portion.  (From  a  photograph  of  a  section  from  incisor 
of  sheep.) 

The  fibrous  tissue  of  the  membrane  is  of  the  white  variety,  and  may 
be  divided  into  two  classes,  the  principal  fibers  and  the  indifferent 


100     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

or  interfibrous  tissue.  The  principal  fibers  may  be  defined  as  those 
which  spring  from  the  cementum  and  are  attached  at  their  other  end 
to  the  bone  of  the  alveolar  wall,  to  the  outer  layer  of  the  periosteum 


Fig.  62. — Longitudinal  section  of  peridental  membrane  from  young  sheep,  showing 
fibers  penetrating  cementum:  D,  dentin;  C,  cementum,  showing  embedded  fibers;  F, 
fibers  running  to  outer  layer  of  periosteum  covering  the  alveolar  process ;  F',  fibers  running 
to  the  bone  at  the  border  of  the  process;  B,  bone.     (About  80  X.) 


PERIDENTAL  MEMBRANE 


101 


covering  the  surface  of  the  alveolar  process  to  the  cementum  of  the 
approximating  tooth,  or  become  blended  with  the  fibrous  mat  of  the 
gum  supporting  the  epithelium.  They  were  so  called  by  Dr.  Black, 
not  only  because  they  form  the  principal  bulk  of  the  tissue,  but  they 
also  perform  the  principal  function  of  the  membrane,  the  support  of 
the  tooth  and  surrounding  tissues.  The  interfibrous  tissue,  also  of  the 
white  variety,  but  made  up  of  smaller  and  more  delicate  fibers,  is  found 
filling  spaces  between  the  principal  fibers  and  surrounding  and  accom- 
panying the  bloodvessels  and  nerves,  and  contains  the  lymphatics. 


Fig.  63. — Longitudinal  section  of  the  peridental  membrane  in  the  gingival  portion: 
D,  dentin;  A'',  Nasmyth's  membrane;  C,  cementum;  F,  fibers  supporting  the  gingiva; 
F^,  fibers  attached  to  the  outer  layer  of  the  periosteum  over  the  alveolar  process;  F^, 
fibers  attached  to  the  bone  at  the  rim  of  the  alveolus ;  B,  bone.     (About  30  X.) 


For  convenience  of  description  and  study,  the  peridental  membrane 
is  divided  into  three  portions:  the  gingival,  that  portion  which  sur- 
rounds the  root  occlusally  from  the  border  of  the  alveolar  process; 
the  alveolar,  the  portion  from  the  border  of  the  process  to  the  apex 
of  the  root;  and  the  apical  portion,  surrounding  the  apex  of  the  root 
and  filling  the  apical  region  (Fig.  61). 

The  principal  fibers  spring  from  the  cementum,  the  cementoblasts 
building  up  the  matrix^  around  them  and  then  calcifying  both  matrix 
and  fibers,  in  this  way  implanting  their  ends  into  the  siuface  of  the 
root.    In  Fig.  62  the  fibers  are  seen  passing  through  the  last-formed 


102     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

layer  of  cementum.  In  most  positions  the  fibers  as  they  spring  from 
the  cementum  appear  as  well-marked  bundles  of  fine  fibers.  A  short 
distance  from  the  surface  of  the  root  they  break  up  into  smaller  bundles, 
which  interlace  and  are  reunited  into  larger  bundles,  to  be  attached  at 
their  other  extremity  to  the  bone,  cementum,  or  fibrous  tissue. 

To  arrive  at  an  understanding  of  the  arrangement  of  the  fibers  of  the 
peridental  membrane,  they  must  be  studied  in  both  longitudinal  and 
transverse  sections.  In  longitudinal  sections  of  the  membrane  in  the 
gingival  portion  (Fig.  63)  the  fibers  springing  from  the  cementum  at 
the  gingival  line  pass  out  for  a  short  distance  at  right  angles  to  the 
long  axis  of  the  tooth  and  then  bend  sharply  to  the  occlusal^  passing 
into  the  gingiva  to  support  it  and  hold  it  closely  against  the  neck  of  the 
tooth.  These  fibers  are  most  numerous  on  the  lingual  side,  where  food 
is  brought  against  the  gingiva  with  force  in  mastication  and  tends  to 
crush  it  down.  In  the  middle  of  the  gingival  portion  the  fibers  pass 
out  at  right  angles  to  the  axis  and  are  blended  with  the  fibrous  mat  of 
the  gum  on  the  labial  and  lingual  sides,  or  are  attached  to  the  cementum 
of  the  adjoining  teeth  on  the  approximate  sides.  A  little  farther  from- 
the  gingival  line  the  fibers  are  inclined  slightly  apically,  passing  over 
the  border  of  the  process  to  be  attached  to  the  outer  layer  of  the  peri- 
osteum. These  fibers  are  especially  large  and  strong  and  form  what  has 
been  called  the  ligamentum  circulare.  Just  at  the  rim  of  the  alveolus 
the  fibers  are  inclined  slightly  apically  and  inserted  into  the  bone, 
forming  the  edge  of  the  process. 

In  transverse  sections  of  the  membrane  in  the  gingival  portion 
(Fig.  64)  the  fibers  spring  from  the  cementum  in  large  bundles;  at 
the  center  of  the  labial  surface  they  extend  directly  outward,  breaking 
up  into  smaller  bundles,  passing  around  bloodvessels  and  bundles  of 
fibers,  and  blending  with  the  fibrous  tissue  supporting  the  epithelium. 
Passing  mesially  and  distally  toward  the  corners  of  the  root,  the  fibers 
swing  around  laterally  and  pass  to  the  cementum  of  the  next  tooth. 
On  the  approximate  sides  the  fibers  suddenly  divide  into  smaller 
bundles,  which  wind  in  and  out  around  bloodvessels,  and  bundles  of 
fibers  which  pass  into  the  gingiva  and  are  reunited  into  large  bundles 
to  be  inserted  into  the  cementum  of  the  next  tooth.  On  the  lingual 
side  the  arrangement  is  like  that  of  the  labial,  except  that  the  distance 
to  which  the  fibers  of  the  membrane  can  be  followed  before  they  are 
lost  in  the  fibrous  mat  of  the  gum  is  usually  greater  than  on  the  labial. 

In  the  occlusal  third  of  the  alveolar  portion  of  the  membrane  the 
fibers  pass,  at  right  angles  to  the  axis  of  the  tooth,  directly  from  the 

1  In  describing  the  direction  and  inclination  of  peridental  membrane  fibers,  they  are 
always  traced  from  the  cementum  to  the  bone,  the  angle  with  the  horizontal  plane  being 
formed  at  the  surface  of  the  cementum. 


PERIDENTAL  MEMBRANE 


103 


Fig.  64. — -Transverse  section  of  the  peridental  membrane  in  tlie  gingival  portion  (from 
sheep):  E,  epithelium;  F,  fibrous  tissue  of  gum;  B,  point  where  peridental  membrane 
fibers  are  lost  in  fibrous  mat  of  the  gum ;  P,  pulp ;  F',  fibers  extending  from  tooth  to  tooth. 
(About  30  X.) 


Fig.  65. — Fibers  at  the  border  of  the  alveolar  process  (from  sheep):  D,  dentin; 
C,  cementum;  F,  fibers  extending  from  cementum  to  bone;  Bl,  bloodvessel;  5,  bone. 
(About  80  X.) 


104     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


Pd 


Cm 


y  -'  ■  y-' 


Al 


;A  '■■■ 


*S.. 


lV: 


''^J 


s- 


*i 


■  M-^. 


Al 


YiG  66  —Transverse  section  of  the  peridental  membrane  in  the  occlusal  third  of  the 
alveolar  portion  (from  sheep):  ikf,  muscle  fibers;  Per,  periosteum;  AZ,  bone  of  the 
alveolar  process;  Pd,  peridental  membrane  fibers;  P,  pulp;  D,  dentm;  Cm,  cementum. 


PERIDENTAL  MEMBRANE  105 

cementum  to  the  bone.  In  this  position  the  fibers  are  large  and  do  not 
break  up  into  smaller  bundles,  but  the  original  fibers  can  be  followed 
uninterruptedly  from  the  cementum  to  the  bone  (Fig.  65).  In  the 
middle  third  the  fibers  are  inclined  occlusally,  and  this  inclination 
increases  as  the  apical  third  is  approached.  In  the  apical  third  the 
inclination  is  greatest,  and  the  fibers  as  they  arise  from  the  cementum 
are  very  large  and  break  up  into  fan-shaped  fasciculi  as  they  pass 
across  to  the  bone.  In  the  apical  portion  the  fibers  radiate  from  the 
apex  in  all  directions  across  the  apical  region  and  spread  out  in  fan- 
shaped  bundles  like  those  in  the  apical  third  of  the  alveolar  portion. 

In  a  transverse  section  near  the  border  of  the  alveolus  (Fig.  66),  at 
the  center  of  the  labial  surface  of  the  root,  the  fibers  are  seen  to  extend 
directly  out  from  the  surface  of  the  root  to  the  bone  of  the  process, 
except  where  they  are  diverted  to  pass  around  bloodvessels.  Passing 
around  distally  at  the  corner  of  the  root,  the  fibers  swing  laterally  so 
as  to  be  almost  at  a  tangent  to  the  surface  of  the  root,  and  are  inserted 
much  farther  to  the  distal  on  the  wall  of  the  alveolus.  A  similar 
arrangement  is  noticed  at  the  other  corners  of  the  root,  though  these 
tangential  fibers  are  usually  more  marked  at  the  distal  than  at  the 
mesial  corners. 

Studying  the  arrangement  of  the  fibers  with  reference  to  the  physical 
function  of  the  membrane,  it  is  seen  to  be  the  best  that  could  be  devised 
to  support  the  teeth  against  the  force  of  mastication  and  to  support 
the  tissues  about  them.  In  the  gingival  portion  the  fibers  passing  from 
tooth  to  tooth  form  the  foundation  for  the  gingivae  between  the  teeth 
filling  the  interproximate  spaces;  so  that  if  these  fibers  are  cut  off  from 
the  cementum,  by  extending  a  crown  band  too  far,  or  by  the  encroach- 
ment of  calculary  deposits  beginning  in  the  gingival  space,  the  gingivus 
drops  down  and  no  longer  fills  the  interproximate  space.  In  the 
alveolar  portion  the  fibers  at  the  border  of  the  process  and  those  at 
the  apex  of  the  root  together  support  the  tooth  against  lateral  strain, 
while  those  in  the  rest  of  the  alveolar  portion  are  so  arranged  as  to 
swing  the  tooth  in  its  socket  and  support  it  against  the  force  of  occlu- 
sion (see  Fig.  61).  As  seen  from  the  transverse  section,  the  fibers  at 
the  occlusal  third  of  the  alveolar  portion  are  so  arranged  as  to  support 
the  tooth  against  forces  tending  to  rotate  it  in  its  socket. 

Cellular  Elements  of  the  Membrane. — The  fibroblasts  are  spindle- 
shaped  or  stellate  connective-tissue  cells  which  are  found  between  the 
fibers  as  they  are  arranged  in  bundles.  In  sections  stained  with  hema- 
toxylin they  take  the  stain  deeply,  and  the  fibers,  which  are  unstained, 
are  differentiated  by  the  cells  lying  in  rows  between  them.  The  number 
of  fibroblasts  in  the  membrane  decreases  with  age.  They  are  large 
and  numerous  in  the  membrane  of  a  newly  erupted  tooth,  and  com- 


106     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

paratively  small  and  few  in  the  membrane  around  an  old  tooth.  This 
is  characteristic  of  fibroblasts  in  other  positions.  The  fibroblasts  are 
shown  as  they  appear  in  a  hematoxylin-stained  section  with  low 
powers  in  Fig.  67,  which  gives  part  of  the  membrane  in  the  gingival 


Fig.  67. — Fibers  and  fibroblasts  from  transverse  section  of  membrane:  F,  fibers  cut 
transversely;  F^,  fibers  cut  longitudinally,  showing  fibroblasts.     (About  80  X.) 

portion  between  two  teeth.  The  cells  are  seen  as  spindle-shaped  dots 
which  mark  out  the  fibers;  at  F  they  are  seen  in  a  position  where  the 
fibers  are  cut  transversely.  While  these  cells  perform  the  same  func- 
tion for  the  cementum  as  the  osteoblasts  do  for  bone,  they  are  in  form 
very  different  from  the  osteoblasts.    The  cementoblasts  are  always  flat- 


FlG. 


-Cementoblasts.     (Drawing  by  Dr.  Black.) 


tened  cells,  sometimes  almost  scale-like,  and  when  seen  from  above  are 
very  irregular  in  outline.  This  irregularity  of  outline  is  caused  by  the 
cells  fitting  around  the  attached  fibers  of  the  membrane  so  as  to  cover 
the  entire  surface  of  the  cementum  between  the  fibers.    Fig.  68  from 


PERIDENTAL  MEMBRANE 


107 


a  drawing  by  Dr.  Black  shows  several  cementoblasts  as  seen  when 
isolated  by  teasing.  The  cementoblasts  have  a  central  mass  of  proto- 
plasm containing  an  oval  nucleus,  and  short  irregular  processes  which 
fit  around  the  fibers  as  these  spring  from  the  surface  of  the  cementum. 
Fig.  69  shows  them  in  section  perpendicularly  to  the  surface  of  the  root, 
where  they  are  crowded  between  the  fibers.  The  cementoblasts  often 
have  processes  projecting  into  the  cementum  like  those  from  the 
osteoblast,  but  processes  projecting  into  the  membrane  have  never 
been  demonstrated. 


Fig.  69. — Transverse  section,  showing  the  cellular  elements:  Fh,  fibroblasts;  Ec,  epithe- 
lial structures;  Ch,  cementoblasts;  Cm,  cementum;  D,  dentin.     (About  900  X.) 


In  the  formation  of  the  cementum  occasionally  a  cementoblast  be- 
comes enclosed  in  the  formed  tissue  filling  one  of  the  lacunae,  in  which 
position  it  becomes  a  cement  corpuscle. 

The  osteoblasts  of  the  membrane  cover  the  surface  of  the  bone, 
forming  the  wall  of  the  alveolus,  lying  between  the  fibers  which  are 
built  into  the  bone.  In  form  and  function  they  are  like  the  osteoblasts 
in  attached  portions  of  the  periosteum.    They  form  bone  around  the 


108    DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

ends  of  the  peridental  membrane  fibers,  building  them  into  the  sub- 
stance of  the  bone.    The  bone  thus  formed  over  the  wall  of  the  alveolus 


HB 


PdB 


Per 


Fig.  70. — Border  of  growing  process :  Cm,  cementum ;  Pd,  peridental  membrane ;  Pd.B, 
solid  subperidental  and  subperiosteal  bone  with  imbedded  fibers;  Ms,  medullary  space 
formed  by  absorption  of  the  solid  bone;  H.B,  Haversian-system  bone  without  fibers;  Per, 
periosteum.     (About  50  X.) 


PERIDENTAL  MEMBRANE 


109 


is  like  the  solid  subperiosteal  bone,  and  is  penetrated  throughout  its 
thickness  by  the  imbedded  fibers;  but,  as  with  the  subperiosteal  bone, 
it  is  constantly  being  penetrated  by  perforating  canals,  the  solid  bone 
being  removed  by  resorption  and  rebuilt  in  bone  with  Haversian  sys- 


PdM 


PdB 


HB 


Fig.  71. — Penetrating  fibers  in  bone:  PdM,  peridental  membrane;  Oh^,  osteoblasts  of 
peridental  membrane;  Ob^,  osteoblasts  of  medullary  space;  PdB,  solid  subperidental  and 
subperiosteaV bone  with  embedded  fibers;  Ms,  medullary  space  formed  by  absorption  of 
the  solid  subperidental  bone  with  embedded  fibers;  H.B,  Haversian-system  bone  without 
fibers  built  around  the  medullary  space.     (About  200  X.) 


terns.  This  process  is  shown  in  Fig.  70,  a  section  through  a  growing 
portion  of  the  process  around  a  permanent  tooth.  A  higher  power 
(Fig.  71)  shows  the  penetrating  fibers  and  the  formation  of  Haversian- 
system  bone  without  fibers,  in  the  body  of  the  process. 

The  osteoclasts,  or  myeloplaques,  are  bone-destroying  cells    (Fig. 


110     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

72) ;  they  act  not  only  upon  bone,  but  also  upon  cementum  and  dentin. 
They  are  oval  cells,  often  as  much  as  30  microns  in  diameter,  and  con- 
tain many  nuclei — from  two  or  three  to  fifteen  or  twenty.  They  are 
often  called  giant  cells.  The  osteoclasts  are  not  constantly  found  in 
the  membrane,  but  make  their  appearance  whenever  calcified  tissues 
are  to  be  destroyed.  In  order  that  they  may  act  upon  a  tissue  they  must 
lie  in  contact  with  its  surface,  and  therefore  the  first  step  in  absorption 
of  the  peridental  membrane  is  the  cutting  off  of  the  fibers  imbedded 


Fig.  72. — -Osteoclast  absorption  of  bone  over  permanent  tooth:  Oc,  osteoclasts;  B,  bone 
of  crypt  wall;  F,  fibrous  tissue  of  follicle  wall;  A,  ameloblasts.     (About  62  X.) 


in  the  bone  or  cementum.  Where  the  osteoclasts  act  upon  the  surface 
of  the  tissue  they  produce  bay-like  excavations,  in  which  they  lie,  and 
which  are  known  as  Howship's  lacunae.  These  excavations  are  shown 
in  Fig.  73,  though  the  osteoclasts  have  disappeared.  In  Fig.  74,  from 
a  ground  section,  the  basin-like  excavations  are  shown  filled  with 
newly-formed  cementum,  thus  leaving  in  the  tissue  the  record  of  an 
absorption  repaired.  In  absorption  of  the  roots  of  the  temporary  teeth 
the  osteoclasts  are  found  not  only  in  the  membrane  and  attacking  the 


PERIDENTAL  MEMBRANE 


111 


surface  of  the  root,  but  all  through  the  medullary  spaces  in  the  bone, 
removing  the  temporary  alveolar  process. 


Fig.  73.— Root  of  a  temporary  mcisor,  showing  absorption  and  rebuilding  of  cementum 
Urom  sheep):  G,  gingiva;  D,  dentin  -Cm,  cementum;  Ah,  absorption  cavity,  showing 
Mowship  s  lacunae;  Cm},  newly-formed  cementum.     (About  50  X  ) 


When  absorption  is  going  on  at  one  place  on  the  surface  of  a  root  a 
compensating  formation  of  cementum  is  going  on  at  another,  so  that 


112     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


not  all  of  the  fibers  of  the  membrane  are  cut  off.      This  is  illustrated  by 
sections  of  temporary  teeth  that  are  read}'  to  be  shed  (Fig.  75) } 


Fig.  74. — ^Record  in  the  calcified  tissue  of  an  absorption  repaired:  D,  dentin;  Cm,  cemen- 
tum  filling  absorption  cavity.     (About  40  X.) 

Epithelial  Structures  of  the  Membrane. — The  peridental  membrane 
contains  cellular  structures  of  epithelial  character  which  are  so  con- 
spicuous that  they  demand  consideration  though  their  nature  and 
origin  are  not  as  yet  fully  understood. 


Fig.  75. — Section  showing  absorption  of  the  tooth  of  a  sheep:  a,  cementum;  b,  osteo- 
clasts in  cementum  and  dentin;  c,  osteoclast  in  the  peridental  membrane. 

These  structures  were  first  well  illustrated  and  described  by  Dr. 
Black,  in  his  work  on  the  periosteum  and  peridental  membrane,  in 

1  Absorption  of  the  Roots  of  Teeth,  by  Newton  G.  Thomas,  Cosmos,  1920. 


PERIDENTAL  MEMBRANE 


113 


Fig.  76. — Diagram  of  glands  of  peridental  membrane.     (Black.) 


Fig.  77. — ^Epithelial  structures  of  the  peridental  membrane  (from  sheep) :  Fh,  fibro- 
blasts; Ec,  epithelial  structures;  Ch,  cementoblasts ;  Cm,  cementum;  D,  dentin.  (About 
468  X.) 


114     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

1887,  and  were  called  by  him  the  glands  of  the  peridental  membrane. 
About  the  same  time  von  Brunn^  described  what  are  probably  the  same 
structures,  and  which  he  regarded  as  embryonal  remains  of  the  inner 
layer  of  the  enamel  organ,  which  he  described  as  growing  down  over 
the  surface  of  the  root.  These  structures  appear  as  cords  of  epithelial 
cells  arranged  in  the  form  of  a  network  winding  between  the  fibers  of 
the  membrane,  very  close  to  the  cementum  and  surrounding  the  root 


Fig.  78. — Epithelial  structures  (from  sheep):  Fb,  fibroblasts;  Ec,  epithelial  structures; 
Cb,  cementoblasts ;  Cm,  cementum;  D,  dentin.     (About  700  X.) 

almost  to  the  apex.  This  arrangement  is  illustrated  in  Fi^.  76,  a  dia- 
gram by  Dr.  Black.  The  meshes  of  the  net  are  close  in  the  gingival 
portion  of  the  membrane,  but  grow  more  and  more  open  in  the  alveolar 
portion.  They  are  not  confined  to  the  membranes  of  young  teeth  or 
the  temporary  dentition,  as  Dr.  Black  has  shown  them  in  the  mem- 
brane of  a  tooth  from  a  man  seventy  years  old,  though,  like  all  of  the 


1  Archiv.  f.  mikros.  Anat.,  1887. 


PERIDENTAL  MEMBRANE 


115 


cellular  elements  of  the  membrane,  they  become  less  numerous  as  age 
advances.  These  structures  are  especially  well  shown  in  the  mem- 
branes of  the  pig  and  sheep.  Fig  77  shows  their  appearance  in  a 
transverse  section  of  the  root  of  an  incisor  of  a  sheep;  here  they  swing 
out  from  the  surface  of  the  cementum  and  back  again  in  loops,  winding 
in  and  out  among  the  fibers.  Studied  with  higher  powers  (Fig.  78), 
they  are  seen  to  be  made  up  of  epithelial  cells  with  large  oval  nuclei 
which  react  to  the  characteristic  epithelial  stains.    They  are  arranged 


Fig.  79. 


-Epithelial  structures:  Ec,  epithelial  cord,  apparently  showing  a  lumen;  Ch, 
cementoblasts;  Cm,  cementum;  D,  dentin.     (About  500  X.) 


in  cords,  though  sometimes  what  seems  to  be  a  lumen  of  a  gland  tubule 
can  be  found  (Fig.  79).  The  cords  are  invested  with  a  delicate  base- 
ment membrane,  but  no  special  relation  to  bloodvessels  has  been 
demonstrated.  The  attempt  to  show  their  connection  with  the  surface 
epithelium  has  thus  far  failed.  As  the  gingiva  is  approached  (Fig.  80), 
they  seem  to  swing  out  from  the  surface  of  the  root  and  are  lost  between 
the  projections  of  the  epithelium  lining  the  gingival  space.  There  is 
evidence  that  these  structures  are,  at  least  in  some  cases,  of  importance 
as  the  primary  seat  of  pathologic  conditions  of  the  membrane. 


116     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


Fig.  80. — Longitudinal  section:  Ej^,  epithelium  lining  lhe  gingival  spacf;  (Ig,  gingival 
gland,  so  called;  D,  dentin;  A'',  Nasmyth's  membrane;  Du,  duct-like  structure  stretching 
away  toward  the  gingiva  from  the  epithelial  cord,  seen  at  Ec;  Cm,  cementum,  separated 
from  the  dentin  by  decalcification.     (About  50  X). 


PERIDENTAL  MEMBRANE 


117 


Bloodvessels  and  Nerves  of  the  Membranes. — Bloodvessels. — The 

blood-supply  of  the  peridental  membrane  is  very  abundant.  Several 
vessels  enter  the  membrane  from  the  bone  in  the  apical  region.  These 
arteries  branch  and  divide,  forming  a  rich  network,  from  which  the 
capillary  vessels  are  given  off.  The  arterial  network  is  constantly 
receiving  vessels  which  enter  the  membrane  through  Haversian  canals 


Fig.  81. — Unstained  section,  showing  lymph  capillaries  of  the  tooth  side  of  the 
gingivae  and  their  drainage  through  the  ligamentum  circulare  to  the  peridental  mem- 
brane. 


opening  on  the  wall  of  the  alveolus,  and  in  this  way  the  size  of  the 
vessels  passing  occlusally  is  maintained.  Arterial  vessels  also  enter  the 
membrane  over  the  border  of  the  process.  This  double  or  triple 
supply  of  the  membrane  is  important,  as  it  maintains  the  health  of 
the  membrane  when  the  supply  entering  through  the  apical  region 
is  entirely  cut  off  by  alveolar  abscess.  While  the  arterial  supply  of 
the  membrane  is  very  rich,  the  capillaries  in  the  membrane  are  com- 
paratively few.  This  is,  however,  a  characteristic  of  connective-tissue 
membranes. 


118     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 


Fig.  82. — Transverse  section  of  the  peridental  membrane;  showing  injected 
lymphatic  vessels  (oc,  3;  obj.,  16  mm.;  reduced  about  one-tenth). 


-» 


•-  ^ 


:^>;^^ 


Fig.  83. — Transverse  section  just  at  the  apex  of  the  root,  showing  injected  lymphatic 
vessels  in  the  peridental  membrane  and  in  the  canals  passing  to  the  pulp  (oc,  2;  obj., 
16  mm.;  reduced  about  one-third). 


PERIDENTAL  MEMBRANE 


119 


Space  will  not  permit  an  extended  description  of  the  lymphatics 
of  the  dental  region;  for  this  the  reader  is  referred  to  other  and  more 
extended  treatises. 

The  mucous  membrane  of  the  mouth,  lips,  cheeks,  alveolar  process 
and  gums  gives  rise  to  a  very  rich  network  of  lymphatic  capillaries 
which  drain  through  a  limited  number  of  trunks  to  the  sub-mental, 
the  submaxillary  and  the  upper  group  of  deep  cervical  lymph  glands. 
The  capillaries  of  the  labial  and  buccal  slopes  of  the  alveolar  process 
including  those  from  the  outer  slopes  of  the  gingivae  pass  to  the  reflec- 
tion of  the  soft  tissue  from  the  bone  to  the  lip  or  cheek.  On  the  lingual 
side,  in  the  upper  arch,  they  pass  obliquely  backward  and  to  the  upper 


Fig.  84. — Injected  lymph  vessels  in  the  inferior  dental  canal. 


group  of  deep  cervical  nodes;  in  the  lower,  those  from  the  incisal 
region  probably  pass  to  the  submental  nodes,  while  those  from  the 
molar  and  bicuspid  region  join  the  collecting  trunks  from  the  lateral 
portions  of  the  tongue. 

The  course  of  this  drainage  is  important  in  the  effect  of  radical 
curetting  of  infected  areas  about  the  teeth. 

The  first  injections  of  the  lymphatics  of  the  peridental  membrane 
have  been  made  in  the  last  year  or  two.  As  a  result  of  this  work,  the 
following  statements  can  be  made  with  some  positiveness.  The  lym- 
phatics arising  in  the  papilla  under  the  epithelium  on  the  buccal  and 
lingual  slopes  of  the  gingivae  pass  outside  of  the  periosteum  over  the 


120     DENTAL  HISTOLOGY,  WITH  REFERENCE  TO  DENTISTRY 

alveolar  process  to  a  wreath  of  collecting  trunk  at  the  reflection  of 
the  soft  tissues  from  the  bone  to  the  lips  or  cheek.  The  lymphatics 
arising  in  the  papillee  of  the  connective  tissue  supporting  the  epithe- 
lium of  the  gingival  space  pass  close  to  the  cementum,  penetrate  the 
ligamentum  circulare  and  extend  in  the  interfibrous  tissue  with  the 
bloodvessels  and  nerves  through  the  peridental  membrane  to  the  apex 
of  the  root.  They  anastomose  with  the  vessel  in  the  bone  of  the  alveo- 
lar process.  At  the  apex  of  the  root  they  receive  the  vessels  from  the 
dental  pulp  and  pass  through  the  bone  to  the  inferior  dental  or  infra- 
orbital canal.  They  have  been  traced  emerging  from  the  anterior 
openings  of  these  canals,  and  to  the  submaxillary  lymph  nodes,  but  it 


Fig.  85 

is  probable  that  from  the  region  of  the  second  and  third  molars  they 
emerge  from  the  posterior  openings  of  these  canals  and  pass  to  the 
upper  groups  of  deep  cervical  nodes.  The  course  in  the  incisor  region 
is  also  not  positively  determined.  It  is  probable  that  some  of  the 
vessels  from  the  low^er  incisors  drain  through  the  submental  nodes  and 
those  from  the  upper  incisors  probably  become  superficial  on  the  outer 
surface  of  the  maxilla  or  on  the  floor  of  the  nose.  In  the  dog's  head 
illustration,  injections  were  made  only  in  the  canines  and  first  molars 
and  the  injecting  fluid  was  followed  throughout  its  course  to  the  sub- 
maxillary nodes. 

Nerves. — The  nerves  of  the  peridental  membrane  have  not  been 
sufficiently  studied  to  be  described  in  detail.    Six  to  eight  medullated 


PERIDENTAL  MEMBRANE  121 

nerve  trunks  enter  the  apical  region  in  company  with  the  bloodvessels, 
and  they  receive  other  trunks  through  the  wall  of  the  alveolus  and  over 
the  border  of  the  process,  but  the  manner  of  their  distribution  and  the 
nature  of  their  endings  are  not  known. 

The  Changes  which  Occur  in  the  Membrane  with  Age. — ^When  a 
tooth  is  erupted  the  roof  of  the  bony  crypt  in  which  it  was  enclosed 
in  the  body  of  the  bone  is  removed  by  absorption  and  the  crown 
advances  through  the  opening.  The  diameter  of  the  alveolus  at  that 
time  is,  therefore,  greater  than  the  greatest  diameter  of  the  crown,  and 


Fig.  86. — -Young  and  old  membranes  (from  sheep):  D,  dentin;  Cm,  cementum;  Cm^, 
thickening  of  cementum  to  attach  fibers  at  the  corner;  Pd,  peridental  membrane;  5,  bone 
forming  the  wall  of  the  alveolus;  P,  pulp.     (About  80   X.) 

the  peridental  membrane  which  fills  the  space  is  very  thick.  By  the 
formation  of  bone  on  the  wall  of  the  alveolus  and  the  formation  of 
cementum  on  the  surface  of  the  root  the  thickness  of  the  membrane  is 
reduced.  In  the  young  membrane  most  of  the  large  bloodvessels  are 
found  in  its  outer  half,  forming  a  rather  defined  vascular  layer  near  its 
center.  In  the  old  membrane  most  of  the  bloodvessels  are  found  very 
close  to  the  surface  of  the  bone,  often  lying  in  grooves  in  its  surface. 
Both  young  and  old  membranes  are  illustrated  in  Figs.  85  and  86,  which 
are  taken  from  the  temporary  teeth  of  a  sheep,  one  just  after  eruption 
and  the  other  shortly  before  the  time  of  shedding. 


CHAPTER  III. 

PREVENTIVE  DENTISTRY. 

By  RUSSELL  W.  BUNTING,  D.D.Sc. 

The  term  preventive  dentistry  has  been  given  a  very  flexible  inter- 
pretation and  has  included  a  wide  range  of  operative  and  prophylactic 
procedures.  Not  only  has  it  been  applied  to  the  prevention  of  dental 
disease,  but  also  to  the  prevention  of  general  diseases  which  may  result 
from  dental  or  oral  infection.  As  a  result  of  the  different  viewpoints 
of  writers  who  have  dealt  with  this  subject,  various  statements  and 
opinions  have  appeared  which  are  so  contradictory  and  confusing  that 
in  the  minds  of  many  the  exact  meaning  and  significance  of  the  term 
preventive  dentistry  is  not  clear.  Strictly  speaking,  preventive  dentis- 
try should  consist  of  the  employment  of  those  measures  which  will 
tend  to  prevent  dental  and  oral  diseases;  but,  as  will  be  pointed  out 
later,  the  successful  accomplishment  of  this  object  will  effectually 
prevent  many  general  bodily  diseases,  so  that  in  the  realization  of  one 
the  other  is  attained.  Preventive  dentistry  in  its  broadest  sense, 
therefore,  aims  not  only  at  the  prevention  of  dental  diseases,  but  also  at 
the  prevention  of  any  general  disorders  which  might  arise  as  a  result  of 
dental  disease.  These  two  conceptions  are  therefore  so  closely  related 
that  one  may  not  well  be  considered  apart  from  the  other. 

In  a  consideration  of  our  present  knowledge  regarding  the  prevention 
of  dental  disease,  it  must  be  admitted  at  the  outset  that  as  yet  no 
absolute  methods  of  control  have  been  found  by  which  an  immunity 
to  any  of  the  special  dental  affections  may  be  attained.  No  panacea, 
specific  drug,  or  vaccine  has  been  discovered  which  will  exert  a  definite 
protective  action  against  dental  diseases  after  the  manner  of  typhoid 
and  diphtheria  immunization.  Although  dental  diseases  are  not  abso- 
lutely preventable,  it  may  be  said  that  they  are  partially  or  relatively 
preventable,  for  by  the  employment  of  certain  measures  the  occur- 
rence of  dental  disease  may  be  decreased  and  in  many  cases  entirely 
eliminated.  And  further,  dental  disease  may  be  permanently  arrested 
if  taken  early  in  its  course,  whereby  the  extent  of  the  lesion  is  limited 
and  serious  destruction  of  the  tissue  prevented. 

Preventive  dentistry  therefore  may  be  said  to  consist  of  the  employ- 
ment of  all  those  measures  which  tend  to  decrease  the  inception  of 
oral  diseases  and  in  the  early  application  of  operative  procedures  to 
arrest  the  progress  of  lesions  which  have  already  occurred.     In  many 

(122) 


PREVENTIVE  DENTISTRY  123 

respects  the  practice  of  preventive  dentistry  is  not  unlike  the  present 
methods  of  preventing  tuberculosis.  Preventive  medicine  has  dis- 
covered no  infallible  cure  for  this  dread  malady,  but  has  found  that 
the  observance  of  proper  life  conditions  and  hygiene  will,  as  a  rule, 
successfully  prevent  its  occurrence  even  in  individuals  who  have  a 
tendency  toward  phthisis.  And  in  those  cases  in  which  the  disease  has 
already  begun,  if  taken  in  the  early  stages,  the  lesion  may  be  checked 
and  healing  effected.  At  the  present  time,  the  greatest  success  in  the 
prevention  of  dental  diseases  and  tuberculosis  lies  in  the  employment 
in  each  case  of  those  specific  measures  of  partial  prevention  which  tend 
to  inhibit  these  diseases.  It  is  to  the  application  of  these  measures 
of  prevention  to  dental  diseases  and  their  systemic  effects  that  this 
chapter  is  devoted. 

The  practice  of  dentistry  and  medicine  in  the  past  was  limited  to  the 
treatment  of  diseases  which  had  already  manifested  themselves  and  to 
the  repair  of  tissues  which  had  been  damaged  by  disease  or  injury. 
But  in  recent  years  both  professions  have  recognized  their  inability  to 
maintain  the  health  of  the  human  race  by  curative  measures  alone  and 
have  come  to  see  that  there  is  great  need  for  more  effective  means  of 
disease  prevention.  The  study  of  methods  by  which  diseases  may  be 
prevented  has  become,  therefore,  an  important  branch  of  dental  and 
medical  practice. 

In  the  field  of  dentistry,  the  greatest  thought  and  energy  have  been 
directed  in  the  past  toward  the  perfection  of  various  operative  pro- 
cedures by  which  the  dental  tissues,  which  have  been  damaged  by 
disease,  might  be  repaired,  and  their  functions  restored.  To  this  end 
dental  technics  have  been  developed  to  such  a  high  degree  of  perfection 
that  extensive  restorations  and  the  rehabilitation  of  badly  diseased 
mouths  have  been  made  possible.  Today,  therefore,  by  virtue  of 
modern  dental  art,  many  cases  which  formerly  would  have  been 
considered  hopeless  and  condemned  to  the  forceps  may  be  rebuilt  and 
restored  to  masticatory  efficiency  and  esthetic  appearance.  In  this 
manner  dentistry  has  endeavored  to  play  her  part  in  the  general 
scheme  of  public  health. 

But  in  the  light  of  recent  developments  in  medical  science  grave 
questions  have  arisen  as  to  the  safety  of  many  operative  procedures  in 
dental  practice.  This  question  was  most  forcibly  brought  to  our  atten- 
tion by  Wm.  Hunter,^  of  England  in  a  series  of  papers  in  which  he 
severely  arraigned  the  practice  of  dentistry,  especially  the  so-called 
"American  Dentistry"  as  carried  on  in  England.  He  stated  that  many 
dental  restorations,  such  as  gold  fillings,  crowns,  and  bridges  cover  and 

1  Hunter,  Wm. :  The  Role  of  Sepsis  and  Antisepsis  in  Medicine,  London  Lancet, 
January  14,  1911;  Dental  Cosmos,  July,    1918,  p.  585. 


124  PREVENTIVE  DENTISTRY 

conceal  septic  material  about  the  roots  of  teeth,  and  that  these  infec- 
tions constitute  a  grave  menace  to  the  health  of  the  individual.  He 
believed  that  these  infectious  organisms  might  enter  the  blood  stream, 
be  distributed  throughout  the  body,  and  give  rise  to  a  wide  range  of 
disturbances,  namely,  affections  of  the  digestive  tract  (ulcers,  colitis, 
enteritis,  etc.),  of  the  glands  (adenitis),  of  the  blood  (anemia,  and 
septicemia),  of  the  joints  (arthritis),  of  the  kidneys  (nephritis),  and  of 
the  nervous  system.  It  was  the  opinion  of  Hunter  that  these  septic 
teeth  were  retained  in  place  and  the  areas  of  infection  hidden  for  many 
years  by  reason  of  faulty  and  ill-advised  dental  operations  when,  for 
the  good  of  the  patient,  they  should  have  been  extracted  or  allowed  to 
exfoliate.  He  inferred  that  the  poor  people  who  could  not  afford  such 
dental  restorations  were  more  fortunate  than  those  who  could  and  did 
have  them  because  in  their  case  the  diseased  roots  would  tend  to  be 
exfoliated  and  the  peridental  infections  might  escape  to  the  surface 
rather  than  be  confined  in  the  tissues  and  enter  the  circulation. 

These  criticisms  at  first  aroused  a  storm  of  resentment  and  protest 
on  the  part  of  the  dental  profession.  They  believed  that  the  charges 
made  were  unwarranted  and  unjust  and  they  could  not  conceive  the 
possibility  that  skillful  works  of  dental  art  by  which  diseased  mouths 
had  been  made  serviceable  and  comfortable  could  be  anything  but 
beneficial  to  the  individual.  But  because  of  the  interest  which  was 
aroused  in  the  question,  extensive  and  careful  studies  of  the  peridental 
tissues  were  made  to  determine  the  prevalence  and  extent  of  peridental 
infection.  By  the  wide  application  of  improved  methods  of  dental 
roentgenographic  technic,  a  great  mass  of  data  has  been  gathered  and 
reported,  the  results  of  which  have  been  so  startling  that  they  have 
revolutionized  many  of  our  previous  concepts.  For  a  clear  under- 
standing of  these  findings  the  reader  is  referred  to  the  original  reports 
of  investigation,  a  partial  list  of  which  is  appended.^    The  data  which 

1  Rosenow  E.  C:  Elective  Localization  of  Streptococci,  Jour.  Am.  Med.  Assn., 
November  13,  1915,  p.  1687. 

Rosenow,  E.  C:  The  Relation  of  Dental  Infection  to  Systemic  Disease,  Dental 
Cosmos,  May,   1917,  p.  485. 

Rosenow,  E.  C:  The  Pathogenesis  of  Focal  Infections,  Jour.  Nat.  Dent.  Assn., 
February,  1918,  p.   113. 

Billings,  Frank:     Focal  Infection,  Jour.  Am.  Med.  Assn.,  September  12,  1914,  p.  899. 

Mayo,  C.  H. :  Constitutional  Diseases  Secondary  to  Local  Infections,  Dental  Review, 
April,  1913,  p.  281. 

Mayo,  C.  H. :  Mouth  Infection  as  a  Source  of  Disease,  Dental  Summary,  January, 
1915,  p.  1. 

Mayo,  C.  H.:  The  Control  of  Focal  Infections,  Dental  Cosmos,  November,  1918, 
p.  963. 

Hartzell,  T.  B.,  and  Henrici,  A.  T. :  Report  of  Mouth  Infection  Research  Corps  of 
the  National  Dental  Association,  Official  Bulletin,  Jour.  Nat.  Dent.  Assn.,  October,  1914, 
p.  48;  1915,  p.  333;  November,  1916,  p.  333;  May,  1917,  p.  477. 

Black,  A.  D.:  Roentgenographic  Studies  of  Tissues  Involved  in  Chronic  Mouth 
Infections,  Jour.  Am.  Med.  Assn.,  October  19,  1918,  p.  1279. 

Fischer,  Martin:  The  Relation  of  Mouth  Infection  to  Systemic  Disease,  Dental 
Summary,  August,  1915,  p.  607. 


PREVENTIVE  DENTISTRY  125 

were  obtained  by  these  and  other  students  of  the  subject  clearly  revealed 
the  fact  that  peridental  infection  and  sepsis  exist  about  the  roots  of 
teeth  far  more  commonly  than  previously  had  been  suspected.  Large 
and  small  areas  of  necrotic  change  were  discovered  in  the  bone  and 
peridental  membrane  about  the  apices  of  devitalized  teeth,  as  well 
as  deep  septic  pockets  about  the  roots  of  pyorrhetic^  teeth.  Upon 
examination  these  areas  were  found  to  contain  pure  or  mixed  cultures 
of  streptococci,  staphylococci,  pneumococci  and  other  organisms, 
among  which  the  Streptococcus  viridans  appeared  to  be  especially 
prominent.  Many  of  these  septic  areas  produced  no  pain  and  gave  no 
outward  evidence  of  their  presence  other  than  that  shown  by  the 
roentgenogram.  Clinical  histories  revealed  that  many  of  these 
infections  had  in  all  probability  existed  for  months  or  years  about 
the  apices  of  devitalized  teeth,  the  root-canals  of  which  were  incom- 
pletely filled,  and  in  deep  pockets  about  loose  pyorrhetic  teeth  which 
had  been  held  in  place  by  ligatures  or  bridge  work.  These  peridental 
infections  have  been  shown  to  occur  with  astonishing  frequency 
especially  where  the  state  of  oral  hygiene  and  the  method  of  treating 
and  filling  root-canals  of  teeth  have  been  of  an  indifferent  character. 
In  tabulations  made  in  the  large  clinics  of  the  great  cities,  it  was  found 
that  over  75  per  cent,  of  the  non-vital  teeth  were  septic.  It  is  true 
that  these  data  were  taken  from  patients  coming  from  the  poorer  classes 
for  whom  dental  services  had  been  of  an  inferior  grade,  but  it  was  also 
found  that  even  among  the  patients  of  the  most  skilled  operators  deep 
infections  occurred  with  great  frequency. 

The  question  then  arose  as  to  the  significance  of  these  peridental 
infections  and  their  possible  relationship  to  general  health.  It  was 
noted  clinically  that  many  patients  who  had  considerable  oral  sepsis 
were  also  suffering  from  certain  general  disturbances.  These  disturb- 
ances seemed  to  be  of  wide  range  but  the  most  prominent  and  frequent 
in  occurrence  were  joint  affections  (arthritis)  and  heart  lesions  (endo- 
carditis and  myocarditis).  Rosenow  and  others^  isolated  bacterial 
cultures  from  the  infected  peridental  tissues  and  injected  them  into 
animals  with  the  result  that  in  many  cases  the  animals  showed  bodily 
disturbances  similar  to  those  of  the  patient  from  whom  the  cultures 
were  taken.  That  is,  certain  organisms,  especially  the  Streptococcus 
viridans,  taken  from  peridental  infections  and  injected  into  the  circula- 
tion of  an  animal  had  the  ability  to  localize  in  the  joints,  heart,  or  other 
tissues  of  the  animal  and  produce  pathologic  disturbance.  Although 
the  theory  which  Rosenow  advanced  as  to  the  method  by  which  these 
bacteria  became  localized    (elective  localization)  has  not  received  uni- 

1  For  use  of  term  pyorrhea,  see  Chapter  XIII.  -  Loc.  cit. 


126  PREVENTIVE  DENTISTRY 

versal  corroboration,  the  fact  remains  that  septic  material  taken  from 
the  tissues  about  the  teeth  and  injected  into  animals  will  produce  in 
them  general  disturbances  of  bodily  health,  which  in  many  instances, 
are  closely  parallel  to  the  clinical  findings  of  the  patient  from  whom  the 
infectious  organisms  were  taken.  All  septic  areas  about  the  teeth  are 
therefore  looked  upon  today  as  potential  foci  of  general  infection  from 
which  organisms  and  their  products  may  and  frequently  do  spread  by 
way  of  the  lymph  and  blood-stream  to  the  various  tissues  and  organs  of 
the  body.  Clinical  observation  teaches  us  that  not  every  infection  of  the 
peridental  tissues  gives  rise  to  systemic  disorders,  for  in  many  instances 
these  tissues  are  seriously  infected  while  the  general  health  is  seemingly 
unimpaired.  In  cases  of  this  kind  the  local  tissue  reactions  are  so 
complete  that  they  effectually  confine  the  infectious  organisms  and 
prevent  their  spread  in  the  general  circulation.  But  there  is  always 
the  possibility  that  such  localized  infections  may  break  through  the 
protective  defenses  at  some  future  time,  especially  during  a  general 
decline  of  body  reactions  and  tissue  defense. 

At  the  present  time,  therefore,  there  remains  little  room  for  doubt 
that  systemic  infection  may,  and  frequently  does,  arise  from  localized 
areas  of  sepsis  about  teeth,  many  of  which  may  give  no  evidence  of  their 
presence  other  than  that  shown  by  the  roentgenogram.  Consequently 
dental  operative  procedures  and  oral  sepsis  have  come  to  be  recognized 
by  both  the  dental  and  medical  professions  as  matters  of  great  signi- 
ficance to  general  health.  No  longer  may  the  mouth  be  considered  as  a 
separate  and  independent  part  of  the  body,  but  rather,  it  must  be  viewed 
as  an  important  and  strategic  avenue  by  which  pathogenic  bacteria 
may  gain  entrance  to  the  general  circulation. 

As  a  result  of  this  newer  conception  of  oral  infection  and  the  manifest 
relationship  of  dental  health  to  the  general  health,  dentistry  is  confronted 
with  serious  problems  and  responsibilities.  Many  dental  operative 
procedures  which  in  the  past  have  been  considered  safe  and  well-founded 
are  now  known  to  be  dangerous  and  often  highly  injurious  to  the  health 
of  the  individual.  The  question  has  arisen  therefore,  "What  dental 
procedures  are  safe  and  sane?"  In  answer  to  this  question  a  very 
careful  study  of  all  departments  of  dental  practice  which  have  a  bearing 
upon  oral  sepsis  has  been  made  with  the  view  of  proving  the  safety  of 
each  operation  and  discarding  from  dental  practice  all  those  procedures 
which  are  unsafe.  Consequently,  the  viewpoint  of  practitioners  of 
dentistry  has  undergone  such  a  radical  change  that  tooth  conservation, 
which  was  formerly  considered  to  be  the  matter  of  greatest  importance, 
has  been  superseded  by,  and  made  secondary  to,  the  question  of  safety 
in  respect  to  oral  sepsis  and  systemic  infection.  Already  marked 
changes  have  occurred  in  dental  teaching  and  practice  and  it  is  reason- 


ORAL  SEPSIS  127 

able  to  expect  that  as  our  knowledge  of  oral  sepsis  shall  be  increased  by 
future  study  and  research,  further  modifications  will  be  made  in  opera- 
tive dentistry  to  insure  the  safety  of  its  procedures.  It  is  today 
generally  conceded  that  fillings.  cro\\Tis,  and  bridges  should  not  be 
placed  on  teeth  which  have  septic  areas  about  them  and  that  all  possible 
means  should  be  utilized  to  discover  the  presence  of  such  infection 
before  beginning  operative  procedures.  Severe  lesions  in  the  peridental 
tissues  either  apical  or  pyorrheal  are  no  longer  treated  with  the  hope 
of  cm'e,  but  on  the  contrary  the  affected  teeth  are  extracted  for  the 
safety  of  the  patient.  Indeed,  there  are  many  who  claim  that  no 
devitalized  teeth  should  under  any  circumstance  remain  in  the  mouth, 
believing  that  they  always  constitute  a  possible  source  of  infection. 
On  the  other  hand,  there  are  many  others  who  believe  that  it  is  possible 
to  fill  the  root  canals  of  devitalized  teeth  in  a  manner  that  is  above 
reproach  and  are  attempting  in  every  way  to  perfect  the  technic  of  this 
operation.  Operative  dentistry  then  is  undergoing  a  change  in  its 
policies  by  which  it  is  making  an  honest  attempt  to  meet  the  new 
situation  to  the  end  that  its  procedures  may  be  safe  and  sane  as  regards 
dental  sepsis  and  systemic  involvement.  And  not  until  all  dental 
operations  shall  be  so  ordered  that  the  possibility  of  oral  infection  is 
minimized  or  removed  will  dentistry  fulfill  her  duty  as  a  guardian  of 
public  health  or  be  fully  accepted  as  a  benefit  to  mankind. 


ORAL  SEPSIS. 

The  term  oral  sepsis  is  used  to  denote  a  relative  state  of  mouth  infec- 
tion. The  oral  cavity  is  never  sterile  but,  on  the  contrary,  continually 
harbors  various  forms  of  bacteria,  pathogenic  and  non-pathogenic,  in 
health  as  well  as  in  disease.  These  organisms  thrive  among  the  oral 
secretions  and  retained  foodstuffs,  living  in  s>Tabiotic  relationship  to 
each  other.  In  health,  the  mucous  membrane  presents  an  efficient  and 
continuous  barrier  against  infectious  organisms  by  which  the  mouth 
bacteria  are  prevented  from  entering *the  deeper  underlying  tissues. 
As  long,  therefore,  as  the  protection  is  complete,  the  oral  micro- 
organisms are  segregated  in  the  mouth  cavity  and  the  digesti^'e  tract 
and  are  of  no  apparent  significance  to  the  general  health.  Normally  the 
bacterial  flora  of  the  mouth  leads  a  low-grade,  saprophytic  existence 
quite  independent  of  the  body  as  a  whole.  But  when,  by  reason  of  poor 
mouth  hygiene,  quantities  of  food  debris  are  retained  about  the  teeth, 
fermentations  take  place  and  the  bacterial  flora  is  greatly  increased. 
In  such  cases  certain  t^^es  of  organisms  may  attain  a  high  degree  of 
virulence  producing  rapid  and  extensive  fermentation  thereby  changing 


128  PREVENTIVE  DENTISTRY 

the  bacterial  picture  of  the  oral  cavity  from  a  normal  low-grade  flora 
to  that  of  a  vicious,  harmful  overgrowth  of  microorganisms  capable  of 
destroying  the  protective  mucous  barriers  of  the  mouth  and  invading 
the  deeper  tissues.     This  latter  state  is  known  as  oral  sepsis. 

The  manifestations  of  oral  sepsis  present  a  wide  range  of  variation 
dependent  upon  the  type  or  types  of  organisms  which  predominate 
in  the  overgrowth,  the  quality  of  oral  hygiene,  and  the  general  health 
of  the  host.  Clinically,  two  general  classes  may  be  distinguished, 
namely  acute  and  chronic.  The  former  consists  of  open  and  manifest 
infections  which  rapidly  involve  the  mucous  surfaces  of  the  oral  cavity. 
They  excite  intense  inflammatory  reactions  in  the  gums,  the  cheeks, 
and  the  tongue  accompanied  by  more  or  less  ulceration  and  desquama- 
tion of  the  superficial  tissues.  To  these  the  general  term  stomatitis 
is  applied,  which  includes  a  wide  range  of  ulcerative  conditions  depen- 
dent upon  the  type  of  predominating  organism  and  the  severity  of  its 
proliferation.  As  a  rule,  these  acute  infections  run  a  rapid  and  virulent 
course  and  the  symptoms  which  they  produce  are  so  alarming  that  the 
attention  of  the  patient  and  the  operator  is  readily  attracted  to  them'. 
When  prophylactic  and  abortive  treatment  is  applied  they  are  promptly 
controlled  and  the  tissues  usually  return  to  normal  within  a  few  days. 

Unlike  the  acute  type,  the  chronic  forms  of  oral  sepsis  are  mild  and 
inconspicuous  in  their  action.  They  consist  in  an  overgrowth  of 
organisms  which  do  not  produce  ulceration  or  active  inflammatory 
reactions  in  the  tissues.  Thriving  upon  the  retained  foodstuffs  about 
the  teeth  and  in  mucoid  plaques  in  the  gingival  areas  they  set  up  a 
chronic  low-grade  irritation  in  the  gmn  tissues,  as  a  result  of  which 
chronic  inflammation  and  slow  degenerations  of  the  peridental  tissues 
ensue.  By  reason  of  the  insidious  manner  of  their  growth  these  chronic 
infections  may  be  easily  overlooked  and  frequently  may  only  be 
recognized  by  staining  the  teeth  with  a  disclosing  solution.  Conse- 
quently they  may  exist  in  a  mouth  unobserved  for  months  or  years  and 
slowly  accomplish  a  progressive  degeneration  of  the  peridental  tissues, 
thereby  gaining  entrance  to  the  underlying  deeper  structures. 

Recent  investigations  have  been  directed  toward  a  study  of  the 
various  organisms  which  are  involved  in  the  several  t^-pes  of  oral 
sepsis.  It  has  been  found  that  in  the  acute  ulcerative  types  of  infection 
and  in  abscesses  the  predominating  organisms  are  of  a  purulent,  hemo- 
lytic type  which  have  the  ability  to  destroy  tissue  rapidly  with  the 
formation  of  pus.  Among  others  Streptococcus  pyogenes.  Staphy- 
lococcus pyogenes  albus  and  aureus^  Bacillus  pyocyaneus  are  com- 
monly found.  Against  them  intense  inflammatory  reactions  are  set 
up  in  the  tissue  by  reason  of  which  their  course  is  limited  and  their 
activities  confined.    The  active  and  purulent  types  of  infection,  there- 


ORAL  SEPSIS  129 

fore,  being  restrained  by  the  protective  powers  of  the  tissues,  as  a  rule, 
do  not  tend  to  spread  far  from  the  original  seat  of  inoculation. 

In  the  subacute  or  chronic  forms  of  oral  sepsis  the  predominating 
organisms  are  usually  a  non-purulent,  non-hemolytic  type  among  which 
Streptococcus  viridans  occurs  with  the  greatest  frequency.  Various 
streptococcal  strains,  of  which  viridans  is  one  form,  may  be  demon- 
strated in  practically  every  case  of  non-purulent  gingivitis  and  pyorrhea 
and  in  the  periapical  affections  known  as  granuloma.  This  type  of 
organism  does  not  excite  active  tissue  reactions  but  rather  induces  in 
them  progressive  degenerations  against  which  the  tissues  have  little 
power  of  self  protection.  There  is,  therefore,  a  tendency  for  these 
chronic  t^^pes  of  infection  to  infiltrate  deeply  into  the  tissues  which 
they  attack  and  on  gaining  entrance  to  the  bloodvessels  of  that  region 
they  may  be  introduced  into  the  general  circulation. 

When  we  view  these  two  forms  of  oral  sepsis  in  the  light  of  their 
significance  to  the  general  health,  it  becomes  evident  that  they  are  not 
of  equal  importance.  In  former  times  the  purulent  type  of  infection 
was  looked  upon  with  the  greatest  concern,  and  indeed,  the  peridental 
abscess,  purulent  forms  of  pyorrhea  and  active  tissue  ulcerations  were 
the  only  infections  that  were  given  any  serious  consideration.  It  was 
recognized  that  these  infections  would  in  time  produce  marked  and 
often  extensive  degeneration  of  the  local  tissues  and  occasionally  the 
more  severe  types  resulted  in  general  septicemia.  But  more  recently 
we  have  come  to  have  a  greater  fear  of  the  insidious-  forms  of  bacterial 
invasion,  namely,  the  non-purulent  streptococcal  group  of  organisms 
which  manifest  a  greater  tendency  to  penetrate  into  the  deeper  tissues 
and  enter  the  general  circulation. 

The  true  significance  of  these  two  types  of  infection  and  the  manner 
of  their  action  may  be  expressed  in  terms  of  tissue  resistance. 
Nature  has  built  in  every  oral  cavity  a  complete  lining  which  offers 
resistance  to  the  entrance  of  all  kinds  of  organisms  into  the  underlying 
tissues.  It  is  only  by  injury  to  this  mucous  membrane,  or  the  teeth, 
that  oral  sepsis  may  gain  entrance  to  the  general  circulation.  And 
when,  either  by  accident  or  by  bacterial  erosion,  a  lesion  has  been  made 
in  the  protective  covering,  the  infectious  organisms  meet  in  the  tissues 
a  second  line  of  defense  which  consists  of  all  the  protective  reactions 
of  the  bodily  tissues;  namely,  phagocytosis,  bacteriolysis,  antitoxins, 
granulation  tissue,  etc.  By  these  reactions  the  tissues  seek  either  to 
overcome  and  destroy  immediately  the  infectious  organisms,  or,  failing 
in  this,  to  form  a  protective  wall  of  granulation  tissue  about  the  septic 
invader  to  limit  its  action  and  confine  it  to  one  locality.  This  wall 
at  first  consists  of  masses  of  lymphocytes  and  leukocytes  which  have 
rallied  to  the  spot  under  the  direction  of  chemotaxis,  and  many  new 
9 


130  PREVENTIVE  DENTISTRY 

and  rapidly  growing  bloodvessels  which  afford  a  very  rich  and  free 
blood  supply  to  the  part.  Later,  if  the  tissues  succeed  in  checking  the 
invasion,  this  limiting  wall  is  organized  into  a  more  permanent  line  of 
defense  by  the  growth  of  connective-tissue  fibers  until  the  infectious 
material  is  entirely  enclosed  in  a  fibrous  tissu  e  sac.  When  this  has  been 
accomplished,  the  bacteria,  as  a  rule,  are  effectually  confined,  although 
the  possibility  still  remains  that  they,  or  their  toxins,  may  make  their 
escape  in  limited  quantities  by  way  of  the  capillaries  which  enter  and 
leave  the  sac.  But  the  tissue  reactions  which  have  just  been  described 
are  not  always  complete.  They,  in  the  first  place,  are  dependent  upon 
the  type  of  bodily  health  and  general  activity  which  the  individual 
possesses.  When  the  general  health  is  good  the  local  reaction  to 
infection  will  be  far  more  vigorous  than  when  the  vitality  is  low.  In 
the  second  place,  as  the  local  tissue  reactions  arise  in  response  to 
bacterial  injury,  the  type  of  reaction  which  is  produced  will  be  deter- 
mined largely  by  the  type  of  invading  organism.  Against  the  acute 
purulent  types  of  infection  the  tissue  reactions  are  high  and,  as  a  rule, 
sufficient  to  check  and  control  effectually  the  invader,  while  against 
the  non-purulent  streptococcal  type  of  infection  the  protective  reactions 
are  usually  weak  and  insufficient  to  check  the  penetration  of  the  organ- 
isms into  the  tissues  and  the  circulation.  It  is  therefore  that  type  of 
infection  against  which  the  protections  are  weak  that  is  most  to  be 
feared,  inasmuch  as  even  in  healthy  individuals  the  tissues  are  fre- 
quently unable  to  combat  it  successfully,  but  are  seemingly  at  the 
mercy  of  the  invader. 

In  a  consideration,  therefore,  of  oral  sepsis  in  its  relation  to  systemic 
disease,  we  must  recognize  that  those  forms  of  infection  which  are  low 
grade  and  non-purulent  are  most  to  be  feared,  not  only  on  account  of 
the  inability  of  the  tissues  to  combat  them,  but  also  because  of  the 
fact  that  since  they  excite  no  active  tissue  reactions,  their  invasion  is 
insidious,  almost  imperceptible,  and  their  presence  may  be  overlooked 
easily.  It  is  then  to  the  control  of  this  type  of  infection  that  the 
greatest  attention  should  be  given  in  the  practice  of  preventive 
dentistry. 

In  a  study  of  methods  by  which  these  infections  may  be  controlled,  we 
are  led  to  consider  the  avenues  by  which  the  organisms  break  through 
the  protective  defenses  of  the  mouth :  that  is,  the  areas  of  the  oral  cavity 
which  are  most  susceptible  to  bacterial  invasion  and  which,  therefore, 
should  be  watched  most  carefully.  Practically  all  deep  infections  of 
the  oral  tissues  occur  in  one  of  two  general  localities;  the  one  through 
a  carious  defect  in  a  tooth  involving  the  pulp,  and  the  pulp-canal  and 
thence  to  the  periapical  tissues;  the  other  by  way  of  the  gingival 
crevice  about  the  neck  of  a  tooth  into  the  deeper  peridental  tissues. 


ORAL  SEPSIS 


131 


So  comprehensive  are  these  two  avenues  of  infection  that  could  they  be 
successfully  protected  and  closed,  practically  all  danger  of  oral  sepsis 
would  be  eliminated  and  systemic  disease  from  a  dental  source  would 
most  effectually  be  prevented.  It  is  therefore  to  the  guarding  of  these 
two  gateways  of  infection  that  preventive  dentistry  must  be  directed. 
The  question  next  arises  as  to  the  manner  in  which  these  invasions 
occur.  In  the  first  type  we  find  that  the  initial  step  is  a  lesion  in  a  tooth, 
a  carious  cavity,  which  is  laden  wath  infectious  organisms  charac- 
teristic of  the  mouth  flora.     As  soon  as  the  pulp  is  exposed,  these 


Fig.  87 


organisms  promptly  invade  the  pulpal  tissue,  through  which  they 
pass  out  through  the  apex  of  the  root  to  be  implanted  in  the 
periapical  tissues.  If  the  infection  be  purulent  in  tj^pe,  an  acute 
abscess  is  formed,  accompanied  by  pus  and  a  severe  inflammatory 
reaction.  If,  however,  the  infection  be  low  grade  and  non-purulent  in 
type,  a  mild  tissue  reaction  will  be  set  up  and  a  gradual  destruction  of 
tissue  will  be  effected  with  little  or  no  outward  signs  or  symptoms  in 
evidence  thereof.  At  the  present  time  we  do  not  fully  understand  the 
significance  of  these  lesions.    In  many  cases  it  seems  that  the  tissue 


132  PREVENTIVE  DENTISTRY 

is  able  to  construct  a  fibrous  tissue  wall  about  the  infection  forming 
a  so-called  granuloma.  Upon  examination  these  granulomata  are 
frequently  found  to  be  sterile,  from  which  it  is  inferred  that  the  organ- 
isms which  caused  the  lesion  have  been  overcome  by  the  bactericidal 
properties  of  the  surrounding  tissues.  But  many  of  these  non-purulent 
lesions  contain  pneumococci  and  Streptococci  viridans  which  may  act 
as  potential  foci  of  systemic  infection.  As  we  have  at  present  no  means 
at  hand  by  which  we  may  distinguish  clinically  the  dangerous  from 
the  benign  types,  all  granulomata  must  be  viewed  with  suspicion. 

The  successful  treatment  and  elimination  of  periapical  infections  are 
not  easily  accomplished.  As  a  rule  they  have  invaded  far  beyond  the 
end  of  the  root  so  that  the  treatment  of  these  lesions  through  the 
root-canals  is  uncertain  and  of  doubtful  value.  For  the  most  part, 
surgical  excision  of  the  root  and  curettage  of  the  infected  bone  through 
the  gum  tissues  (root  resection  or  apicoectomy)  is  the  only  efficacious 
manner  of  treating  all  such  cases  save  perhaps  the  more  incipient  forms. 
And,  indeed,  there  are  many  who  hold  that  no  tooth,  the  root-end  of 
which  has  been  seriously  affected,  should  in  any  case  be  retained. 

Every  tooth  therefore  in  which  the  pulp  has  died  from  bacterial 
invasion,  by  accident,  or  by  operative  procedures,  must  be  looked  upon 
as  a  possible  source  of  infection.  The  difficulty  of  completely  filling 
tortuous  root-canals  and  the  ease  with  which  infectious  matter  may  be 
introduced  during  the  operation  of  cleansing  and  filling  the  root-canals 
make  the  coefficient  of  error  and  the  probability  of  subsequent  infection 
exceedingly  high. 

A  study  of  roentgenograms  of  a  large  number  of  pulpless  teeth 
has  demonstrated  clearly  that  the  most  certain  root-canal  filling  is  a 
living  and  healthy  pulp.  That  is  not  to  say  that  root-canals  of  such 
a  tooth  cannot  be  filled  safely,  but  the  fact  should  be  emphasized 
that  the  successful  filling  of  root-canals  is  an  exceedingly  difficult  and 
hazardous  undertaking  which  should  be  attempted  only  under  the  most 
favorable  circumstances  and  performed  with  the  most  careful  technic. 

The  handling  of  pulpless  teeth  and  root-end  infections  is,  therefore, 
a  difficult  problem  in  dental  practice.  It  is  conceded,  however,  that 
periapical  infections  seldom  occur  on  teeth  having  vital  pulps.  If^ 
therefore,  the  pulps  of  all  teeth  could  be  kept  alive,  the  dangers  of 
periapical  infection  as  well  as  the  difficulties  of  root  canal  operations 
would  be  eliminated.  Going  still  further,  we  may  say  that  the  great 
majority  of  pulps  die,  either  directly  or  indirectly,  from  dental  caries. 
If  then,  we  could  either  prevent  caries  or  check  its  lesions  before  they 
involve  the  pulp,  practically  all  teeth  might  remain  alive.  It  follows_, 
therefore,  that  the  absolute  prevention  and  control  of  dental  caries 
would  automatically  result  in  the  prevention  of  periapical  abscesses 


PERIDENTAL  AFFECTIONS  133 

and  granulomata  with  all  their  attending  sequelae.  It  is  then  in  the 
prevention  and  control  of  dental  caries  that  the  greatest  hope  of  suc- 
cess lies,  by  closing  the  root-end  route  through  which  oral  infections 
may  enter  the  general  circulation. 

PERIDENTAL  AFFECTIONS. 

Turning  to  the  second  order  of  dental  infections,  the  peridental 
type,  we  find  somewhat  different  conditions  prevailing.  In  the  first 
place,  we  observe  that  of  all  the  mucous  coverings  of  the  mouth  the 
gingivae  are  most  vulnerable  to  the  attack  of  infectious  organisms. 
In  all  other  portions  of  the  mouth  the  mucous  membrane  with  its 
thickened  epithelium  offers  a  continuous  protective  barrier  against 
the  entrance  of  infectious  organisms.  But  in  the  process  of  erup- 
tion of  the  teeth,  holes  are  made  in  this  membrane,  one  for  each 
tooth,  which  apertures  persist  as  long  as  the  tooth  remains  in 
position.  Nature  attempts  to  protect  the  body  at  these  places 
and  to  close  the  door  against  the  entrance  of  infection  through  them 
by  causing  the  borders  of  each  opening  to  be  drawn  in  tightly  about 
each  tooth  with  the  formation  of  a  purse-like  flap,  the  gingiva, 
which  normally  hugs  tightly  about  the  neck  of  each  tooth.  On  the 
inner  side  of  this  gingival  flap  there  is  a  shallow  space  between  it  and 
the  tooth,  the  gingival  crevice,  at  the  bottom  of  which  the  mucous 
membrane  is  firmly  attached  to  the  pericementum  by  strong  connective- 
tissue  fibers.  In  health  these  gingival  tissues  are  thin,  firm,  and  so 
closely  adapted  to  the  teeth  that  they  offer  considerable  resistance  to 
the  entrance  of  infectious  organisms.  So  effective  is  the  gingival 
attachment  that  as  long  as  the  tissues  remain  in  perfect  normality 
they  successfully  protect  the  underlying  tissues.  But  when  masses  of 
infectious  material  remain  for  some  time  in  close  contact  with  the 
gingivae,  as  in  cases  of  faulty  oral  hygiene,  or  when  they  are  disturbed 
by  the  traumata  of  food,  calculi,  crowns,  bridges,  overhanging  fillings, 
etc.,  the  gingivae  are  irritated  and  become  inflamed.  Because  of  the 
fact  that  the  gingival  tissues  have  an  end-circulation,  it  follows  that 
slight  irritations  may  produce  profound  disturbances  such  as  active 
and  passive  congestion,  thrombosis,  and  other  inflammatory  reactions. 
In  the  event  of  any  of  these  conditions,  the  health  and  normal  function 
of  the  gingivae  are  profoundly  disturbed.  No  longer  do  these  tissues 
cling  tightly  about  the  teeth,  but  rather  do  they  swell  and  become  puffy, 
their  normal  tone  is  lost  and  they  fall  away  from  the  teeth.  In  this 
manner  the  gingival  crevice  is  opened  to  mouth  infection  and  an 
excellent  opportunity  is  offered  for  the  growth  of  infectious  organisms. 
The  surrounding  tissues  also,  being  disturbed  in  their  circulation  and 


134  PREVENTIVE  DENTISTRY 

metabolism  are  often  less  able  to  combat  these  infectious  invaders. 
The  result  is  that  deep  penetration  of  septic  organisms  takes  place. 
If  the  infection  be  of  a  purulent  type,  superficial  ulcerations  of  the 
gingival  tissues  are  produced  or  the  deeper  peridental  affections  char- 
acteristic of  true  pyorrhea  are  affected  consisting  of  the  formation  of 
a  pocket  along  the  side  of  the  root  of  the  tooth  and  the  production 
of  pus.  If  the  infection  be  non-purulent  in  type,  a  slow  disintegra- 
tion of  peridental  tissues  may  take  place  with  the  formation  of  pockets 
on  the  lateral  surfaces  of  the  root  in  which  no  pus  will  be  found.  In 
either  case,  the  infectious  organisms  have  passed  the  epithelial  barrier 
and  have  become  firmly  entrenched  in  the  deeper  tissues  where  they 
are  either  confined  by  the  local  tissue  reactions  or  spread  through  the 
circulation  to  remote  parts  of  the  body.  The  early  stages  of  this 
process  are  known  as  gingivitis  while  all  forms  of  deeper  penetration 
and  tissue  destruction  are  commonly  referred  to  under  the  general 
term  pyorrhea  alveolaris. 

Much  has  been  written  regarding  the  cause,  course,  and  effects  of 
the  so-called  pyorrhetic  types  of  infection  and  a  wide  diversity  of 
opinion  is  expressed.  At  the  present  time,  however,  the  more  rational 
students  of  the  subject  agree  that  all  of  those  conditions  begin  either 
as  an  inflammation  of  the  gingival  tissues,  or  that  the  presence  of 
gingivitis  is  an  integral  part  of  the  process.  If  this  be  true,  it  may  be 
argued  theoretically  at  least,  that  if  the  gingival  tissues  be  kept  in 
health,  the  inception  of  deep  peridental  infections  would  be  prevented. 
And  in  actual  practice  this  has  proved  to  be  true.  Few  observers 
today  believe  that  pyorrhea  can  occur  in  a  mouth  in  which  all  the 
gingivae  are  normal  and  in  perfect  health.  Practically  all  agree,  there- 
fore, that  the  most  successful  method  of  preventing  these  conditions 
lies  in  the  prophylactic  supervision  of  the  gingival  tissues. 

In  the  foregoing  consideration  of  the  two  most  important  and  almost 
sole  avenues  by  which  oral  sepsis  penetrates  the  natural  barriers  set  up 
against  it,  we  have  been  led  to  see  that  the  successful  prevention  of 
the  one  lies  in  the  prevention  and  control  of  dental  caries,  and  of  the 
other  in  the  prevention  and  cure  of  gingivitis.  It  may  be  said,  therefore, 
that  if  we  could  keep  the  teeth  intact^  and  the  gingivae  in  health, 
practically  all  danger  of  oral  sepsis  would  be  removed.  In  our  discus- 
sion of  preventive  dentistry,  therefore,  it  is  toward  the  control  of  these 
two  affections,  dental  caries  and  gingivitis,  that  the  greatest  attention 
will  be  directed. 

The  Prevention  of  Dental  Caries. — ^The  history  of  the  development 
of  our  present  knowledge  of  dental  caries  is  an  interesting  one.  Exami- 
nations of  crania  of  earlier  races  show  that  all  through  the  centuries 
every  type  of  people  has  been  afflicted  with  this  dental  affection.     In 


PERIDENTAL  AFFECTIONS  135 

the  early  Greek  and  Roman  writings  frequent  allusion  is  made  to  the 
pain  and  discomfort  of  decayed  teeth,  and  various  speculations  were 
indulged  in  regarding  the  cause  and  nature  of  the  process.  It  was  in 
the  18th  century  that  the  first  real  interest  was  showii  in  the  study  of 
dental  caries  and  through  the  years  that  followed  various  conflicting 
opinions  were  held  concerning  the  etiology  of  caries  and  about  each 
certain  definite  schools  of  thought  and  teaching  were  built  until  the 
time  of  ]\Iiller  who  gave  what  seems  to  be  the  true  solution  of  the 
problem. 

Prominent  among  these  hypotheses,  the  inflammation  theory  received 
a  wide  acceptance  from  1754  to  1835  and  was  championed  by  such 
men  as  Hunter,  Fox,  Bell,  Jourdain  and  many  others  who  believed  that 
the  hard  structures  of  the  tooth  possessed  a  blood  circulatory  system, 
similar  to  bone,  and  that  distiu-bances  of  circulation  resulted  in  a 
necrosis  of  the  tooth  quite  like  bone  necrosis.  They  therefore  looked 
upon  dental  caries  as  a  disease  which  originates  in  the  interior  of  the 
tooth,  probably  the  dentin,  and  progresses  outward  to  the  surface  of 
the  enamel,  the  process  being  alluded  to  by  Koliker  of  Philadelphia 
as  a  "bony  abscess." 

In  1835  Robertson  of  England  took  exception  to  the  inflammation 
theory  and  stated  that  it  "is  to  chemical  and  not  to  inflammatory 
action  that  the  destruction  of  teeth  must  be  attributed."  He  believed 
that  the  acids  of  caries  arose  from  the  decomposition  of  retained  food- 
stuffs about  the  teeth.  This  view  was  corroborated  by  Tomes  who,  in 
his  histological  studies  of  the  teeth,  found  that  the  dentin  contained 
no  bloodvessels  and  therefore  could  not  undergo  true  inflammation. 
He  turned  then  to  the  chemical  hypothesis  of  Robertson  as  also  did 
Magitot  who  in  1878  published  the  most  comprehensive  treatise  of  his 
time  in  which  he  described  dental  caries  as  a  disintegration  of  the  tooth 
by  chemical  substances  either  developed  in  the  mouth  or  introduced 
with  the  food.  Watt  in  1868  advanced  the  theory  that  free  nitric, 
sulphuric,  and  hydrochloric  acids  were  generated  in  the  mouth  as  a 
result  of  disintegration  of  foods  and  that  each  acid  produced  a  specific 
tjTDe  of  dental  caries. 

In  1867  Bridgeman  formulated  a  theory  in  which  he  considered  dental 
caries  a  destruction  of  the  tooth  by  acids  formed  from  electrolytic 
action.  He  believed  that  the  crown  of  the  tooth  and  the  giuns  were  of 
different  potential  and  that  they  with  the  saliva  as  an  electrolyte 
formed  a  battery  in  which  acid  substances  were  set  free  at  the  positive 
pole  (the  c^o^^^l)  which  acids  decalcified  the  enamel.  So  also  S.  B. 
Palmer,  in  1874,  claimed  that  recurrent  caries  of  a  tooth  beneath  a 
filling  resulted  from  a  difference  in  potential  between  the  filling  and  the 
dentin  and  in  the  presence  of  the  saliva  a  current  would  be  set  up  with 


136  PREVENTIVE  DENTISTRY 

the  formation  of  acids  which  either  decalcified  the  tooth  or  disintegrated 
the  fining. 

It  was  in  1867  that  Leber  and  Rottenstein  first  called  attention  to 
bacteria  as  a  causative  factor  in  the  carious  process.  They  succeeded 
in  staining  with  iodin  and  identifying  several  varieties  of  mouth 
organisms  in  carious  dentin.  They  believed  that  an  initial  lesion  of 
the  enamel  by  some  other  means  was  necessary  for  the  bacterial  propa- 
gation in  the  dentin.  At  the  World's  Medical  Congress  in  1881  Miles 
and  Underwood  in  an  exhaustive  treatise  on  the  subject  characterized 
dental  caries  as  "a  combined  action  of  acids  and  germs."  They 
believed  that  the  acids  which  were  active  in  the  process  were  produced 
by  bacterial  organisms  which  lived  upon  the  contents  of  the  dentinal 
tubuli. 

At  this  time,  the  knowledge  that  bacteria  caused  disease  was  largely 
theoretical  as  no  one  had  been  able  to  demonstrate  conclusively  the 
pathogenicity  of  these  organisms.  It  was  not  until  Koch  completed 
his  epoch-making  studies  in  1880  that  specific  bacteria  could  be  shown 
to  cause  definite  lesions  and  diseases.  This  he  accomplished  by  the. 
formulation  of  four  rules  or  tests  by  which  the  type  of  organism  might 
be  determined  and  its  responsibility  as  the  cause  of  disease  established. 
The  four  rules  of  Koch  are  as  follows: 

1.  The  microorganism  is  present  and  discoverable  in  every  case  of 
the  disease. 

2.  It  is  to  be  cultivated  in  every  case  of  the  disease. 

3.  Inoculation  from  such  culture  must  reproduce  the  disease  in 
susceptible  animals. 

4.  It  must  be  reobtained  from  such  animals  and  again  grown  in  pure 
culture. 

It  so  happened  that  W.  D.  Miller  was  closely  associated  with  Koch 
in  his  laboratory  at  the  time  he  was  pursuing  his  studies,  and  as  soon  as 
the  principle  was  definitely  established,  Miller  immediately  applied 
Koch's  four  rules  to  the  problem  of  dental  caries,  in  order  that  he 
might  determine  definitely  whether  or  not  the  process  was  due  to 
bacterial  action.  It  was  diu-ing  the  following  year  that  he  gave 
out  the  results  of  his  studies  in  what  is  now  known  as  the  Mil- 
lerian  theory  of  dental  caries.  Briefiy,  it  may  be  stated  as  follows: 
dental  caries  is  primarily  a  decalcification  of  the  enamel  and 
dentin  of  the  tooth  by  organic  acids  which  ha^e  resulted  from  the 
fermentation  of  carbohydrates  in  the  mouth  and  is  usually  asso- 
ciated with,  and  localized  by,  mucoid  plaques  or  films.  Sec- 
ondarily the  decalcified  dentin  is  disintegrated  by  a  proteolytic 
process.  The  bacteria  which  produce  the  initial  lesion  of  enamel 
caries  are  not    a  specific  variety  but  a  relatively  large   group   of 


PERIDENTAL  AFFECTIONS  137 

organisms  which  have  the  abihty  to  form  acids  when  acting  on 
carbohydrates.  The  process  of  dental  caries  is  therefore  infective 
in  type  but  certain  other  attending  conditions  are  necessary  for  the 
bacterial  action  to  be  effective;  namely,  carbohydrate  food  material, 
and  a  protective  covering  by  which  the  acids  formed  may  be  held 
against  the  tooth  and  protected  from  dilution  and  neutralization  by 
the  salivary  secretions.  Under  this  so-called  mucoid  plaque  the 
process  of  acid  production  and  enamel  dissolution  may  go  on  unmolested 
with  the  result  that  a  lesion  in  the  tooth  is  accomplished.  After  the 
initial  cavity  is  once  formed,  the  bacteria  advance  deeper  and  deeper 
into  the  tooth  progressively  decalcifying  the  enamel  and  the  dentin 
as  long  as  they  are  undisturbed.  The  theory  which  Miller  thus 
formulated  has  remained  until  today  as  the  only  tenable  concept  of  the 
caries  process  which  has  so  far  been  advanced. 

Although  the  Millerian  theory  has  given  us  a  fairly  definite  picture 
of  the  manner  in  which  dental  caries  operates,  it  did  not  reveal  the 
methods  by  which  the  process  may  be  prevented.  Miller  later  turned 
his  attention  to  this  phase  of  the-^subject  and  spent  considerable  time 
in  the  study  of  caries  prevention.  He  first  sought  for  some  form  of 
antiseptic  by  which  he  might  eliminate  mouth  infection.  He  found  it 
impracticable  and  virtually  impossible  to  continuously  rid  the  mouth 
of  acid-producing  organisms,  so  that  he  was  convinced  that  means  of 
caries  prevention  did  not  lie  in  the  use  of  antiseptics  or  bactericides. 
Then  he  began  investigation  of  the  methods  of  mechanically  cleansing 
the  mouth  and  of  reducing  the  amount  of  carbohydrate  and  infective 
materials  about  the  teeth  by  means  of  the  tooth  brush  and  dentifrices. 
This  line  of  attack  he  was  still  pursuing  at  the  time  of  his  death. 

Extension  for  Prevention.^ — Since  the  time  of  Miller,  many  valuable 
additions  have  been  made  to  our  knowledge  of  the  subject,  but  among 
these  there  are  few  concrete  suggestions  as  to  the  practical  control 
of  the  process.  Of  these  the  earliest  method  and  undoubtedly  the 
most  practical  one,  so  far  advanced,  is  the  excavation  of  cavities  which 
have  already  begun  in  the  teeth  and  the  filling  of  the  defects  with  a 
substance  which  will  arrest  the  process  and  preclude  a  subsequent 
infection.  This  procedure  has  received  its  most  rational  and  successful 
application  when  carried  out  according  to  the  principles  outlined  by 
G.  V.  Black,  known  as  "Extension  for  Prevention."^  Many  have 
observed  that  caries  has  a  tendency  to  occur  on  certain  definite  areas  of 
the  tooth  such  as  the  approximate  surfaces,  and  in  the  sulci  of  the 
occlusal  surfaces,  while  it  seldom  occurs  on  the  angles  of  the  teeth  or 
the  cusps.     It  is  argued  that  if,  in  the  preparation  of  a  cavity,  the  walls 

1  Black,  G.  v.:     The  Management  of  Enamel  Margins,  Dental  Cosmos,  1891,  p.  85. 


138  PREVENTIVE  DENTISTRY 

might  be  carried  outside  of  the  susceptible  areas  to  those  of  relative 
immunity,  the  liability  of  recurrence  of  caries  would  be  greatly  lessened. 
The  rationale  of  this  method  has  been  supported  by  years  of  clinical 
evidence  that  leaves  little  room  to  doubt  its  efficacy  in  caries  limitation. 
It  is  true  that  many  advocates  of  this  principle  have  been  overzealous 
in  its  application,  carrying  the  extension  of  cavities  to  great  extremes 
and  needlessly  sacrificing  tooth  structure;  but  those  who  have  extended 
cavities  advisedly  and  with  due  consideration  of  other  factors  involved, 
have  been  rewarded  with  a  high  degree  of  success.  It  follows  therefore 
that  the  early  detection  of  caries  defects  in  teeth  and  the  successful 
repair  of  these  lesions  in  accordance  with  the  present  approved  methods 
of  operative  dentistry  constitute  the  most  effective  means  of  controlling 
caries  when  once  the  process  has  been  inaugurated.  The  application 
of  these  principles  in  operative  dentistry  is  fully  considered  in  a 
succeeding  chapter. 

The  Oral  Hygiene  Movement. — About  ten  years  ago  examinations  of 
children  in  public  schools  clearly  revealed  that  a  great  majority  of  the 
children  were  suffering  from  dental  defects  and  severe  oral  sepsis  for . 
which  they  were  receiving  little  or  no  remedial  care.  So  apparent  was 
the  need  of  dental  services  that  municipal  dental  dispensaries  were 
instituted  in  the  schools  for  the  gratuitous  care  of  the  children.  The 
work  accomplished  was  mainly  that  of  cleansing  the  mouths  and 
teaching  the  children  to  keep  them  clean.  On  the  assumption  that 
dental  caries  is  a  filth  disease,  it  was  hoped  in  this  manner  to  limit  to  a 
degree  the  occurrence  of  caries,  and  to  reduce  the  oral  sepsis  present. 
In  addition  to  cleansing  the  teeth,  inspection  was  made  at  regular 
intervals  and  cavities  were  filled  promptly  in  order  that  a  minimum 
amount  of  damage  might  be  done  by  the  carious  process.  The  results 
which  have  been  attained  have  been  so  gratifying  that  school  clinics 
have  come  into  almost  universal  adoption  and  have  proved  to  be  of 
real  economic  value. 

A  further  extension  of  this  service  has  been  more  recently  made  in 
the  establishment  of  similar  dental  clinics  for  the  benefit  of  workers 
in  various  mercantile  plants  and  factories.  Regular  dental  examina- 
tions of  the  employes  are  made  and  advice  given  them  regarding  the 
care  of  their  mouths.  The  only  operations  performed  are 'brief  pro- 
phylactic treatments,  extractions,  and  emergency  relief  of  pain,  the 
patients  being  referred  to  the  family  dentist  for  permanent  restorations 
and  fillings.  Over  sixty  dental  clinics  of  this  kind  are  now  in  operation 
in  this  country.  Without  exception  they  have  proved  to  be  of  great 
benefit  to  the  employes  of  the  institutions  in  which  they  are  operating, 
and  have  produced  a  marked  increase  in  the  efficiency  of  the  whole 
organization. 


PERIDENTAL  AFFECTIONS  139 

Oral  Prophylaxis. — A  most  exacting  regimen  of  oral  hygiene  has  been 
advocated  and  practiced  by  certain  members  of  the  profession.  Acting 
upon  the  hypothesis  that  "a  clean  tooth  never  decays,"  they  spend 
considerable  time  in  polishing  the  several  surfaces  of  each  of  the  teeth 
in  the  mouth  in  order  that  they  may  be  easily  cleansed  by  the  patient. 
They  enlist  the  cooperation  of  their  patients  and  instruct  them  in  the 
performance  of  a  vigorous  and  thorough  daily  care  of  the  mouth. 
Such  patients  are  seen  regularly  once  a  month  for  the  purpose  of  cleans- 
ing those  teeth  which  were  habitually  missed  and  encouraging  the 
patients  to  perfect  the  personal  care  of  their  mouths.  This  method  of 
practice,  which  is  known  as  oral  prophylaxis,  has  been  followed  more 
or  less  extensively  by  a  large  number  of  dental  practitioners.  Perhaps 
the  periodontists  have  attained  the  highest  degree  of  efficiency  in  oral 
prophylaxis,  while  other  general  practitioners  have  adopted  the 
principles  wdth  varying  degrees  of  thoroughness.  There  is  also  a 
difference  of  opinion  as  to  whether  prophylaxis  actually  prevents  dental 
caries.  Certain  practitioners  affirm  that  they  are  able  to  eliminate 
practically  all  caries  from  the  mouths  of  patients  so  treated.  In 
evidence  they  submit  many  cases  of  individuals  who  have  been  sus- 
ceptible to  dental  caries,  who  cease  to  have  cavities  occur  under  the 
regimen  of  oral  prophylaxis,  and  cases  of  women  who  have  been  carried 
through  the  susceptible  period  of  pregnancy  without  dental  defect. 
Many  other  practitioners  having  rigorously  carried  out  this  method  of 
strict  oral  prophylaxis,  or  a  modification  of  it,  state  that  they  have  been 
able  to  stop  the  inception  of  caries  in  a  large  number  of  patients  who 
previously  had  been  susceptible  to  a  marked  degree.  The  more  con- 
servative, however,  do  not  as  yet  believe  that  immunity  from  dental 
caries  can,  in  all  cases,  be  obtained  in  this  manner,  but  that  in  a  large 
majority  its  rate  of  occm"rence  is  decreased  and  occasionally  it  may  be 
entirely  prevented  by  the  thorough  and  continuous  practice  of  oral 
prophylaxis.  Those  who  have  carried  out  this  method  with  a  less 
degree  of  thoroughness,  have  found  little  or  no  benefit  resulting  from  it 
other  than  the  general  decrease  of  oral  sepsis. 

The  diversity  of  opinion  regarding  the  value  of  oral  hygiene  and 
prophylaxis  as  a  caries  preventive,  has  led  to  considerable  uncertainty 
in  the  minds  of  many  as  to  the  rationale  of  its  adoption.  The  familiar 
picture  of  apparently  clean  mouths  being  vigorously  attacked  by  dental 
caries,  and  filthy  mouths  that  are  wholly  immune,  is  to  many  a  direct 
contradiction  of  the  slogan  "clean  teeth  do  not  decay."  They  are, 
therefore,  unwilling  to  subscribe  to  or  put  into  practice  the  principles 
of  strict  oral  prophylaxis  with  the  hope  of  preventing  dental  caries. 
Rather  do  they  look  and  hope  for  the  discovery  of  some  other  control- 
lable factor  in  the  process  of  caries  by  which  more  definite  and  tangible 


140  PREVENTIVE  DENTISTRY 

results  may  be  obtained.  Let  us,  then,  at  this  time  consider  what  other 
methods  have  so  far  been  suggested  by  dental  research  for  the  solution 
of  this  problem. 

Sulphocyanate  in  the  Saliva. — In  1900  Micheals  of  Paris  reported 
studies  which  he  had  made  of  the  saliva  and  its  relation  to  dental  caries, 
stating  that  the  secretions  of  caries  susceptibles  differed  from  those  of 
caries  immunes.  Among  other  constituents  he  noted  a  difference  in 
the  amount  of  sulphocyanates  which  he  considered  to  be  significant. 
Acting  on  this  suggestion,  a  large  group  of  men  in  this  and  other 
countries,  began  a  systematic  search  of  the  salivas  of  carious  and  non- 
carious  mouths  and  a  wide  interest  was  shown  in  the  investigation. 
Many  reported  that  a  relationship  did  exist  between  the  sulphocyanates 
and  dental  caries,  and  suggested  that  potassium  sulphocyanate  be  fed 
to  individuals  who  were  susceptible  to  dental  caries  for  the  purpose 
of  establishing  immunity  to  that  disease.  Perhaps  no  other  form  of 
caries  prevention  has  received  the  attention  this  received  for  a  time;  but 
later  investigations  discredited  the  premises  of  the  theory  and  resulted 
in  its  abandonment  by  all  save  a  few  of  its  most  ardent  supporters. 

Glycogen  in  the  Saliva. — Michaels  also  stated  that  the  saliva  con- 
tained glycogen  as  a  variable  constituent^  and  that  it  was  increased 
in  amount  by  excessive  carbohydrate  diets  and  by  diabetes.  Follow- 
ing this  line  of  thought.  Kirk  has  written  voluminously  upon  the  effect 
of  excessive  carbohydrate  diets  as  productive  of  glycogen  in  the  salivary 
secretions  which  in  turn,  he  believes,  furnishes  pabulum  for  lactic  acid 
fermentation  and  dental  caries.  As  a  caries  preventive,  he  suggests 
the  limitation  of  carbohydrates  in  the  diet.  There  is  little  doubt  that 
carbohydrates  are  active  factors  in  dental  caries  for  without  their 
presence  in  some  form,  lactic  acid  fermentation  could  not  take  place. 
But  the  assertion  that  the  most  important  source  of  carbohydrates  in 
oral  fermentation  and  dental  caries  is  to  be  found  in  the  salivary 
secretions  is  open  to  serious  objections.  In  a  former  contribution,^ 
we  have  reported  analyses  made  of  the  total  carbohydrate  content  of  a 
series  of  salivas,  comparing  the  results  obtained  to  the  caries  suscepti- 
bility in  each  case.  By  the  most  exact  methods  we  were  able  to  demon- 
strate only  the  most  minute  quantities  of  carbohydrate  which,  when 
compared  with  the  sugars  and  starches  habitually  retained  in  the 
mouths,  we  deemed  to  be  too  insignificant  to  be  given  serious  con- 
sideration in  the  process  of  caries.  Moreover,  we  were  not  able  to 
find  any  analogy  between  the  slight  glycogen  variations  of  the  samples 
tested  to  the  caries  susceptibility  of  the  individuals  from  whom  they 
were  taken. 

1  Bunting  and  Rickert:     Dental  Caries,  Jour.  Nat.  Dent.  Assn.,  No.  4,  p.  16. 


PERIDENTAL  AFFECTIONS  141 

In  a  series  of  articles  which  he  is  now  pubUshing,  Herman  Prinz^ 
states  that  he  has  made  exhaustive  search  in  saHvas  to  determine  the 
presence  of  carbohydrates  and  glycogen  and  has  been  unable  to  find 
them.  He  definitely  denies  the  presence  of  sugars  in  the  normal 
saliva. 

On  the  other  hand,  it  is  a  matter  of  common  observation  that  millers, 
bakers,  and  confectioners  are  frequently  attacked  by  rapid  and  exten- 
sive dental  caries.  Unless  their  mouths  be  vigorously  cared  for,  rich, 
sticky  carbohydrate  pabulum  is  adherent  to  the  teeth  and  fermentations 
are  high.  These  are  the  extreme  cases  of  carbohydrate  retention  to 
which  many  other  caries  susceptibles  who  ingest  considerable  quantities 
of  sugars  and  starches  approximate  to  a  less  degree,  especially  if  the 
mouth  hj'giene  is  poor.  In  all  of  these  the  quantity  of  food  retained 
in  the  mouth  furnishes  ample  material  for  lactic  acid  fermentations  and 
greatly  exceeds  any  possible  sugar  content  which  the  saliva  might 
possess.  These  retained  carbohydrates,  therefore,  seem  to  constitute 
a  direct  and  primary  factor  in  the  production  of  dental  caries,  for  they 
by  their  presence,  may  act  as  the  determining  cause  of  that  process. 
It  follows  that  all  the  measures  of  diet  selection  and  mouth  hygiene 
which  tend  to  reduce  the  sugar  pabulum  habitually  sticking  about 
the  teeth  will  have  a  direct  influence  upon  the  inception  and  progress 
of  dental  caries. 

Diets. — Sim  Wallace^  has  written  extensively  on  the  subject  of  diets 
and  their  relation  to  dental  caries.  He  believes  that  the  soft  and  pappy 
foods  which  constitute  the  bulk  of  diets  for  younger  children  are 
responsible  for  the  prevalence  of  dental  caries  during  the  early  years 
of  life.  Such  foods  require  little  mastication  and  tend  to  form  a  sticky 
carbohydrate  pabulum  about  the  teeth  favorable  to  lactic  acid  fermen- 
tation. Rather,  he  suggests  that  children  be  fed  hard  and  tough  foods 
which  afford  the  necessary  exercise  for  proper  development  of  the  jaws, 
stimulate  a  copious  flow  of  saliva  and  salivary  ferments  to  act  upon 
the  food  in  the  mouth,  scour  the  teeth  and  cleanse  them  from  food 
debris.  He  also  urges  that  the  amount  of  easily  fermentable  carbo- 
hydrates be  limited  and  followed  by  fresh  fruits,  preferably  apple,  or 
an  acid  food  or  drink  which  should  always  constitute  the  ending  of 
every  meal.  The  results  which  he  has  obtained  by  practical  applica- 
tion of  these  principles  in  the  diets  of  children  in  orphanages  and  in 
boarding  schools  have  convinced  him  of  their  efficacy  and  their  super- 
iority over  any  methods  of  artificial  prophylaxis.  In  view  of  the  data 
which  he  presents  he  claims^  "that  dental  caries  is  one  of  the  most 

1  Dental  Cosmos,  February,  1918,  et  seq. 

2  Prevention  of  Common  Diseases  of  Childhood,  1912. 

5  Wallace,  Sim:     Prevention  of  Dental  Caries,  Dental  Record,  1912. 


142  PREVENTIVE  DENTISTRY 

easily  and  certainly  preventable  of  diseases  and  there  would  seem  now 
no  valid  excuse  for  the  bringing  up  of  children  with  decayed  teeth." 

In  his  monumental  contribution  to  the  subject,  H.  P.  PickerilP  also 
treats  dental  caries  as  a  problem  of  dietetics.  In  many  respects  his 
conception  of  the  cause  and  control  of  dental  caries  is  similar  to  that  of 
Wallace,  but  it  differs  in  that  he  accentuates  the  importance  of  acid 
foods  and  fruits  in  the  diet  over  that  of  hard  and  tough  substances. 
Like  Wallace,  he  believes  that  the  occurrence  of  caries  is  dependent 
upon  the  ability  of  the  mouth  to  cleanse  itself  after  meals,  and  that 
caries  may  be  prevented  by  the  selection  of  a  diet  which  will  promote 
the  normal  cleansing  factors  of  the  mouth.  By  extensive  analyses  of 
the  saliva,  he  shows  a  variation  in  that  secretion  in  response  to  the 
stimulation  of  foods.  Dry  bread  increases  the  amount  of  saliva  2  to  1, 
and  apple  or  orange  increases  it  6  to  1 .  He  finds  that  all  acid  and  highly 
flavored  foods  increase  the  saliva  in  amount,  in  alkalinity,  and  in 
ptyaline  content,  all  three  of  which  are,  in  his  opinion,  important  in 
the  cleansing  of  the  mouth  and  the  prevention  of  dental  caries.  On  the 
other  hand,  bread  and  butter,  meat,  biscuits,  sugars,  tea,  milk  and" 
other  sapid  foods  are  either  neutral  or  depressant  in  salivary  stimulation. 
He  suggests  for  caries  control  that  all  diets  should  begin  and  end  with 
some  form  of  acid,  preferably  the  organic  or  fruit  acids;  that  sugars 
should  not  be  eaten  to  excess  and  should  always  be  incorporated  with 
some  form  of  acid ;  and  that,  so  far  as  possible,  the  diet  should  consist 
of  foods  having  a  high  flavor  and  acid  taste.  He  also  claims  that  alka- 
line dentifrices  have  a  depressant  effect  upon  the  secretions,  tending 
to  mouth  acidity,  and  suggests  the  use  of  acid  mouth  washes,  prefer- 
ably potassium  acid  tartrate,  0.50  per  cent.  The  author  reviews  the 
prevalence  of  dental  caries  among  the  various  nations  and  peoples  of 
the  world  and  states  that  among  civilized  races  the  susceptibility  to 
caries  is  high,  while  in  many  uncivilized  tribes  caries  susceptibility  is 
low;  that  the  diets  of  the  civilized  people  are  largely  unnatural,  sapid, 
and  low  in  acids,  while  those  of  the  uncivilized  people  are  composed  of 
natural  foods,  highly  flavored  and  acid;  and  that  caries  susceptibility 
is  not  due  to  civilization  per  se,  but  rather  to  the  adoption  of  a  civilized 
diet. 

The  views  of  Pickerill  have  been  concurred  in  by  Wm.  Gies  of  Colum- 
bia University  and  his  co-workers^  in  their  voluminous  contributions 
to  this  subject.  They  strongly  object  to  the  use  of  alkaline  dentifrices 
and  urge  the  adoption  of  acid  mouth  washes  as  a  means  of  caries  pre- 
vention. They  suggest  that  organic  acids  be  used  for  this  purpose, 
and  prefer  vinegar,  either  full  strength  or  diluted  claiming  that  it  dis- 

1  The  Prevention  of  Dental  Caries,  H.  P.  Pickerill,  1912. 

2  Jour.  All.  Dental  Soc,  1912,  p.  400;  1913,  p.  283  et  al. 


PERIDENTAL  AFFECTIONS  143 

organizes  the  mucoid  plaques  adherent  to  the  teeth  and  stimulates  a 
copious  flow  of  saliva,  thereby  decreasing  oral  fermentations  and  the 
tendency  to  dental  caries. 

It  is  not  practicable  to  discuss  fully  in  this  chapter  the  significance 
of  these  views  of  caries  prevention.  It  is  evident,  however,  even  from 
a  superficial  examination  that  most  authors  consider  the  prompt 
elimination  of  food  debris  from  the  mouth  and  the  attainment  of  oral 
cleanliness  as  matters  of  the  highest  importance  in  the  control  of  dental 
caries.  The  possibility  of  attaining  this  object  by  diet  alone  may  be 
determined  -only  by  a  wholesale  application  of  these  principles  to  a 
large  number  of  subjects  under  direct  observation.  That  hard  and 
coarse  foods  mechanically  cleanse  the  teeth  and  stimulate  an  active 
flow  of  saliva  to  wash  the  food  particles  from  the  mouth  is  a  well-known 
fact.  Consequently,  they  lessen  the  amount  of  carbohydrate  material 
about  the  teeth  and  reduce  lactic  acid  fermentation.  It  is  also  true 
that  acids  stimulate  the  salivary  secretions  in  amount  and  in  alkalinity 
and  have  a  tendency  to  leave  the  mouth  clean.  But  the  universal 
adoption  of  acid  diets  and  acid  mouth  washes  is  open  to  question. 
In  a  former  communication^  we  have  reported  certain  untoward  effects 
arising  from  the  use  of  acid  diets.  Patients  under  our  observation 
gave  evidence  of  pronounced  gastric  and  digestive  disturbances  while 
following  a  prescribed  acid  diet,  and  several  developed  a  severe  urticaria 
which  could  be  attributed  only  to  hyperacidity.  Others  were  found 
who  could  not  tolerate  acid  mouth  washes  as  their  teeth  became 
exceedingly  sensitive  to  slight  changes  in  temperature  during  their 
adoption.  Prinz  also  states^  as  his  opinion  that  the  correctness  of  the 
use  of  acid  mouth  washes  is  not  substantiated  by  clinical  experience, 
that  the  pharmacologic  principle  involved  in  the  selection  of  such  solu- 
tions is  erroneously  applied,  that  constant  forcible  stimulation  of  the 
salivary  glands  by  acids  is  followed  by  an  impairment  of  glandular 
function,  and  that  the  acidity  of  the  solution  kills  the  important  salivary 
ferments.  It  seems  wise,  therefore,  to  withhold  opinion  in  regard  to 
this  particular  procedure  until  further  scientific  data  have  been 
gathered.  It  is  possible  that  in  certain  selected  cases  where  the 
saliva  is  thick  and  mucinous  the  judicious  use  of  acids  in  the  diet  and 
acid  mouth  washes  may  have  a  beneficial  effect;  but  in  cases  of  thin, 
watery  salivas  with  a  tendency  toward  erosion  of  the  teeth,  it  seems  to 
us  that  acids  are  contra-indicated. 

Carl  Rose  looks  upon  dental  caries  as  a  form  of  physical  decadence 
and  degeneration  due  to  civiHzation.    The  uncivilized  man,  he  believes,^ 

1  Dental  Review,  1916,  p.  423. 

2  The  Therapeutic  Efficiency  of  Oral  Preparations,  Jour.  All.  Dental  Soc,  June,  1916. 

3  Dental  Cosmos,  1912,  p.  1214. 


144  PREVENTIVE  DENTISTRY 

has  better  teeth  and  less  dental  caries  as  a  result  of  the  laws  of  survival 
of  the  fittest  and  sexual  selection.  Only  those  having  good  dental 
organs  are  able  to  subsist  on  the  hard  and  tough  foods  which  compose 
their  diet.  The  primitive  male  chooses  a  mate  that  is  strong  physically 
and  has  sound  teeth,  and  the  children  which  result  from  such  union 
inherit  the  strong  physique  and  well  developed  dental  organs  of  both 
parents,  thus  continuing  the  race  of  caries  immunes.  Civilized  man. 
on  the  other  hand,  is  so  protected  by  law  that  physical  strength  is  not 
necessary  to  his  existence  and  the  character  of  his  food  does  not  require 
that  his  teeth  be  sound  or  in  a  high  state  of  efficiency.  Natural  selec- 
tion or  survival  of  the  fittest,  as  regards  physical  development  and 
dental  health  has  therefore  been  supplanted  among  civilized  races  by 
panmixia  and  survival  of  the  physically  unfit  resulting  in  a  general 
physical  deterioration,  one  phase  of  which  is  dental  defect  and  a  ten- 
dency to  dental  caries.  Rose,  accordingly,  looks  upon  the  prevalence 
of  dental  caries  among  civilized  peoples  as  a  problem  in  eugenics  and 
believes  that  the  remedy  may  be  found  only  in  the  intermarriage  of 
those  who  are  strong  in  body  and  perfect  as  to  dental  apparatus.  He 
naively  accuses  the  dental  profession  of  aiding  in  the  process  of  evolu- 
tionary decadence  of  the  teeth  by  so  repairing  and  replacing  decayed 
teeth  with  crowns  and  bridges  that  it  is  difficult  for  the  casual  observer 
to  determine  who  has  good  teeth  and  who  has  not.  The  views  of  the 
author  thus  expressed  are  interesting  and  worthy  of  consideration; 
but  the  means  of  control  of  dental  caries  which  he  suggests,  namely, 
the  regulation  of  intermarriage,  involves  weighty  problems  in  social 
economics  which  as  yet  are  unsolved,  and  their  application  on  a  large 
scale  at  the  present  time  is  impracticable. 

Rose  also  reports^  that  in  an  examination  of  a  large  number  of  school 
children  in  Germany,  it  was  very  evident  that  those  who  came  from 
sections  of  the  country  in  which  the  calcium  salts  of  the  water  and 
soils  were  high  had  better  formed  teeth  and  better  dental  health  than 
did  those  who  came  from  localities  in  which  the  calcium  salts  were  low. 
He  states  that  the  enamel  of  the  hard  and  resistant  varieties  of  teeth 
has  a  better  organization  and  contains  a  higher  percentage  of  calcium 
salts  than  does  that  of  the  softer  forms.  It  is  this  degree  of  organization 
and.  calcium  salt  content  that,  in  his  opinion,  renders  them  immune  to 
dental  caries.  In  view  of  this,  he  suggests  that  a  high  calcium  diet  be 
maintained  and  that  the  calcium  be  taken  in  the  form  of  natural  mineral 
waters  containing  calcium. 

The  latter  views  of  Rose  coincide  with  those  of  PickerilP  who  demon- 
strated that  the  enamels  of  soft  and  more  poorly  formed  teeth  were 

1  Monatschrift  f.  Zahnheilkunde  (abstract  in  Dental  Cosmos,  1909,  p.  135). 

2  Loc.  cit. 


PERIDENTAL  AFFECTIONS  145 

porous  and  contained  canals  which  ran  from  the  surfaces  of  the  enamel 
to  the  interior.  Enamels  of  hard  teeth  he  found  to  be  compact  and 
free  from  canals.  Also,  that  the  enamels  of  all  teeth  are  porous  at  the 
time  of  their  eruption,  and  that  in  time  the  enamel  surface  undergoes 
a  process  of  condensation.  In  some  mouths  the  enamel  becomes  hard, 
dense  and  sclerotic,  the  hard  tooth,  and  in  others  the  process  is  less 
complete,  the  tooth  enamel  is  soft  and  is  more  or  less  porous.  Pickerill 
states  as  his  opinion,  for  which  he  has  no  definite  proof,  that  the 
condensation  of  the  enamel  after  eruption  is  produced  by  infiltration 
of  calciimi  salts  from  the  saliva,  and  that  the  degree  of  condensation 
is  dependent  upon  the  degree  of  calcium  salt  concentration  in  the  saliva. 

In  former  contributions^  we  have  given  the  results  of  determinations 
made  of  the  calcium  in  a  large  number  of  salivas.  We  found  that  the 
saliva  of  every  individual  contained  a  definite  percentage  of  calcium 
which  remained  fairly  constant  in  amount  from  day  to  day.  Also, 
that  in  those  mouths  in  which  the  teeth  are  well  formed,  sound,  and 
free  from  dental  caries,  the  calcium  content  of  the  saliva  is  uniformly 
high;  while  in  those  cases  in  which  the  teeth  are  soft  and  carious,  the 
percentage  of  calcium  in  the  saliva  is  low.  So  definite  and  in^"a^iable 
were  the  findings  which  we  obtained  at  that  time  and  which  are  con- 
stantly being  corroborated  by  cases  selected  from  the  college  clinic, 
that  we  present  them  as  definite  proofs  of  the  view  that  the  quality  of 
the  enamel  and  tendency  of  the  teeth  to  caries  are  dependent  upon  the 
calcium  salt  content  of  the  salivas  which  bathe  them.  Of  all  the  other 
salivary  constituents  and  factors  which  have  been  suggested  as  caries 
controllers,  we  have  found  none  which  bear  so  close  and  definite  a 
relationship  to  clinical  conditions. 

We  have  fiu'ther  sho^A^l-  that  the  tooth  is  not  an  impermeable  sub- 
stance, but  that  salts  and  fluids  may  readily  pass  from  the  exterior  of 
the  enamel  through  its  substance  to  the  dentin  and  pulp;  and,  con- 
versely, from  the  pulp  through  the  dentin  and  enamel  according  to  the 
laws  of  osmotic  pressure.  This  being  true,  the  tooth  can  no  longer  be 
viewed  as  a  stable,  unchangeable  substance,  but  rather  as  one  that  is 
capable  of  being  built  up  and  condensed  by  salts  from  the  blood  and 
saliva  through  osmotic  interchange  of  these  fluids  through  the  tooth. 
It  is  obvious,  therefore,  that  in  accordance  with  the  laws  of  osmotic 
pressure  through  permeable  membranes,  the  degree  of  such  condensa- 
tion will  be  in  direct  relationship  to  the  salt  concentrations  in  the  blood 
and  the  saliva. 

In  om-  attempt  to  make  practical  application  of  these  theories  for 
the  prevention  of  dental  caries,  we  were  met  with  certain  difficulties. 

1  Bunting  and  Rickert:     Jour.  Nat.  Dent.  Assn.,  1912,  p.  287;  1917,  p.  81. 

2  The  Tooth,  a  Permeable  Membrane,  Jour.  Nat.  Dent.  Assn.,  1918,  p.  519. 
10 


146  PREVENTIVE  DENTISTRY 

Experimental  medicine  has  for  a  long  time  sought  means  by  which  it 
might  permanently  increase  the  calcium  salt  content  of  the  blood,  but 
as  yet  no  satisfactory  method  has  been  found.  We,  therefore,  in  our 
endeavor  to  raise  the  calcium  salts  of  the  saliva  by  forced  calcium 
feeding  and  stomachic  medication  were  confronted  with  the  same  diffi- 
culties. At  some  future  time,  when  the  process  of  calcium  metabolism 
shall  be  more  clearly  understood  and  methods  found  by  which  it  may 
be  raised,  we  may  be  able  to  increase  permanently  the  calcium  salt 
content  in  salivas  which  are  low  in  that  constituent  to  the  betterment 
of  the  teeth  and  the  reduction  of  dental  caries.  At  present  we  are 
limited  to  two  methods  of  procedure  in  such  cases,  namely,  the  selection 
of  diet  to  the  full  calcium  requirements  for  metabolism,  and  the  use  of 
mouth  washes  containing  calcium.  These  methods  we  have  employed 
on  selected  cases  for  some  time  with  seemingly  beneficial  results,  but 
sufficient  time  has  not  yet  elapsed  to  present  proofs  of  their  efficacy 
further  than  the  reasonableness  of  their  adoption. 

Viewing  thus  briefly  the  various  methods  of  caries  control  we  may 
ask  which  of  these  methods  are  worthy  of  adoption  to  meet  present- 
day  needs  and  in  what  manner  they  may  be  applied  by  the  general 
practitioner.  It  is  evident  that  in  dealing  with  caries  susceptibility, 
two  distinct  classes  of  causative  factors  present  themselves,  either  of 
which  may  act  singly  or  in  conjunction  with  the  other:  First,  those 
general  and  constitutional  disorders  which  favor  the  carious  process. 
For  example:  cases  of  nutritional  disturbance  resulting  in  poor  tooth 
formation  and  deficient  calcium  in  the  salivary  secretions;  cases  of 
increased  susceptibility  as  the  result  of  general  disease,  bodily  weakness, 
nervous  disorders  or  pregnancy;  and  those  cases  in  which  caries  has 
become  acute  following  a  change  in  habitat  or  climatic  conditions.  The 
second  class  of  factors  includes  those  which  are  local  and  oral,  namely, 
the  retention  of  food  in  certain  localities  of  the  mouth  by  irregularity 
of  the  teeth,  overhanging  fillings,  etc.;  a  general  excessive  accumulation 
of  carbohydrates  in  the  mouths  of  children,  millers,  candy  makers,  and 
those  having  habitually  unclean  mouths;  and  finally,  the  presence  in 
the  mouth  of  virulent  acid-forming  organisms.  It  will  be  seen  that 
these  two  classes  of  causative  factors  may  occur  in  an  almost  endless 
number  of  combinations,  making  the  analysis  of  every  case  an  extremely 
complicated  matter.  Also,  that  in  those  cases  in  which  the  first,  or 
constitutional  group  of  factors  predominates,  we  have  at  the  present 
time  little  means  of  control.  But  in  those  cases  in  which  the  second,  or 
local  factors  are  the  determining  ones,  definite  and  tangible  methods 
are  at  hand  by  which  we  may  reduce  the  virulence  of  attack  or  entirely 
prevent  it.  These  methods  are  all  those  which  make  for  continuous 
mouth  cleanliness  and  oral  hygiene. 


PERIDENTAL  AFFECTIONS  147 

The  field  of  oral  hygiene  is  a  broad  one.  In  its  practical  application 
the  greatest  benefits  as  regards  caries  control  are  to  be  obtained  during 
the  age  of  childhood.  As  the  deciduous  teeth,  one  by  one  are  lost  and 
are  replaced  by  their  permanent  successors,  the  food  has  a  tendency  to 
become  packed  and  retained  about  the  teeth  due  to  the  irregularities 
of  the  dental  arch,  oral  fermentations  are  high,  and  dental  caries  com- 
mon. The  enamels  of  newly  erupted  teeth,  not  having  been  condensed 
by  contact  with  the  saliva,  are  imperfect  and  at  this  time  are  least 
resistant  to  the  inception  of  caries.  Cavities,  when  once  begun,  grow 
rapidly  and  early  involve  the  pulp,  resulting  in  its  death  and  many 
times  in  severe  periapical  infection.  It  is  during  this  particularly 
susceptible  period  of  childhood  that  effective  measures  of  caries  control 
are  most  necessary;  for  could  we  conserve  the  teeth  of  children  and 
bring  them  to  manhood  and  womanhood  with  perfect  dentures,  we 
would  greatly  enhance  their  chances  for  maintaining  dental  health 
throughout  the  remainder  of  their  lives.  To  this  end  there  are  certain 
definite  and  obviously  effective  methods  of  procedure  by  which  the 
teeth  of  children  may  be  preserved.  These  methods  are  of  assured 
value  and  quite  apart  from  any  theories  or  speculations  regarding  caries 
control.  Although  these  measures  are  well  known  to  the  dental 
profession,  it  is  regrettable  that  a  great  many  practitioners  fail  to  put 
them  into  effect  because  of  the  fact  that  they  are  reluctant  to  operate 
on  children.  They  prefer  to  wait  until  their  little  patients  are  older, 
then  to  build  bridges  and  to  make  large  restorations  to  repair  as  best 
they  can  the  damage  that  has  been  done.  This  is  not  a  pleasant  or 
comforting  admission,  but,  unfortunately,  it  is  true. 

A  rational  method  of  oral  hygiene  for  children  might  be  outlined 
somewhat  as  follows:  children  should  be  seen  regularly  by  the 
family  dentist  for  the  purpose  of  assisting  and  encouraging  them  to 
keep  their  mouths  clean;  cavities  should  be  discovered  early  and  filled 
in  their  incipiency;  imperfect  sulci  on  bicuspids  and  molars  should  be 
protected ;  orthodontic  interference  should  be  given  whenever  indicated 
to  promote  normal  development  of  the  dental  arch;  children  should  be 
encouraged  to  include  in  their  diet  hard  foods  and  a  limited  amount  of 
sweets  combined  with  tart  and  acid  fruits;  special  emphasis  should  be 
given  to  the  foods  which  are  high  in  calcium,  as  milk,  butter-milk,  and 
cheese,  celery,  spinach,  turnips,  radishes,  string  beans  and  kidney  beans, 
cabbage,  cauliflower,  and  chard,  in  order  that  calcimn  metabolism 
may  be  amply  provided;  and,  finally,  the  frequent  use  of  lime  water 
as  a  mouth  wash  should  be  urged.  A  one-half  of  a  saturated  solution 
of  lime  water  seems  to  be  beneficial  as  it  increases  the  intra-oral  calcium 
content,  softens  the  plaques  about  the  teeth,  and  neutralizes  acids 
which  may  be  present. 


148  PREVENTIVE  DENTISTRY 

This,  or  a  similarly  efficient  regimen  of  mouth  hygiene,  for  children 
is  being  carried  out  most  completely  by  certain  dentists  who  have 
limited  their  practice  to  the  treatment  of  children.  In  this  manner 
they  are  bringing  their  patients  through  the  susceptible  age  of  child- 
hood to  maturity  with  a  complete  and  often  perfect  dental  apparatus. 
The  number  of  children  so  treated  is  comparatively  small,  but  it  is  an 
ever-increasing  one.  The  great  majority,  however,  must  be  cared  for  by 
the  general  practitioner  and  the  community  dental  clinic.  For  these  the 
task  is  colossal  and  may  be  accomplished  only  by  the  hearty  cooperation 
of  every  practitioner  in  the  attempt  to  do  his  part  in  caring  for  the 
children  under  his  supervision.  Could  this  work  be  performed  com- 
pletely, there  would  result  a  generation  of  people  who  would  require 
far  less  dental  attention  than  the  present  one  and  for  whom  the  problem 
of  dental  infection  and  its  attendant  systemic  involvement  would  be 
largely  solved. 

Passing  from  the  age  of  childhood  to  that  of  maturity,  we  find  a 
somewhat  different  set  of  conditions  presented  in  regard  to  caries 
control.  Usually  all  the  teeth  have  erupted  and  their  enamels  have 
become  more  or  less  condensed.  They  have  become  established  in  a 
certain  fixed  and  permanent  state  of  caries  susceptibility,  or  immunity, 
as  the  case  may  be,  dependent  upon  the  balance  of  forces  which  exist 
in  the  oral  environment.  It  is  true  that  individual  cases  may  change 
from  time  to  time  in  their  susceptibility  to  dental  caries  as  the  result 
of  changes  in  general  health  or  life  conditions,  but  it  is  well  known  that 
the  majority  may  be  classified  as  belonging  to  certain  definite  types  of 
virulence.  For  the  relief  of  those  cases  which  have  a  tendency  toward 
dental  caries,  we  are  limited  for  the  present  to  those  measures  which 
will  most  effectually  eliminate  or  reduce  the  carbohydrates  and  fer- 
mentations which  are  essential  to  the  carious  process.  Could  we  but 
keep  the  teeth  continuously  free  from  these,  dental  caries  could  not 
exist.  But  mouth  cleanliness  is  at  best  but  a  relative  matter  for  lactic- 
acid  fermentations  undoubtedly  do  exist  in  all  mouths  to  a  greater  or 
less  degree.  Our  only  hope,  therefore,  in  oral  prophylaxis  is  to  reduce 
these  fermentations  to  the  point  where  the  other  protective  forces  of 
the  mouth  will  establish  caries  immunity.  It  must  be  admitted  that 
the  complete  elimination  of  caries  in  every  case  by  oral  prophylaxis  is 
impossible;  for,  in  certain  mouths  the  forces  of  caries  susceptibility 
are  very  strong  and  the  protective  powers  correspondingly  weak. 
Fortunately,  it  is  also  true  that  a  very  large  percentage  of  susceptible 
cases  may  be  made  practically  immune  and  the  severe  types  reduced 
in  virulence  by  the  rational  application  of  prophylactic  measures. 
After  viewing  the  work  of  many  operators  who  are  practicing  preventive 
dentistry  most  intensively,  the  author  personally  applied  the  principles 


PREVENTION  OF  PYORRHEA  ALV SOLARIS  149 

of  prophylaxis  to  a  group  of  patients  to  substantiate  or  disprove  the 
claims  which  were  made  as  to  the  efficacy  of  such  measures.  These 
patients  had  been  mider  personal  observation  for  some  time  and  many 
of  them  had  been  strongly  susceptible  to  dental  caries  for  years.  In 
several  cases  so  treated,  dental  caries  has  not  occurred  during  the  past 
four  years,  although  previous  to  that  time  cavities  appeared  \\'ith 
frequent  regularity.  Others  showed  a  marked  decrease,  having  but 
two  or  three  cavities  diuing  that  time.  One  particularly  suscept- 
ible case  was  immune  for  three  years  and  then  suddenly  became 
susceptible  coincident  ^^'ith  a  protracted  illness  and  general  debility. 
The  results  obtained  from  this  limited  number  of  cases  have  clearly 
demonstrated  that  a  regimen  of  strict  oral  prophylaxis  does  limit,  and 
in  many  cases^  controls  the  occurrence  of  dental  caries. 

THE  PREVENTION  OF  PYORRHEA  ALVEOLARIS. 

In  a  succeeding  chapter  which  -^tII  be  devoted  to  that  subject,  the 
history  of  our  present  knowledge  of  the  disease  commonly  knoT\Ti  as 
pyorrhea  alveolaris  and  the  various  causative  factors  wliich  are  con- 
nected \\dth  the  process  "^ill  be  set  forth  in  detail.  By  a  careful  perusal 
of  the  matter  there  presented  it  "^-ill  be  seen  that  the  author,  after 
having  reviewed  all  the  important  theories  and  speculations  thereto, 
concludes  that  pyorrhea  is  a  distinctly  infectious  process  acting  in 
conjunction  -^-ith  a  lowering  of  local  tissue  resistance.  That  is,  the 
process  consists  in  a  progressive  destruction  of  the  tissues  about  the 
teeth  by  infectious  organisms  resulting  in  the  formation  of  characteristic 
pyorrhetic  pockets.  But  these  infectious  organisms  do  not  produce 
their  characteristic  results  upon  the  tissues  unless  the  natural  resist- 
ance of  these  tissues  against  infections  has  been  destroyed  by  some 
form  of  injury  or  disturbance  of  circulation  and  metabolism.  It 
follows,  that  although  the  disease  is  essentially  an  active  infective 
process  the  determining  factor  in  every  case  consists  in  one  or  more 
predisposing  causes  which  lower  the  resistance  of  the  local  tissues  and 
make  the  infective  invasion  possible.  Fiu-ther,  it  may  logically  be 
inferred  that  if  the  peridental  tissues  could  be  protected  from  injury 
and  kept  in  health  and  normal  resistance,  pyorrhea  would  most 
effectually  be  prevented.  At  the  present  time  of  all  the  methods  which 
have  been  suggested  for  the  prevention  of  peridental  diseases  those 
measures  which  have  been  directed  toward  the  maintenance  of  health 
and  normal  resistance  m  the  gums  and  gingi^'al  tissues  ha^'e  yielded 
the  most  beneficial  results. 

It  has  been  pointed  out  previously  that  the  mucous  membrane 
of  the  oral  cavity  normally  possesses   a  high  degree   of  resistance 


150  PREVENTIVE  DENTISTRY 

against  infections.  But,  when  the  gingival  tissues  are  disturbed  either 
by  local  irritations  or  by  systemic  fault  of  metabolism,  gingivitis  is  set 
up,  the  gingival  tissues  lose  their  normal  tone  and  fall  away  from  the 
necks  of  the  teeth.  In  this  manner  the  gingival  crevice  is  opened  and 
an  opportunity  is  offered  for  the  entrance  and  growth  of  oral  micro- 
organisms, which  process  constitutes  the  first  step  in  the  great  majority 
of  cases  of  incipient  pyorrhea.  In  general,  the  local  causes  of  gingivitis 
consist  of  various  traumatic  injuries,  as  the  impaction  of  food,  encroach- 
ment of  calculus,  overhanging  fillings,  crowns  and  bridges,  and  exces- 
sive stresses  upon  the  teeth  due  to  malocclusions;  chemical  injuries  as 
persistent  localized  growths  of  bacteria  about  the  necks  of  the  teeth 
which  continually  irritate  the  gingival  tissues;  and  certain  other  special 
local  irritants.  The  general  or  constitutional  causes  of  gingivitis 
consist  of  circulatory  poisons  such  as  lead,  mercury,  etc.,  or  of  general 
disturbances  of  circulation  and  nutrition  by  which  the  metabolism  of 
the  local  tissues  is  altered.  Of  these  two  types  of  injury  the  local 
causes  are  in  the  majority.  Indeed,  it  may  be  seen  in  clinical  practice 
that  when  all  local  irritations  are  removed  and  the  circulation  of  the  " 
peridental  tissues  is  stimulated  by  proper  massage,  the  gingival  tissues, 
as  a  rule,  may  be  restored  to  health  and  maintained  in  that  state  even 
in  the  presence  of  evident  general  and  systemic  disturbances. 

The  practice  of  preventive  dentistry  as  regards  the  control  of  peri- 
dental disease,  therefore  should  consist  of  the  thorough  prophylactic 
removal  of  all  local  irritants  and  other  injurious  influences  from  the 
teeth  and  the  peridental  tissues.  This  should  be  accompanied  by  the 
correction,  so  far  as  possible,  of  all  systemic  faults  and  the  stimulation 
of  the  circulation  in  the  peridental  tissues.  By  a  rational  application 
of  these  measures  it  will  be  discovered  that  gingivitis  is  the  most  easily 
and  certainly  preventable  of  all  dental  diseases.  And  it  also  follows 
that  in  preventing  gingival  disturbance  and  by  maintaining  the  health 
and  normal  resistive  powers  of  these  tissues,  the  great  majority,  if  not 
all  of  the  more  serious  peridental  diseases  are  effectually  prevented. 

In  all  of  the  foregoing  it  will  be  seen  that  as  we  survey  the  whole  field 
of  preventive  dentistry,  and  the  methods  of  procedure  which  thus  far 
have  been  suggested  for  the  control  of  the  two  most  important  diseases, 
namely,  dental  caries  and  pyorrhea  alveolaris,  oral  prophylaxis  in  its 
broadest  application  offers  the  greatest  hope  of  success.  Not  that 
these  measures  are  presented  as  an  infallible  panacea  for  dental  ills, 
but  that  the  faithful  performance  of  those  local  procedures  which 
make  for  oral  and  dental  health  constitutes  the  most  reasonable  and 
practical  method  of  at  least  partial  prevention  with  which  we  at  this 
time  may  combat  dental  disease.  The  efficacy  of  this  form  of  practice 
has  been  demonstrated  clearly  by  a  large  group  of  operators  who  have 


ORAL  PROPHYLAXIS  151 

intensively  applied  the  principles  of  oral  prophylaxis  to  a  large  number 
of  patients  with  the  result  that  for  them  dental  and  oral  diseases  have 
been  largely  eliminated.  These  same  procedures  as  outlined  in  the 
following  section  may  well  be  adopted  in  a  modified  form  by  every 
dental  practitioner. 

ORAL  PROPHYLAXIS. 

The  term  prophylaxis  has  been  widely  applied  in  dentistry  to  the 
operation  of  cleaning  the  teeth;  so  much  so  that  in  the  minds  of  many 
it  has  come  to  be  synonymous  with  that  procedure.  In  its  broadest 
sense,  however,  oral  prophylaxis  consists  of  not  only  cleaning,  the 
teeth,  but  also  includes  all  measures  which  tend  to  protect  the  mouth 
tissues  from  disease,  and  make  for  dental  and  oral  health.  Oral 
prophylaxis  therefore  embraces  all  methods  by  which  the  various 
harmful  influences  may  be  removed  from  the  dental  and  peridental 
tissues,  and  the  tissues  left  in  such  condition  that  a  continual  mainte- 
nance of  oral  cleanliness  and  oral  health  is  possible. 

In  general,  the  practice  of  oral  prophylaxis  in  a  broad  sense  consists 
of  the  following  procedures: 

1.  Removal  of  all  calcareous  deposits,  stains  and  other  extraneous 
substances  from  the  teeth. 

2.  Smoothing  and  polishing  of  all  exposed  tooth  surfaces  and  rough 
fillings. 

3.  Detection  and  filling  of  all  cavities. 

4.  Restoration  of  faulty  proximate  contacts  and  tooth  contours. 

5.  Removal  of  overhanging  portions  of  fillings,  crowns,  bridges,  etc. 

6.  Relief  of  undue  stresses  on  the  teeth. 

7.  Protection  or  filling  of  defective  sulci. 

8.  Instruction  of  the  patient  as  to  daily  personal  care. 

9.  Sustained  periodic  supervision  and  assistance. 

It  will  be  seen  that  all  of  the  above  procedures  are  directed  toward 
the  removal  of  irritating  and  harmful  influences  from  the  teeth  and 
surrounding  tissues  and  the  establishment  of  oral  conditions  in  which 
the  mouth  will  be  practically  self-cleansing,  or  capable  of  being 
cleansed  by  the  personal  efforts  of  the  patient.  The  question  has 
often  been  raised  as  to  the  need  of  such  prophylactic  measures  and 
the  possibility  that  in  their  performance  actual  harm  may  be  done. 
Objection  has  been  made  to  polishing  the  tooth  surfaces  on  the  ground 
that  the  enamel  would  thereby  be  thinned  and  weakened  and  that 
this  operation  could  not  be  accomplished  without  doing  irreparable 
damage  to  the  peridental  tissues.  It  is  undoubtedly  true  that  as  the 
result  of  many  overzealous  and  radical  exponents  of  this  form  of 
practice,  an  excessive  amount  of  enamel  substance  has  been  removed 


152  PREVENTIVE  DENTISTRY 

from  the  teeth  and  extensive  injury  to  the  peridental  tissues  produced. 
But  these  distressing  and  unwarranted  procedures  which  have  been 
done  in  the  name  of  oral  prophylaxis  cannot  be  construed  as  a  real 
objection  to  that  process  when  safely  and  sanely  performed.  Upon 
careful  examination  it  will  be  seen  that  in  a  large  percentage  of  mouths 
the  teeth  are  more  or  less  incrusted  with  salivary  calculi  which  act  as 
irritants  to  the  peridental  tissues  and  by  virtue  of  the  rough  surfaces 
which  they  present  tend  to  mechanically  hold  food  in  contact  with  the 
teeth  and  gums.  On  those  tooth  sm-faces  which  are  not  so  incrusted 
it  will  be  seen  that  the  enamel  is  frequently  dull  and  rough,  lacking 
the  -natural  luster  which  it  normally  should  possess.  Tooth  surfaces 
of  both  classes  offer  considerable  retention  for  food  and  bacterial 
plaques;  and  cannot  be  cleansed  by  natural  forces  or  the  personal 
efforts  of  the  patient.  The  great  prevalence  of  the  roughened  enamel 
surfaces  to  be  found  in  the  mouths  of  the  great  majority  of  people 
is  evidently  due  in  part  to  the  soft  and  pappy  diets  which  are  almost 
universally  adopted  today  by  the  civilized  world.  In  the  primitive 
and  uncivilized  races  we  find  teeth  with  highly  polished  enamel  surfaces 
and  a  marked  freedom  from  dental  disease.  Among  these  people  the 
diet  contains  more  gritty  and  hard  foods  which  in  the  act  of  mastication 
produce  considerable  mechanical  cleansing  and  polishing  of  the  enamel 
surfaces.  Moreover,  many  races  that  are  noted  for  the  brilliance  and 
lustre  of  their  teeth  are  known  to  spend  considerable  time  each  day 
rubbing  the  surfaces  of  their  teeth  with  various  roots  and  herbs  which 
cleanse  and  polish  them.  It  follows  therefore  that  those  who  live  upon 
foods  that  tend  to  stick  to  the  teeth  rather  than  scour  and  cleanse 
them,  must  substitute  some  artificial  mechanical  measures  for  the 
natural  action  of  the  food  if  they  would  have  clean  and  healthy  mouths. 
As  a  rule,  the  indifferent  and  irregular  habits  of  personal  dental  care 
on  the  part  of  the  patient  are  not  sufficient  to  compensate  for  the  lack 
of  friction  which  the  hard  and  gritty  foods  would  give.  Consequently, 
in  the  great  majority  of  mouths  concretions  form  on  those  portions  of 
the  teeth  which  receive  the  least  friction  and  the  enamel  surfaces  which 
are  continuously  covered  by  bacterial  films  and  plaques  become 
etched  and  roughened  by  acids  which  are  formed  on  the  spot.  For 
these  it  is  evident  that  the  first  step  in  oral  prophylaxis  should  be  the 
removal  of  concretions  and  the  subsequent  polishing  of  all  tooth  surfaces 
to  the  end  that  the  patient  may  cleanse  the  teeth  properly  by  his 
personal  efforts.  It  is  true  that  in  some  mouths  the  teeth  are  naturally 
polished  and  clean.  In  such  cases  it  will  be  found  that  the  salivary 
secretions  are  thin  and  low  in  mucin,  while  the  teeth  are  frequently 
abraded  giving  evidence  of  heavy  and  thorough  mastication.  From 
this  we  see  that  in  them  the  tendency  for  lodgement  of  food  and  calculi 


ORAL  PROPHYLAXIS 


153 


upon  the  teeth  is  sHght  and  the  natural  friction  of  mastication  is  marked. 
As  a  result,  the  mouth  is  naturally  self-cleansing  and  as  a  rule  free  from 
disease.  This  t}^e  is,  however,  in  the  great  minority  while  the  rough- 
ened and  incrusted  denture  is  much  more  common. 

It  follows,  therefore,  that  the  great  majority  of  our  patients  need 
assistance  in  the  care  of  their  mouths.  They  need  careful  and  thorough 
operative  procedures  to  remove  all  forms  of  irritation  from  the  dental 
and  peridental  tissues,  and  to  eliminate  all  mechanical  hindrances  to 
oral  cleanliness.  Unless  this  be  done,  oral  cleanliness  is  impossible  in 
the  mouth  of  the  average  patient. 

1.  Removal  of  Concretions  from  the  Teeth. — Calcareous  deposits 
on  the  exposed  sm'faces  of  the  teeth  form  masses  which  are  more  or 
less  evident  and  may  be  recognized  easily  (Fig.  88) .   For  their  removal 


■j^H 

^mmmuMjg^imH^^m^gm^  ^- 

■  '  1  ^ 

•  W^  ^w 

! 

*" 

■M^'  ^ 

Fig.  88. — Salivary  calculi. 


a  large  variety  of  instruments  have  been  suggested,  scalers,  cleaners, 
files,  planes,  chisels,  etc.,  among  which  considerable  latitude  for  the 
personal  preference  of  the  operator  may  be  exercised.  The  chief 
requisite  of  each  is  that  by  their  use  the  deposits  may  be  effectually  and 
completely  removed  and  that  the  enamel  siu-face  will  not  be  scratched 
or  injured  in  the  operation.  Calculi  which  are  formed  on  the  roots  of 
the  teeth  beneath  the  free  margin  of  the  gum  are  much  more  difficult 
to  remove.  As  a  rule,  they  are  entirely  covered  by  the  gum  tissues, 
are  hidden  from  view,  and  may  be  detected  only  by  an  instrumental 
exploration  of  the  subgingival  crevice.  Certain  forms  are  fine  and 
granular  while  others  consist  of  thin  and  plate-like  scales  firmly 
adherent  to  the  surfaces  of  the  root  (Fig.  89)  both  of  which  may  be 
overlooked  and  are  difficult  of  removal  when  discovered. 


154 


PREVENTIVE  DENTISTRY 


In  the  removal  of  dental  calculi,  especially  the  subgingival  varieties, 
too  much  stress  cannot  be  placed  upon  the  means  of  discovering  and 
locating  these  deposits.  Since  they  are  frequently  hidden  from  view, 
the  mouth  mirror  as  a  means  of  diagnosis  cannot  be  relied  upon. 
Therefore,  the  operator  must  cultivate  a  keen  sense  of  touch  by  which 
he  may  read  the  character  of  the  enamel  and  cementum  surfaces  by 
passing  the  point  of  an  explorer  or  other  instrument  over  them.  In 
this  manner  he  may  judge  as  to  the  roughness  or  smoothness  of  these 
surfaces  and  may  detect  all  deposits  and  concretions  which  may  be 
attached  to  them.  To  this  end  it  is  desirable  that  the  operator  culti- 
vate the  habit  of  grasping  and  using  the  instrument  after  the  manner 


Fig.  89. — Subginlval  calculi. 


of  holding  the  pen  in  the  old  Spencerian  style  of  writing  (Figs  90 
and  91). 

If  the  instrument  be  held  lightly  with  the  muscles  of  the  hand  at 
ease  and  uncramped,  the  vibrations  which  are  set  up  as  the  point  is 
passed  over  various  rough  and  smooth  surfaces  will  be  transmitted  to 
the  hand  and  will  accurately  portray  the  character  of  these  surfaces. 
For  instance,  one  may  try  the  experiment  of  passing  an  instrument 
held  in  this  manner  over  the  surfaces  of  etched  and  smooth  glass  and 
may  easily  distinguish  one  from  the  other  by  the  feel  or  vibrations  of  the 
instrument.  If,  on  the  contrary,  the  instrument  be  held  tightly  and 
considerable  force  continually  exerted  upon  it,  the  muscles  of  the  hand 
soon  become  cramped  and  the  keen  sense  of  touch  is  lost, 


DUAL  PROPHYLAXIS 


155 


It  is  equall}'  important  tluit  in  all  forms  of  prophylactic  instrumenta- 
tion the  same  Spencerian  type  of  hand  grasp  should  be  maintained  and 


Fig.  90. — Method  of  lidldinji  instrument. 


the  fingers  should  remain  as  nearly  passive  as  is  possible.     If  they  are 
continually  flexed  and  extended  for  the  purpose  of  moving  the  instru- 


FiG.  91. — Method  of  holding  instrument. 


ment  over  the  surface  of  the  tooth,  the  sense  of  relationship  is  lost,  and 
as  a  result  of  continued  muscular  effort  the  fingers  become  cramped 


156 


PREVENTIVE  DENTISTRY 


and  the  tactile  sense  is  dulled.  Rather  should  the  instrument  be 
actuated  by  a  rocking  motion  of  the  whole  hand  describing  the  arc 
of  a  circle  about  the  tip  of  the  second  or  third  finger  which  rests  upon 
some  fixed  point  in  the  mouth  as  shown  in  Fig.  91 .  This  is  accomplished 
by  flexion  of  the  wrist  or  elbow  by  which  the  instrument  may  be  made 
to  traverse  the  surface  of  the  tooth  in  any  desired  direction  without 
any  effort  of  the  fingers  other  than  to  lightly  hold  the  instrument  in 
position.  If  this  method  be  adopted  the  operator  may  feel  the  sur- 
faces of  the  tooth  above  and  below  the  gum  margins  searching  for 
extraneous  deposits  and  when  he  has  found  them  he  may,  by  the 
momentary  exertion  of  pressure,  pry  off  the  foreign  body  and  continue 
to  smooth  the  tooth  surfaces  until  by  the  sense  of  touch  through  the 
instrument  he  knows  that  the  deposit  is  entirely  removed.  In  this 
manner  he  may  operate  for  hours  still  maintaining  his  keen  sense  of 
touch  and  the  free  use  of  his  hand. 


Z  3  4 

Fig.  92. — Tompkins'  scalers. 


In  the  selection  of  instruments  adapted  to  the  practice  of  oral  prophy- 
laxis the  average  practitioner  may  be  easily  confused  by  the  wide  range 
of  types  which  are  offered  by  the  dental  supply  houses  and  private 
individuals.  Leaving  out  of  account  the  many  clumsy  and  crude  forms 
which  have  no  place  in  preventive  dentistry,  there  are  in  common  use 
today  four  basic  types  of  prophylactic  instruments,  namely,  Tompkins' 
scalers  and  Younger' s  scalers,  files,  and  planes. 

The  Tompkins'  scalers  (Fig.  92)  consist  of  variously  shaped  instru- 
ments, having  aright  angle  turn  at  their  extreme  end.  They  are  intended 
to  be  used  with  a  pull  motion  by  which  they  may  be  hooked  over  a 
calcareous  deposit  and  remove  it.  This  type  of  instrument  has  been 
widely  accepted  and  has  been  adopted  in  a  modified  form  in  the 
Buckley,  Logan  and  Adair  sets.  The  chief  objections  to  them  are  that 
they  are  not  adapted  to  smoothing  the  enamel  or  cementum  after  the 
removal  of  the  calculi,  and  in  the  hands  of  the  inexperienced  operator 


ORAL  PROPHYLAXIS 


157 


considerable  damage  may  be  done  to  the  tooth  surfaces  by  the  sharp 
corners  of  the  blade. 

The  Younger  type  of  scalers  (Fig.  93)  is  made  in  the  form  of  slender 
elongated  spoons,  the  shanks  of  which  are  bent  at  various  angles  to 
reach  the  several  surfaces  of  the  teeth.  These  are  also  intended  to  be 
used  with  a  pull  motion,  the  instrument  being  so  tipped  that  the 


^^=^/==^ 


3  4-  5      6 

Fig.  93. — Younger's  scalers. 


lateral  edge  of  the  blade  is  presented  to  the  surfaces  of  the  tooth  at  an 
acute  angle.  In  this  manner  the  blade  may  be  slipped  down  beneath 
the  gum  margin  at  a  right  angle  to  the  long  axis  of  the  tooth  and  by  a 
drawing  motion  the  surfaces  of  the  tooth  may  be  cleansed  and  smoothed 
without  injury  to  the  soft  tissues  (Fig.  94) .  This  type  of  instrument  has 


Fig.  94. — Younger's  scaler,  enlarged. 


a  wide  range  of  usefulness  and  probably  is  the  safest  and  most  efficient 
type  in  the  hands  of  inexperienced  operators. 

Files  of  various  shapes,  sizes  and  fineness  of  cut  have  been  extensively 
used  in  prophylaxis.  D.  D.  Smith  made  use  of  a  selection  of  fine  and 
coarse  files  (Fig.  95) ,  the  shanks  of  which  were  bent  at  various  angles. 
A  somewhat  different  set  of  coarse  files  has  been  suggested  by  Towner 


158 


PREVENTIVE  DENTISTRY 


(Fig.  96),  which  are  very  effective  in  removing  calcuh  and  smoothing 
roughened  enamel  and  cementum.  When  sharp,  the  file  is  rapid  in  its 
action  and  covers  a  greater  surface  with  each  stroke  than  other  forms  of 
instruments.  In  many  respects  it  is  the  most  universal  in  its  applica- 
tion and  the  easiest  to  master.  The  chief  objection  to  this  form  of 
instrument  is  that  its  broad  surface  does  not  give  the  delicate  sense  of 
touch  that  is  obtained  by  a  smaller  blade  and  as  a  result  the  operator 


II  U  13  14-  15  16 


Fig.  95.— D.  D.  Smith's  files. 

may  easily  be  deceived  regarding  the  character  of  the  tooth  surfaces, 
either  leaving  upon  them  thin  plates  of  calculi  or  cutting  too  deeply  into 
the  enamel  or  cementum. 

The  planing  form  of  instrument  (Fig.  98) ,  as  designed  by  Carr,  James 
and  Hartzell,  constitutes  a  special  and  distinct  type.  These  sets  are 
composed  of  150  different  instruments  nearly  all  of  which  have  a  right 
angle  turn  at  their  extreme  tip.     The  blade  is  much  heavier  than 


Fig.  96. — ^Towner's  files. 


that  of  the  Tompkins  type  and  is  so  made  that  it  has  a  relatively 
broad  and  flat  surface  on  the  extreme  end  of  the  right  angle  tip 
which  is  intended  to  ride  upon  the  surface  of  the  tooth  when  in  use. 
The  shanks  are  so  shaped  that  when  the  flat  5nd  is  laid  upon  the  tooth 
and  the  shank  rests  upon  some  other  surface  of  the  tooth,  the  inner 
edge  of  the  blade  acts  after  the  manner  of  a  draw  plane  or  scraper  when 
pulled  over  the  surface  of  the  tooth  (Fig.  98) .    When  used  in  this 


ORAL  PROPHYLAXIS 


159 


manner  these  instruments  will  roi:iove  all  foreign  and  extraneous 
substances  from  the  enamel  and  cementum  and  by  continued  applica- 
tion will  shave  or  plane  down  these  surfaces  until  they  are  smooth. 
The  large  number  of  instruments  in  the  set  are  arranged  in  groups  of 


Fig.  97. — Planing  instruments. 

eight  which  are  so  shaped  that  they  readily  adapt  themselves  to  eight 
positions  on  the  tooth.  The  various  sets  of  eight  instruments  are  then 
grouped  according  to  curvature  of  shanks,  straight,  convex  and  con- 
cave; according  to  size,  small,  medium  and  large;  and  according  to 
angle  of  inclination  of  shank  to  handle,  namely  narrow  and  Made  angle. 
The  principle  upon  which  these  planes  are  built  and  their  wide  adapta- 


FiG.  98. — Plane  in  positic  n  in  tooth,  enlarged. 


bility  to  reach  all  tooth  and  root  surfaces  make  them  in  the  hands  of  the 
skilled  operator  the  most  efficient  of  the  available  prophylactic  instru- 
ments. On  the  other  hand,  it  is  true  that  the  technic  of  using  these 
complicated  sets  of  planes  is  not'easily  or  quickly  mastered  and  may  be 


160  PREVENTIVE  DENTISTRY 

successfully  accomplished  by  only  those  operators  who  give  consider- 
able attention  to  this  method  of  practice.  They  therefore  are  not  to 
be  recommended  to  the  general  practitioner  who  gives  but  a  small  part 
of  his  time  and  attention  to  dental  prophylaxis.  Rather  should  he 
adopt  some  of  the  simpler  forms  of  instruments,  to  begin  with  at  least, 
and  master  their  use  to  the  best  of  his  ability.  With  the  Younger 
type  of  instrument  combined  with  files  and  small  delicate  sickles 
valuable  and  gratifying  results  may  be  obtained. 

As  has  been  said,  the  selection  of  instruments  is  more  or  less  a  per- 
sonal matter.  It  is  not  so  important  that  one  particular  type  be 
selected,  as  that  some  suitable  set  be  adopted  and  mastered  by  the 
operator  so  that  he  may  completely  remove  all  extraneous  deposits 
from  the  teeth.  This  may  be  successfully  accomplished  in  a  large 
percentage  of  cases  by  any  of  the  above  types  of  instruments. 

Stains. — ^The  great  majority  of  stains  on  the  teeth  are  extraneous  to 
the  enamel,  being  glued  to  the  surface  by  mucoid  films.  It  follows 
therefore  that  when  all  such  films  and  deposits  are  removed  from  the 
teeth,  the  stains  will  also  be  eliminated.  This  may  be  accomplished 
by  instrumentation  alone  or  by  the  subsequent  polishing  of  the  tooth 
surfaces.  Many  of  the  nostrums  which  are  recommended  for  the 
quick  and  ready  removal  of  stains  are  dangerous  and  should  be  avoided. 
They  are  frequently  highly  acid  in  reaction  and  depend  upon  a  super- 
ficial decalcification  of  the  enamel  surface  to  release  the  stain.  These 
highly  acid  preparations,  therefore,  etch  and  destroy  the  natural 
enamel  surface  and  frequently  accomplish  considerable  damage  as  a 
result  of  their  use. 

For  a  discussion  of  the  handling  of  stains  which  have  penetrated  the 
substance  of  the  tooth  or  have  diffused  outward  from  the  pulp,  the 
reader  is  referred  to  Chapter  XL 

Plaques  and  Films. — The  various  forms  of  mucinous  and  bacterial 
plaques  which  cover  all  neglected  and  unclean  surfaces  of  the  teeth 
are  of  as  great  importance  as,  if  not  greater  than,  the  dental  calculi. 
It  is  in  these  films  that  the  salivary  calculi  and  stains  first  become 
impregnated  and  are  attached  to  the  surface  of  the  tooth.  So  also  do 
they  afford  an  excellent  medium  for  the  propagation  of  oral  micro- 
organisms, many  of  which  when  growing  in  this  manner,  exert  a  harmful 
influence  upon  the  teeth  and  surrounding  tissues.  For  instance,  acid- 
producing  bacteria  beneath  a  plaque  may  produce  sufficient  acid  to 
decalcify  the  enamel  and  form  an  initial  lesion  of  caries.  Other  types 
of  organisms  when  growing  in  a  plaque  contiguous  to  the  gums  at  the 
neck  of  the  tooth  frequently  exert  a.  toxic  and  irritative  effect  upon 
these  tissues,  producing  chronic  gingivitis  and  a  tendency  toward 
pyorrhea.     It  is  therefore  highfy  essential  that  all  plaques  and  films 


ORAL  PROPHYLAXIS  161 

be  removed  from  the  teeth  by  prophylactic  measures  and  the  patient 
taught  to  prevent  their  recurrence  by  daily  personal  care. 

When  these  films  are  infiltrated  with  stains  or  calcareous  deposits 
they  may  be  recognized  easily,  but  when  they  do  not  contain  these 
products  they  are  colorless  and  invisible  to  the  eye.  In  many  instances 
they  may  be  detected  by  the  particular  injury  which  they  produce  or 
by  the  employment  of  a  stain  which  will  reveal  their  location  and 
distribution.  For  this  purpose  a  disclosing  solution  which  has  been 
suggested  by  Skinner  is  very  valuable.    The  formula  is  as  follows: 

lodin  (crystals) 50  grains 

Potassium  iodid 15       " 

Zinc  iodid 15       " 

Glycerin 4  drams 

Aqua 4       " 

If  this  stain  be  applied  to  the  surfaces  of  the  teeth  and  washed  off 
with  a  stream  of  water,  all  films  and  plaques  will  be  highly  colored  by 
the  iodin  and  will  stand  out  in  bold  relief  to  the  clean  portions  of  the 
teeth  which  will  be  clear.  This,  or  some  other,  efficient  disclosing 
solution  should  be  used  in  the  diagnosis  of  every  case  and  in  the 
beginning  and  the  close  of  all  prophylactic  treatments.  In  this 
manner  the  plaques  may  be  located  to  the  end  that  in  the  subsequent 
polishing  of  the  tooth  special  attention  may  be  given  to  their  removal. 

2.  Smoothing  and  Polishing  Tooth  Surfaces  and  Fillings. — ^When 
all  deposits  have  been  removed  from  the  teeth,  the  surfaces  of  the 
enamel  and  cementum  should  be  smoothed  and  polished.  Much  of 
this  may  be  done  with  the  same  instrument  with  which  the  calculi  are 
removed  by  simply  continuing  to  plane  the  tooth  surfaces  after  they 
are  cleaned  until  they  feel  smooth  and  free  from  irregularities.  Occa- 
sionally the  enamel  surfaces  are  so  rough  and  corrugated  that  the 
ordinary  scalers  and  files  are  not  sufficient  to  smooth  them.  Especially 
is  this  true  of  the  enamel  in  the  region  of  the  gingival  line  which  is 
frequently  pitted  and  roughened  by  the  action  of  acids  produced  by 
cervical  fermentations.  These  may  be  smoothed  by  planing  instru- 
ments or  by  the  judicious  use  of  stones  and  discs.  When  the  enamel 
has  been  made  smooth  in  this  manner,  it  should  be  polished  with  XXX 
Silex^  or  with  combinations  of  these  two  substances  followed  by  tin 
oxid.  This  may  be  done  with  orange  wood  sticks  and  porte  polishers 
(Fig.  100),  vigorously  rubbing  all  accessible  enamel  surfaces  until  a  high 
polish  has  been  obtained.  The  interproximate  surfaces  are  reached  by 
thin  tapes  and  the  wide  floss  carrying  the  polishing  powder,  care  being 
taken  to  prevent  injury  of  the  interproximate  gum  tissues.  This  process 

1  XXX   Silex   may    be  obtained   from   the   Bridgeport   Wood   Finishing    Company, 
Bridgeport,  Conn. 
11 


162 


PREVENTIVE  DENTISTRY 


may  be  expedited  by  substituting  an  engine  polisher  for   the  hand 
rubbing.     For  this  purpose  the  common  bell-shaped  rubber  cup  should 


Fig.  99. — Orange-wood  stick  and  porte  polishers. 

never  be  used  as  it  invariably  injures  the  gingival  tissues.     There  are 
however,  two  types  of  rubber  cups,  namely,  the  Young  B.  S.  polisher 


Fig.  100. — B.  S.  polishers. 


(Fig.  101).  and  the  Davis  Polishing  cup  (Fig.  102),  which  are  so  shaped 
that  they  may  be  adapted  to  the  labial  and  lingual  surfaces  of  practically 


Fig.  101. — Davis  polishing  cup. 


all  teeth  and  if  used  with  care  will  do  no  injury  to  the  gingival  tissues. 
By  the  use  of  this  form  of  polisher  together  with  soft  felt  wheels,  a 


ORAL  PROPHYLAXIS 


m: 


smooth  and  highly  lustrous  polish  may  be  given  to  the  labial  and  lingual 
enamel  surfaces  in  a  comparatively  short  time. 

In  the  process  of  polishing  enamel  surfaces  it  should  be  borne  in 
mind  that  the  enamel  covering  of  the  teeth  is  a  highly  important 
structure  and  should  not  be  sacrificed  ruthlessly.  We  have  shown 
elsewhere^  that  the  outer  surface  of  well  formed  enamel  is  more  dense 
and  impervious  to  fluids  than  a  cut  enamel  surface  can  be  made  by  any 
form  of  polishing  (Fig.  102).  It  is  undesirable,  therefore,  to  reduce  the 
surfaces  of  those  enamels  which  are  naturally  lustrous  and  polished. 
And  those  that  are  dull  and  rough  should  be  smoothed  and  polished 
with  the  least  iiossihle  loss  of  enamel  surface.    This  may  be  accomplished 


Fig.  102. — Section  of  tooth  showing  portion  of  enamel  at  {A)  which  had  been  ground 
and  polished,  the  normal  enamel  surface  being  shown  at  (5) .  The  tooth  was  immersed 
in  silver  nitrate  after  polishing  and  by  a  comparison  of  the  depth  to  which  the  stain 
has  penetrated  the  enamel  it  will  be  seen  that  the  ground  and  polished  portion  {A)  is 
more  porous  than  the  natural  surface  {B). 


usually  by  the  removal  of  a  layer  of  enamel  not  greater  than  the  thick- 
ness of  writing  paper.  When  the  teeth  are  polished  in  this  manner 
with  due  regard  for  the  conservation  of  enamel  substance,  no  harm  will 
result  to  the  dental  tissues  and  an  inestimable  benefit  to  oral  hygiene 
may  be  accomplished  (Figs.  103  and  104). 

Care  should  be  exercised  to  prevent  the  injury  of  the  peridental 
tissues  in  the  process  of  tooth  polishing.  The  heroic  measures  which 
are  practiced  by  over-enthusiastic  exponents  of  preventive  dentistry, 
such  as  the  ruthless  cutting  of  the  gingival  and  interproximate  gum 
tissues  and  the  vigorous  sawing  between  the  teeth  in  the  act  of  polishing 

1  Bunting  and  Rickprt:     Jour,  Nat,  Dent.  Assn.,  January,  1917,  p.  90, 


164  PREVENTIVE  DENTISTRY 

the  enamel  surfaces,  are  unwarranted  and  unnecessary.  The  teeth 
may  be  made  sufficiently  smooth  to  be  self-cleansing  and  oral  hygiene 
may  be  established  by  much  more  conservative  measures  than  these 
without  any  attendant  injury  to  the  peridental  tissues. 


Fig.  103. — Upper  cuspid  before  and  after  polishing  for  five  minutes  in  the  manner 

described  in  the  text. 

All  fillings  should  be  polished  and  made  absolutely  flush  with  the 
tooth  surfaces.  A  rough  cervical  filling  may  often  act  as  a  nidus  for 
the  attachment  of  a  bacterial  plaque  which  may  promptly  reappear 
after  a  prophylactic  treatment.  When  the  filling  is  made  perfectly 
smooth  and  polished,  these  surfaces  may  be  kept  clean  and  free  from 
localized  fermentation. 


Fig.  104. — Upper  molar  before  and  after  polishing  for  five  minutes  in  the  manner 
described  in  the  text. 

3.  Detection  and  Filling  of  All  Cavities. — ^At  this  stage  of  the  process 
careful  search  should  be  made  for  carious  lesions  in  the  teeth  and  all 
necessary  operative  procedures  should  be  performed.  Indeed,  the 
early  detection  and  treatment  of  these  defects  should  always  be  a 
matter  of  prime  importance  in  preventive  dentistry.  It  is  the  small 
cavity  which  is  most  successfully  handled  and,  if  taken  early,  the 
treatment  is  not  complicated  by  pulp  disturbances  and  devitalization. 


Oral  prophylaxis 


165 


4.  Restoration  of  Faulty  Proximate  Contacts  and  Contours. — Faults 
in  form  and  contour  of  teeth  are  very  prolific  causes  of  peridental 
irritation  and  disease.  When  proximate  cavities  are  repaired  by 
fillings  which  are  not  sufficiently  contoured  to  afford  a  normal  contact 
with  the  adjacent  tooth,  food  is  crowded  between  the  teeth  in  mastica- 
tion and  as  a  result  the  interproximate  gum  tissue  (Fig.  105)/  is  severely 
injured.  Normally  these  tissues  are  protected  by  tight  contacts  which 
in  mastication  tend  to  deflect  the  food  labially  and  lingually  and  all 
proximate  fillings  should  be  made  to  reproduce  these  normal  inter- 
proximate relationships.  The  importance  of  this  procedure  cannot  be 
too  strongly  emphasized  since  those  who  have  studied  these  conditions 
have  recognized  that  open  and  faulty  contacts  constitute  the  point 


Fig.   105. — Models  showing  the  injury  to  gum  tissues  arising  from  the  lack  of  proper 
interproximate  contact. 

of  inception  of  a  very  large  percentage  of  peridental  infection.  Opera- 
tive dentistry,  therefore,  to  be  consistent  with  the  principles  of  oral 
hygiene,  must  be  so  constructed  that  all  proximate  contours  will  be 
restored  and  the  normal  relationships  of  the  teeth  to  each  other 
reestablished. 

It  is  equally  important  that  the  buccal  and  lingual  contours  be 
restored  to  the  full  normal  curvature.  A  comparison  of  the  normal 
contours  of  teeth  will  reveal  the  fact  that  certain  types  possess  far 
more  buccal  and  lingual  contour  than  others  (Fig.  106).  It  is  also 
evident  that  when  these  contours  are  pronounced,  the  buccal  and 
lingual  gum  tissues  are  protected  from  the  injury  from  excursions  of 


1  Friesell,  H.  E.:     The  Dental  Items  of  Interest,  1918,  p.  977. 


166 


PREVENTIVE  DENTISTRY 


food  against  them  during  mastication.  But  in  case  the  contours  are 
fiat,  considerable  damage  may  be  done  to  the  gingival  tissues  by  the 
impaction  of  food  during  mastication.  Instance  of  this  may  be  seen 
in  Fig.  107  in  which  it  will  be  noted  that  the  gingival  margin  about  the 


Fig.  106. — Types  of  teeth  showing  natviral  variance  in  buccal  and  labial  contours. 


ORAL  PROPHYLAXIS 


167 


lower  central  incisor  has  been  torn  and  caused  to  recede,  by  virtue  of 
the  fact  that  the  tooth  in  question  was  flat  on  its  labial  surface  and 
did  not  protect  the  gingivae.  A  correction  of  this  natural  fault  may  be 
made  by  the  introduction  of  bulging  cervical  inlays  which  will  afford 


Fig.  107. — Retraction  of  labial  gum  tissues  about  lower  central  incisor  resulting  from 
excursions  of  food  over  fiat  labial  surface  of  the  incisor. 

artificial  food  deflectors.  Perhaps  the  worst  offender  in  this  respect 
is  the  straight  sided  type  of  crown  about  which  the  gingival  tissues 
are  constantly  in  a  state  of  irritation.  In  contrast  to  these,  we  find 
that  properly  shaped  and  adapted  crowns  as  in  Fig.  109  protect  the 
labial  and  lingual  tissues  and  cause  a  minimum  amount  of  irritation. 


Fig.  1 


5.  Removal  of  All  Overhanging  Portions  of  Fillings,  Crowns,  Bridges, 
etc. — ^Fillings  which  are  not  flush  with  the  tooth  surfaces,  and  cro^^^lS 
which  are  not  closely  adapted  to  the  teeth  at  the  cervical  region  offer 
considerable  retention  for  food  and  infectious  materials  and  constitute 


168 


PREVENTIVE  DENTISTRY 


potent  predisposing  factors  in  both  caries  and  peridental  disease. 
So  frequent  are  these  operative  faults  that  scarcely  a  case  is  presented 
which  does  not  have  one  or  more  of  them.  In  the  practice  of  preventive 
dentistry  it  is  necessary,  therefore,  not  only  to  conform  all  new  restora- 
tions to  these  principles,  but  also  to  correct  the  faults  of  all  operative 
procedures  which  have  previously  been  made,  even  if  it  involves  their 
removal  and  replacement.  It  frequently  happens,  however,  that  by 
the  judicious  use  of  files  and  chisels  a  faulty  filling  may  be  reshaped 
and  made  to  conform  very  closely  to  the  normal  contours  of  the  tooth. 
So,  also,  overhanging  edges  of  porcelain  crowns  may  often  be  reduced 
by  small  pointed  stones  and  made  flush  with  the  end  of  the  root.  By 
these  procedures  such  faulty  restorations  may  cease  to  be  a  menace 
and  may  be  retained  for  many  years  of  service. 


>i*~; 

i 

.  r 

Fig.  109. 


-Traumatic  occlusion,  upper  right  cuspid  being  forced  outward  and  distally 
by  undue  stresses  arising  from  the  loss  of  molar  occlusion. 


6.  Relief  of  Undue  Stresses. — It  has  been  noted  by  operators  who 
have  studied  peridental  diseases  that  many  cases  of  pyorrhea  begin 
about  teeth  upon  which  there  has  been  excessive  and  unusual  stress. 
In  such  cases  it  will  be  seen  that  when  the  jaws  are  brought  into 
occlusion,  these  teeth  are  moved  laterally  in  their  sockets  by  the  gliding 
of  the  inclined  planes  of  opposing  teeth,  one  upon  the  other.  This  is 
noted  frequently  in  the  upper  anterior  teeth  when  because  of  the  loss 
of  a  large  proportion  of  the  molars  and  bicuspids,  the  bite  has  closed 
and  the  lower  incisors  strike  against  the  lingual  surfaces  of  the  upper 
incisors  to  produce  a  pronounced  traimaatic  injury.  As  a  result,  the 
peridental  attachments  on  the  lingual  surfaces  of  the  roots  of  these 
teeth  are  broken  down,  the  teeth  become  loosened  and  drift  labially 
until  they  elevate  the  upper  lip  and  in  extreme  cases  assume  a  position 
practically  perpendicular  to  their  original  inclination  (Fig.  109).  It  is 
of  the  greatest  importance  that  all  such  cases  of  excessive  incisal 


ORAL  PROPHYLAXIS  169 

occlusion  be  discovered  early  before  serious  damage  and  protrusion  of 
the  teeth  have  been  accomplished,  as  the  correction  of  these  faults 
and  restoration  of  the  teeth  to  their  normal  position  are  extremely 
difficult  and  as  a  rule  impracticable.  The  treatment  of  such  cases 
consists  of  either  raising  the  bite  by  the  insertion  of  mechanical  appli- 
ances to  restore  missing  posterior  teeth  or  the  shortening  of  the  lower 
incisors  by  grinding  until  they  no  longer  strike  the  opposing  teeth. 

Traumatic  occlusion  may  produce  injury  in  the  peridental  tissues 
about  teeth  other  than  the  incisors.  Fig.  Ill  is  taken  from  a  mouth 
which  had  slight  indications  of  pyorrhea  save  that  of  a  deep  pocket  on 
the  mesial  of  the  upper  right  first  molar  and  the  distal  of  the  adjacent 
second  bicuspid.     It  will  be  noted  that  the  lower  first  molar  had  been 


4^^ 

^t  ■' 

HHtai 

j| 

^ 

II 

1 

H^..^*^.. 

l| 

■ 

Itaaa^ 

^^■^ 

Fig.  110. — Deep  pyorrhetic  pockets  on  mesial  of  first  molar  and  second  bicuspid  upper 
due  to  traumatic  occlusion  of  lower  second  molar. 

extracted  some  time  previously  and  the  lower  second  molar  was  striking 
the  upper  first  molar  at  an  unusual  angle.  The  traumatism  thus  occa- 
sioned, associated  with  a  general  lowering  of  tissue  resistance,  of  which 
there  was  evidence  in  this  patient,  resulted  in  a  serious  pyorrhetic 
involvement  of  the  teeth  under  stress.  Numerous  examples  of  injiu"y 
from  occlusal  stress  are  to  be  found  in  susceptible  individuals  when  the 
cusps  of  the  molars  and  bicuspids  are  high  and  closely  interlock  in 
occlusion.  In  them  it  is  found  that  the  teeth  stand  in  such  a  position 
that  as  they  are  brought  together  in  rest  the  cuspal  planes  do  not 
immediately  fit,  but  that  two  inclined  surfaces  first  strike  together  and 
then  slide  into  position  producing  a  lateral  shearing  strain  upon  both 
teeth.    Unless  the  resistance  of  the  peridental  tissues  is  exceedingly 


170  PREVENTIVE  DENTISTRY 

high  peridental  injury  and  degeneration  result  which  are  very  frequent 
causes  of  pyorrhetic  affections. 

In  oral  prophylaxis,  therefore,  the  mouth  should  be  examined  for 
all  undue  stresses,  especially  when  the  cusps  of  the  teeth  are  high  and 
closely  interlocked.  And  in  all  operative  procedures  which  involve 
the  reproduction  of  tooth  form,  such  as  fillings,  crowns,  bridges,  etc., 
it  is  highly  important  that  they  be  so  shaped  that  no  unnatural  or 
unusual  stresses  be  exerted  by  them  upon  the  opposing  teeth.  Many 
teeth  have  been  loosened  by  an  over-full  filling  and  many  a  bridge 
which  was  otherwise  technically  perfect  has  failed  because  of  faults  of 
occlusion,  which  have  resulted  in  traumatic  injury  and  loss  of  attach- 
ment of  the  peridental  tissues  about  the  abutments.  So  also,  may 
prosthetic  appliances  produce  injury  to  the  peridental  tissues  by  exces- 
sive pressure  upon  the  soft  tissues  and  lateral  stress  upon  the  teeth.  It 
is  only  by  a  full  appreciation  of  these  factors  and  a  close  study  of  the 
stresses  in  each  individual  case  that  preventive  dentistry  may  success- 
fully be  accomplished. 

7.  Protection  of  Sulci. — It  is  a  matter  of  common  observation  that 
the  sulci  of  many  teeth  are  attacked  by  caries  very  early.  Especially 
is  this  true  in  the  case  of  those  teeth  which  have  high  cusps  and  corres- 
pondingly deep  and  more  or  less  patent  sulci.  In  these  occlusal  crevices 
food  and  acid-producing  bacteria  are  retained  under  very  favorable 
conditions  for  the  inception  of  dental  caries.  Prophylactic  measures 
directed  toward  the  protection  of  these  extremely  vulnerable  areas 
in  the  tooth  consist  of  the  cleansing  of  the  sulci  with  picks  and  explorers, 
dessication  and  fiooding  with  copper  cement,  or  other  suitable  sub- 
stance. In  this  manner  the  defect  in  the  tooth  will  be  filled  by  a 
material  that  will  exert  a  continued  antiseptic  and  germicidal  action, 
in  its  immediate  vicinity  and  will  effectually  protect  the  tissues  against 
caries  invasion  for  a  considerable  length  of  time.  This  form  of  treat- 
ment is  especially  beneficial  in  cases  of  children's  teeth,  if  performed 
immediately  after  the  eruption  of  the  tooth  before  the  carious  process 
has  set  in. 

8.  Instructions  to  the  Patient. — As  we  read  the  various  opinions  upon 
the  subject  we  find  that  a  wide  range  of  procedures  is  suggested  by 
dental  practitioners  to  their  patients  as  to  the  personal  care  of  the 
mouth.  All  agree  that  the  daily  personal  attention  to  the  cleansing 
of  the  mouth  and  teeth  is  a  matter  of  highest  importance  in  preventive 
dentistry.  The  most  that  may  be  done  by  the  operator  is  to  so  organize 
the  mouth  that  dental  cleanliness  is  made  possible  and  then  the  future 
course  of  the  case  is  determined  largely  by  the  manner  in  which  the 
patient  cooperates  in  maintaining  oral  cleanliness.  Obviously  patients 
should  first  be  given  definite  instructions  as  to  the  method  by  which 


ORAL  PROPHYLAXIS  171 

they  should  cleanse  then"  mouths,  but  as  yet  no  uniform  technic  of 
personal  care  has  been  agreed  upon.  Differences  of  opinion  have  been 
expressed  as  to  the  armamentarium  to  be  used,  some  preferring  one 
style  of  brush  and  others  another  style.  Mobile  a  few  have  objected  to 
the  use  of  any  kind  of  a  brush  on  the  ground  that  they  believe  them  all 
to  be  harmful  to  the  oral  tissues  and  suggest  in  their  place  the  use  of 
cotton  rolls  and  swabs.  The  majority,  however,  agree  that  some  form 
of  brush  and  flat  floss  should  be  employed  although  the  manner  of  their 
use  is  not  generally  agreed  upon.  So  also  is  there  variance  of  opinion 
regarding  the  form  of  dentifrice  that  should  be  adopted,  individual 
preference  ranging  through  the  whole  gamut  of  powders,  pastes,  and 
dental  lotions.  The  most  comprehensive  statement  of  the  views  of 
leading  workers  in  preventive  dentistry  was  obtained  by  the  Editor  of 
the  Items  of  Interest  and  was  published  in  the  ]May  issue  of  that  journal 
for  1915.  In  answer  to  a  letter  relative  to  the  instruction  which  should 
be  given  to  patients,  a  variety  of  opinions  and  statements  were  received 
which  were  compiled  into  a  symposium  upon  that  subject.  To  this 
the  reader  is  referred  for  a  general  view  of  what  are  perhaps  the  most 
sane  and  conservative  lines  of  thought  on  this  subject.  It  is  not 
possible  to  discuss  in  this  place  all  these  various  views,  but  rather  a 
particular  course  of  procedure  will  be  outlined  which  is  selected  from 
various  sovu"ces  and  which  seems  to  the  author  to  be  well  founded. 
These  views  are  suggested,  not  as  measiues  par  excellence,  nor  as  views 
possessing  any  special  virtue,  for  it  is  true  that  each  of  the  various 
operators  is  daily  accomplishing  excellent  results  in  the  mouths  of 
patients  by  the  use  of  the  particular  method  of  oral  prophylaxis  T\^hich 
he  advocates,  but  rather  are  these  measures  stated  as  a  simple  workable 
basis  which  may  be  taught  easily  to  the  patient  and  which  has  yielded 
very  beneficial  results  under  the  personal  supervision  of  the  author. 

It  must  be  recognized  at  the  outset  that  the  purpose  of  brushing  the 
mouth  and  teeth  is  two-fold;  first,  the  cleansing  of  the  oral  cavity  of 
all  food  and  bacterial  plaques;  second,  the  production  of  mechanical 
friction  upon  the  peridental  gum  tissues  which  mil  stimulate  the  cir- 
culation and  harden  and  toughen  the  epithelium  to  the  point  that  it 
becomes  highly  resistant  to  mechanical  injm-y.  To  accomplish  these 
ends  not  only  the  teeth  but  the  gums  as  well  should  be  brushed 
vigorously  with  a  hard  stiff-bristled  brush  used  in  the  proper  manner. 

Brushes. — Diuing  recent  years  the  matter  of  obtaining  suitable 
brushes  has  been  a  difficult  one,  due  to  the  fact  that  the  war  has  inter- 
fered with  the  importation  of  the  best  brushes  and  materials  for  making 
them.  As  a  result,  at  the  present  time,  there  are  on  the  market  two 
forms  which  are  acceptable,  one  the  Rolling  Brush  (Fig.  112)  and  the 
other  a  brush  designed  by  Dr.  Card,  of  Philadelphia  (Fig.  114).   These 


172  PREVENTIVE  DENTISTRY 

brushes  are  said  to  be  made  from  the  bristles  of  the  Russian  boar,  and, 
as  a  rule,  wear  very  well.  They  are  made  of  three  grades  of  bristles, 
soft,  medium  and  hard,  of  which  the  hard  is  usually  to  be  preferred. 


Fig.  111. — The  Rolling  brushes. 


In  the  selection  of  a  brush,  the  largest  size  that  can  comfortably  be 
adapted  to  the  mouth  of  the  patient  should  be  chosen.  The  largest 
size  of  these  two  forms  may  be  used  in  the  average  adult  mouth,  while 
the  smaller  forms  are  well  suited  to  small  mouths  and  those  of  children. 


Fig.  112. — Dr.  Card's  brushes. 

The  method  of  using  the  brush  should  consist  of  two  general  types 
of  motion.  The  first  is  a  sweeping  stroke  beginning  on  the  gums  and 
continuing  over  the  teeth  in  a  direction  parallel  with  the  long  axis  of 
the  teeth,  down  on  the  uppers,  and  up  on  the  lowers.  The  brush  is 
placed  on  the  buccal  surface  of  the  upper  jaws  with  the  bristles  pointing 
up  and  the  side  of  the  brush  lying  against  the  teeth.  By  a  rotary 
motion  of  the  hand  the  bristles  are  made  to  sweep  down  over  the  gums 


ORAL  PROPHYLAXIS 


173 


and  the  teeth,  m  a  vigorous  manner,  thereby  stimulating  the  gingival 
circulation  and  cleansing  the  buccal  and  a  portion  of  the  proximate 
surfaces  of  the  teeth  (Fig.  113).  On  the  lingual  a  similar  motion  is 
used  while  on  the  lower  a  reverse  motion  is  employed,  namely,  a 
sweeping  upstroke  on  the  gums  and  the  teeth. 

To  reach  the  cervical  portion  of  the  tooth  and  embrasures  a  special 
stroke  is  used.  This  is  accomphshed  in  case  of  the  upper  teeth,  by 
placing  the  brush  with  its  side  against  the  upper  jaw  with  the  bristles 


Fig.  113. — Two  views  of  downward  stroke. 


pointing  down  in  a  position  exactly  the  reverse  of  the  first  described 
method  (Fig.  114).  The  brush  is  then  carried  %^%  down  over  the 
teeth  in  a  lengthwise,  shaving  stroke  so  that  the  inner  row  of  bristles 
will  be  forced  gently  into  the  interproximate  spaces  and  against  the 
cervical  portion  of  the  buccal  surfaces.  By  repeated  motions  of  this 
order  those  portions  of  the  teeth  which  receive  the  least  friction  by  the 
first  method  are  rubbed  and  cleansed.  This  may  be  accomplished  by 
the  use  of  the  single  row  Rolling  brush  and  by  the  larger  multi-row 


174 


PREVENTIVE  DENTISTRY 


brushes  used  in  the  same  manner,  one  row  of  bristles  only  being  made 
operative.  On  the  lower  jaw  the  same  motion  is  used  in  a  reverse 
manner.     For  the  lingual  surfaces  a  peculiarly  shaped  brush  has  been 


Fig.  114. — Two  \dews  of  interdental  stroke. 


Fig,  115, — The  single  row  Rolling  brush  (above)  and  the  Barnes  lingual  brush 

(below) . 


ORAL  PROPHYLAXIS 


175 


suggested/  which  may  be  made  from  any  celluloid-handled  brush. 
The  head  of  the  brush  is  cut  off  removing  all  but  two  rows  of  bristles 
together  with  that  portion  of  the  celluloid  handle  which  holds  them. 
The  celluloid  handle  is  then  softened  in  boiling  water  and  bent  to  the 
shape  shown  in  Fig.  116.  With  this  brush  the  patient  may  effectually 
cleanse  a  large  portion  of  the  lingual  surfaces  and  the  lingual  embra- 
sures, by  a  gentle  shaving  stroke. 

Dental  Floss. — It  should  be  obvious  that  by  no  method  of  brushing 
may  the  entire  mesial  and  distal  surfaces  of  teeth  in  close  contact  be 
reached.  For  cleansing  these  surfaces  of  the  teeth  which  are  so  fre- 
quently attacked  by  dental  caries,  it  is  necessary  that  the  patient  be 
taught  to  pass  the  flat  floss  into  each  interproximate  space  to  wipe  off 
the  two  proximate  surfaces.  For  this  purpose  the  fiat  dental  floss  is 
much  to  be  preferred  over  the  round  cord  as  it  covers  more  surface  and  is 
more  effective  as  a  cleanser  of  the  teeth  (Fig.  116).     In  this  operation 


Fig.  116. — Flat  dental  floss. 

great  care  should  be  exercised  to  prevent  the  snapping  of  the  cord  against 
the  interproximate  gum  septa  for  in  this  manner  an  over-zealous  or 
careless  patient  may  do  serious  harm  to  the  soft  tissues.  The  floss, 
therefore,  should  be  held  with  the  fingers  of  the  two  hands,  exposing 
but  a  short  segment  of  the  cord  and  by  a  gentle  sawing  motion  it  should 
be  carried  beyond  the  point  of  contact  (Fig.  117).  Then  the  mesial  and 
distal  surfaces  should  be  gently  and  carefully  wdped  to  rid  them  of 
food  and  bacterial  plaques,  but  in  no  case  should  the  floss  be  sawed 
or  manipulated  in  a  rough  or  vigorous  manner.  If  ordinary  care  is 
used  in  the  instruction  of  the  patient  this  procedure  will  do  no  harm 
to  the  gum  tissues  but,  on  the  contrary,  will  serve  as  an  active  and 
effective  means  of  combating  interproximate  caries  and  gingivitis. 

Dentifrices. — ^The  question  of  dentifrices  is  one  about  which  there 
has  been  considerable  discussion.  At  the  present  time,  however,  there 
is  little  accurate  information  on  this  subject.     For  the  most  part,  the 


Dr.  Henry  Barnes,  Clevel9.nd 


176 


PREVENTIVE  DENTISTRY 


dental  profession  has  depended  upon,  and  recommended,  the  various 
dental  preparations  which  have  been  placed  on  the  market  and  widely 
advertised  without  any  definite  knowledge  of  the  ingredients  of  which 


Fig.  1 17. — Carrying  dental  floss  between  the  teeth. 


Fig.  118. — Passing  floss  over  mesial  surface  of  bicuspid. 


they  are  composed  or  the  action  which  they  exert  when  used.  In  a 
former  communication^  we  published  microphotographs  showing  the 
shape  and  character  of  the  grits  contained  in  a  number  of  the  popular 
dentifrices.     At  that  time  we  called  attention  to  the  fact  that  certain 

1  Bunting  and  Rickert:     Jour.  Nat.  Dent.  Assn.,  August,  1915,  p.  247. 


ORAL  PROPHYLAXIS  111 

of  these  preparations  are  highly  abrasive  and  rapidly  cut  the  enamel 
especially  when  a  crosswise  stroke  of  the  brush  is  used.  On  the  other 
hand,  many  contained  almost  no  abrasive  materials  and  were  exceed- 
ingly bland  in  their  action. 

It  is  the  opinion  of  the  author  that  no  one  dentifrice  should  be 
invariably  adopted.  Rather  should  a  type  of  preparation  be  selected 
which  is  best  adapted  to  each  individual  case.  In  the  preparation  of  a 
mouth  for  preventive  dentistry,  a  strongly  abrasive  dentifrice  may  be 
prescribed  which  will  assist  materially  in  smoothing  the  tooth  sm-faces 
and  in  ridding  the  mouth  of  fermentation.  When  the  mouth  is  under 
control,  it  will  be  found  that  oral  cleanliness  may  be  accomplished  by 
less  harsh  measures.  Then  the  patient  may  be  given  a  smoother 
preparation  by  which  he  can  maintain  the  tooth  surfaces  in  a  highly 
polished  and  clean  state.  Occasionally  cases  are  presented  in  which 
the  viscosity  of  the  oral  fluids  tends  to  make  the  cleansing  of  the  mouth 
so  difficult  that  the  bland  dentifrices  are  inadequate.  For  them  a 
coarser  preparation  should  be  prescribed  to  be  used  either  alone  or 
alternately  with  the  finer  form.  In  all  such  cases  special  supervision 
should  be  given  to  see  that  damage  to  the  tooth  and  peridental  tissues 
does  not  occur  as  a  result  of  the  abrasive  action  of  the  dentifrice. 

As  to  the  various  dental  lotions  and  mouth  washes  which  are  on  the 
market,  it  is  the  opinion  of  the  author  that  none  of  them  possess  very 
essential  therapeutic  action  and  all  of  them  are  of  doubtful  value. 
Occasionally,  when  considerable  hypertrophy  of  the  soft  tissue  has 
taken  place,  the  zinc  chlorid  preparations,  as  Astringosol  and  Lavoris, 
may  be  used  for  a  short  time  to  assist  in  reducing  the  inflammation, 
but  as  soon  as  this  has  been  accomplished  they  should  be  discontinued. 
It  must  be  remembered  also  that  these  preparations  are  impotent 
when  used  alone  and  act  only  as  simple  adjuvants  to  the  necessary 
operative  and  surgical  measures  by  which  the  local  irritants  must  be 
removed  before  the  swelling  and  inflammation  may  be  reduced.  If  a 
dental  lotion  is  desired,  a  5  per  cent,  salt  solution  or  a  one-half  satiu^a- 
tion  of  lime  water  may  be  used  to  good  advantage.  The  salt  solution 
seems  to  act  as  a  tonic  to  the  gum  tissues  as  well  as  a  detergent  to  cleanse 
the  teeth.  The  lime  water,  although  not  so  palatable,  is  useful  in  that 
it  softens  the  mucinous  plaques  and  by  its  alkalinity  tends  to  neutralize 
any  acids  which  may  be  present. 

9.  Sustaining  Supervision. — ^\Vhen  a  mouth  has  been  reorganized  as  has 
been  outlined  and  the  patient  has  learned  how  to  care  for  it  properly, 
a  complete  change  in  the  oral  picture  will  be  noted.  Instead  of  the 
fermentations  and  general  uncleanliness  which  previously  had  existed, 
the  teeth  appear  clean  and  polished  and  the  giuns  are  hard  and  firmly 
resistant.  If  the  patient  continues  to  perform  the  dut}^  of  daily  cleans- 
ing, the  mouth  will  remain  in  this  improved  state  of  oral  hygiene.  But, 
12 


178  PREVENTIVE  DENTISTRY 

as  a  rule,  even  the  most  careful  cooperation  on  the  part  of  the  patient 
is  not  sufficient  to  reach  all  the  siufaces  of  the  teeth  and  gums  and  in 
time  there  will  be  fresh  collections  of  food,  bacterial  plaques  and  other 
concretions  in  those  localities  which  have  received  the  least  care.  For 
the  permanent  maintenance  of  oral  hygiene  and  preventive  dentistry, 
it  is  necessary  that  the  patient  be  seen  occasionally  for  the  purpose  of 
assisting  him  in  the  care  of  those  most  difficult  places,  to  note  and 
correct  any  beginning  gingivitis  and  to  discover  any  new  cavities  which 
may  have  appeared.  To  this  end  simple  measures  of  prophylaxis  are 
necessary  which  may  be  accomplished  in  from  twenty  to  thirty  minutes. 
They  should  consist  of  the  exploration  of  the  cervical  areas  and  gingival 
crevices  with  a  small  Younger  type  instrument  searching  for  and  remov- 
ing all  accretions.  The  surfaces  of  the  teeth  may  then  be  lightly 
gone  over  with  the  engine  cup  and  one  of  the  abrasive  dental  pastes 
followed  by  the  use  of  the  dental  floss  upon  the  proximate  surfaces. 
This,  with  a  direction  of  the  attention  of  the  patient  to  certain  places 
in  the  mouth  which  need  special  care  is  all  that  usually  is  necessary. 
The  frequency  of  these  sustaining  treatments  should  be  determined  by 
the  nature  of  the  case.  Some  will  need  to  be  seen  once  each  month 
while  others  may  safely  be  allowed  to  go  two  and  three  months  without 
attention  by  the  operator. 

From  the  necessarily  lengthy  detailed  description  of  this  programme 
of  preventive  dentistry,  the  reader  may  be  led  to  think  that  the  per- 
formance of  these  measures  is  a  long  and  tedious  process.  In  cases 
which  require  considerable  reorganization  of  fillings,  crowns,  bridges^ 
etc.,  it  is  true  that  considerable  time  may  be  consumed  in  preparing 
the  mouth  so  that  it  may  be  kept  in  a  hygienic  condition.  But  all  the 
necessary  cleansing  and  polishing  of  the  teeth  usually  may  be  accom- 
plished in  a  relatively  short  time  by  the  method  suggested,  not  more 
than  two  to  four  hours  all  told.  To  many,  this  may  seem  inadequate, 
but  by  actual  experience  covering  a  large  number  of  cases  the  author 
has  been  convinced  that  very  beneficial  results  may  be  obtained  by  the 
expenditure  of  time  which  is  not  beyond  the  reach  of  the  average 
practitioner.  Indeed,  for  a  given  number  of  cases  in  a  busy  practice 
the  institution  of  these  measm-es  should  result  in  an  actual  saving  of 
time  as  mouths  which  are  so  reorganized  will  have  far  less  dental  and 
peridental  disease  to  be  treated  as  time  goes  on. 

The  working  details  of  the  procedures  which  we  have  just  described 
or  the  benefits  which  are  to  be  derived  from  them  can  never  be  fully 
appreciated  by  an  operator  until  he  has  faithfully  applied  them  to  a 
variety  of  patients,  has  carefully  worked  out  his  own  method  of  obtain- 
ing the  result  and  has  watched  the  resultant  changes  which  occur  in 
the  mouths  so  treated.  Then  and  only  then  will  he  fully  understand 
the  principles  of  preventive  dentistry  and  oral  hygiene. 


CHAPTER  IV. 

INSTRUMENTATION,  CAVITY  PREPARATION  AND  THE 

FILLING  OF  TEETH  WITH  GOLD  FOIL,  GOLD 

INLAYS,  AMALGAM,  CEMENTS  AND 

GUTTA-PERCHA. 

By  JOHN  V.  CONZETT,  D.D.Sc, 

AND 

ROSCOE  H.  VOLLAND,  M.D.,  D.D.S. 

Operative  dentistry  consists  of  all  operations  that  are  performed 
upon  the  natural  teeth  and  the  tissues  directly  connected  with  them,  but 
the  modern  use  of  the  term  confines  it  to  the  operations  that  are  per- 
formed upon  the  teeth  themselves,  to  correct  the  damage  done  by  caries, 
accident,  and  unusual  wear  of  the  surfaces  of  the  teeth  in  mastication. 
Crowns,  regulations,  and  all  restorations  of  teeth  that  have  been  lost, 
are  allotted  to  other  departments  of  the  profession.  In  this  paper 
operative  dentistry  will  mean  all  operations  that  are  made  upon  the 
natural  teeth  that  have  for  their  purpose  the  restoration  of  lost  tooth 
tissue  by  means  of  fillings  or  inlays.  The  terminology  and  presentation 
of  the  subject  given  to  the  profession  by  Dr.  Black  will  be  very  largely 
followed. 

Cavity  preparation  is  fundamental  to  all  operations  on  the  teeth, 
and  as  the  basic  principles  are  the  same  for  all  materials  and  methods, 
first  the  science  of  cavity  preparation  and  the  principles  governing  the 
same  will  be  taken  up;  then,  the  various  materials  with  which  to  fill 
the  cavity  will  be  considered  with  such  exceptions  in  the  preparation  as 
the  physical  characteristics  of  the  material  may  demand. 

Fundamentally,  all  cavities  are  the  same  no  matter  what  may  be  the 
material  with  which  they  are  to  be  filled  or  what  method  may  be  used 
to  make  the  filling  whether  it  be  a  filling  of  gold  or  one  of  the  plastics 
or  whether  it  be  an  inlay  of  metal  or  porcelain.  The  only  devia- 
tion from  the  principles  that  will  be  laid  down  is  that  which  may  be 
made  imperative  by  the  method  used  in  the  filling.  For  instance,  in 
the  inlay,  it  will  be  impossible  to  use  any  retention  that  would  make  an 
undercut  of  any  description,  for  to  do  so  would  prevent  the  making  of 
a  model  or  pattern  that  would  fit  the  cavity;  in  the  making  of  a  porce- 
lain inlay  or  a  silicate  filling,  it  will  not  be  advisable  to  bevel  the  cavo- 
surface  angle,  for  the  lack  of  edge  strength  of  those  materials  would 

(179) 


180     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

militate  against  the  use  of  the  bevel,  as  that  would  leave  a  thin  edge  of 
the  filling  material  at  the  margin  of  the  cavity  that  would  soon  break 
away  and  leave  a  vulnerable  spot  for  the  beginning  of  a  recurrence  of 
decay.  In  nearly  every  respect,  the  principles  may  be  applied  to  all 
materials  and  methods,  and  in  whatever  case  it  is  thought  advisable 
to  depart  from  the  principles  here  laid  down,  it  will  be  emphasized  in 
the  consideration  of  that  particular  method  or  material. 

The  first  thing  that  the  student  should  do  in  attempting  to  fill  a 
cavity  is  to  study  the  conditions  that  surround  the  making  of  such  an 
operation.  He  should  have  a  clear  idea  of  the  cause  of  the  decay, 
whether  it  was  due  to  a  defect  in  the  tooth,  as  in  a  pit  or  fissure  cavity, 
whether  it  was  a  lack  of  cleanliness  on  the  part  of  the  patient,  as  in  all 
smooth  surface  cavities,  and  particularly  cavities  occurring  in  the  gingi- 
val surface  of  the  teeth,  or  whether  it  was  due  to  some  mal-occlusion 
that  prevented  the  proper  cleansing  of  the  portion  of  the  tooth  in  which 
the  initial  penetration  occurred.  It  is  known  that  if  it  were  possible 
to  keep  the  teeth  surgically  clean  they  would  not  decay,  and  it  is  knowu 
that  there  are  areas  of  susceptibility  and  areas  of  comparative  immunity 
upon  the  surfaces  of  the  teeth.  It  is  also  recognized  that  the  areas  that 
are  most  susceptible  are  those  that  are  the  hardest  to  keep  clean  by  the 
natural  use  of  the  teeth  in  eating.  Therefore,  if  it  were  possible  to  keep 
all  of  the  surfaces  of  the  teeth  in  the  condition  of  the  immune  areas 
there  would  be  no  decay.  In  our  study  of  the  conditions  surrounding 
the  cavity  in  a  tooth  we  should  consider  its  position  in  relation  to  the 
area  of  susceptibility  or  of  immunity;  whether  the  patient  is  negligent 
in  the  care  of  his  teeth  or  whether  the  cavity  occurred,  notwithstanding 
that  the  most  careful  attention  had  been  given  to  them.  The  operator 
should  carefully  study  the  occlusion  of  the  teeth,  for  he  will  not  be  able 
to  lay  out  intelligently  his  retentive  and  resistance  cavity  forms  unless 
he  is  familiar  with  the  stress  that  will  fall  upon  the  filling  that  he  is 
going  to  place  in  that  particular  cavity.  All  men  do  not  exert  the 
same  degree  of  stress  in  mastication.  One  patient  will  bite  with  a 
force  of  from  250  to  300  pounds  as  measured  by  the  gnathodynamom- 
eter,  while  another  one  will  only  exert  a  pressure  of  from  75  to  100 
pounds.  It  would  be  inadvisable  to  cut  as  deeply  for  retention  in 
the  case  of  the  man  with  the  weak  bite  as  in  the  case  of  the  man 
with  the  strong  one,  and  if,  on  the  contrary,  the  same  retention  were 
made  for  the  man  with  the  strong  bite  that  you  would  think  sufficient 
for  the  weak  one,  you  would  invite  failure  by  reason  of  a  lack  of  enough 
resistance  on  the  part  of  the  filling.  It  will  be  seen,  then,  how  necessary 
it  is  to  study  the  conditions  that  caused  the  initial  decay  that  we  may 
try  to  so  make  the  filling  that  there  will  be  no  recurrence  of  decay,  and 
that  the  strength  of  mastication  will  not  destroy  the  filling.     If  the 


CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH     181 

student  will  make  it  a  habit  to  study  carefully  the  conditions  surround- 
ing the  teeth  upon  which  he  is  to  operate,  and  will  then  apply  the 
principles  of  scientific  cavity  preparation  to  those  conditions,  he  w^ill 
have  the  pleasure  of  seeing  his  operations  maintain  themselves  against 
all  of  the  natural  usages  of  the  teeth  for  long  years  to  come,  but  neglect- 
ing to  do  so  will  be  disastrous  and  in  the  end  will  make  him  a  failure  in 
his  chosen  profession. 

After  a  thorough  examination  of  the  teeth  they  should  be  well  cleaned. 
If  possible  a  thorough  prophylactic  treatment  should  be  instituted 
before  any  operations  are  attempted,  for  the  reason  that  most  patients 
who  present  for  the  treatment  of  carious  teeth  have  mouths  that  are 
ill  cared  for,  and  the  attempt  to  place  the  rubber  dam  upon  such  teeth 
will  drive  many  pathogenic  organisms  under  the  gingival  margin,  with 
a  very  probable  gingival  irritation,  if  not  a  serious  infection.  If  by 
reason  of  an  aching  tooth  such  procedure  is  not  possible,  and  it  is  found 
necessary  to  make  immediate  attempts  at  relief,  the  teeth  to  be  treated 
should  be  cleaned  as  well  as  possible.  The  debris  should  be  removed 
by  forcing  an  antiseptic  spray  about  the  gingival  margin,  painting  the 
gums  with  the  tincture  of  iodin  and  then  applying  the  rubber  dam. 
But  the  dam  should  never  be  forced  upon  a  tooth  that  is  unclean  for 
fear  of  infecting  the  gum  tissue.  During  the  cleansing  of  the  teeth 
an  examination  pad  should  be  at  hand  to  mark  all  of  the  defects  that 
will  reveal  themselves  during  the  cleansing  operation,  and  this  tablet 
should  then  be  filed  away  for  reference  as  the  w^ork  progresses. 

An  artist  must  have  good  instruments  to  accomplish  good  work  and 
a  dentist  is  no  exception  to  that  rule.  The  authors  are  not  of  those 
who  believe  in  multiplying  instruments;  indeed,  they  believe  that  the 
least  number  of  instruments  that  will  perfectly  accomplish  the  desired 
result  is  the  ideal.  In  the  multiplication  of  instruments  beyond  that 
necessary  for  the  accomplishment  of  the  desired  operation  is  the 
multiplication  of  confusion.  The  student  should  thoroughly  acquaint 
himself  with  every  instrument  in  his  cabinet  and  know  just  where, 
w^hen  and  how  best  to  use  that  instrument  and  make  every  instrument 
accomplish  as  much  of  the  operation  as  possible.  The  reason  that  so 
many  operators  are  slow  and  sloven  in  their  work  is  that  they  are 
slaves  to  their  instruments  and  can  only  accomplish  a  very  little  with 
any  instrument,  and  w^hen  that  little  is  done,  must,  perforce,  find 
another  slightly  different  in  design,  in  order  to  finish  the  operation. 
The  real  artist  will  accomplish  more  with  a  piece  of  chalk  and  a  shingle 
than  will  a  bungler  wdth  the  finest  outfit  possible;  therefore,  every 
student  should  be  the  master  of  a  few  instruments  and  add  to  that  list 
those  that  experience  demonstrates  are  necessary  and  then  master 
those. 


182     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 


Fig.  119. — Woodbury-Crandall  instruments  for  cavity  preparation.  Nos.  1  and  2  are 
hatchets  for  forming  angles  in  the  anterior  teeth.  Nos.  3,  4  and  5  are  obtuse  angle  hoes. 
Nos.  6  and  7,  right  angle  hoes,  instruments  of  the  widest  application  in  cavity  formation. 
Nos.  8,  9,  10  and  11,  are  right  and  left  angle  forming  instruments,  designed  especially  for 
carrying  out  the  sharp  line  angles  in  cavities,  particularly  in  the  anterior  teeth.     Nos.  12, 


CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH     183 


A  good  mirror,  several  pairs  of  pliers,  and  five  or  six  explorers  must 
be  at  hand  to  begin  any  operation. 

The  set  of  cutting  instruments  that  were  designed  and  selected  by 
Drs.  Woodbury  and  Crandall  are  admirably  adapted  to  the  use  of 
student  and  dentist  as  well.  These  cutting  instruments  have  been 
selected  with  a  view  of  obtaining  the  greatest  service  with  the  least 
number  of  instruments.  We  append  the  description  given  by  the 
makers  of  the  selection. 

The  engine  instruments  that  will  be  necessary  are  round  burs  Nos. 
2,  4  and  6,  inverted  cone  burs  Nos.  33|,  35,  37  and  39,  fissure  burs 
Nos.  57,  58  and  59,  and  cross-cut  fissure  burs  Nos.  701,  704  and 
705.  These  should  be  for  both  the  straight  and  contra-angle  hand 
pieces.  In  addition  to  the  burs,  there  should  be  a  sandpaper  disk 
mandrel  for  straight  and  right  angle  and  a  good  assortment  of 
carborundum  and  gem  stones. 


Round. 


Inverted  cone. 


Taper, 
square  end. 


Fissure, 
square  end. 


35 


37  39 

Fig.   120 


57     58     59 


Every  student  should  know  how  to  care  for  his  instruments,  for  a  good 
workman  is  known  by  the  condition  of  his  tools.  Duplicate  sets  should 
be  in  the  case  of  every  operator  as  soon  as  he  begins  active  practice,  so 
that  an  instrument  once  used  may  be  discarded  and  not  placed  in  the 
operating  case  again  until  it  has  been  sharpened  and  sterilized. 


13,  14  and  15  are  right  and  left,  mesial  and  distal,  gingival  margin  trimmers.  Nos.  16,  17, 
18,  19,  20,  21,  26  and  27  are  right  and  left  spoon  excavators.  Nos.  22  and  23,  24  and  25 
are  right  and  left  enamel  hatchets  for  breaking  down  enamel  and  shaping  cavity  walls  in 
bicuspids  and  molars;  one  of  each  pair  is  marked  with  a  ring  to  distinguish  the  direction 
of  cut  without  examination  of  the  cutting  edge.  Nos.  28  and  29,  30  and  31  are  front  and 
back  cutting  enamel  chisels;  one  of  each  pair  is  marked  with  a  ring  so  that  those  which 
cut  on  the  back  may  be  distinguished  from  those  which  cut  on  the  face  without  examina- 
tion of  the  cutting  edge.  Nos.  32  and  33  are  special  instruments  for  cutting  mesially  and 
distally  in  molar  cavities  that  are  difficult  of  access.  Nos.  34  and  35  are  finishing  knives, 
designed  for  finding  and  removing  overlaps  along  the  gingival  margin  of  fillings  on  the 
proximate  surfaces.  Nos.  1  to  11,  22  to  25,  and  32  and  33  have  five  cutting  edges.  The 
sides  of  the  blade,  as  well  as  the  end,  are  sharpened.  These  additional  surfaces  are  used 
for  push  and  pull  cutting  in  the  final  smoothing  of  axial  walls.  After  the  end  of  the  instru- 
ment has  been  used  in  the  preparation  of  the  wall,  the  same  instrument,  with  only  a 
slight  change  of  the  hand  to  bring  the  side  of  the  blade  into  position,  is  used  to  remove  the 
slight  irregularities  left  by  the  overlapping  cuts  of  the  end  of  the  instrument.  The  enamel 
instruments,  Nos.  22  to  25,  and  28  to  31,  have  a  special  temper  differing  from  that  of  the 
other  instruments  of  the  set.  On  account  of  their  special  hardness,  they  are  not  only 
better  suited  for  removing  enamel,  but  will  hold  their  edge  longer. 


184     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

All  burs  should  be  thrown  away  as  soon  as  they  begin  to  lose  their 
edge.  Nothing  is  more  discouraging  to  an  operator  or  more  painful 
to  the  patient  than  an  attempt  to  operate  with  a  dull  bur.  The  best 
possible  obtundent  to  sensitive  dentin  is  sharp  instruments  and  their 
proper  use. 

In  sharpening  the  hand  instruments,  a  large  flat  carborundum  stone 
of  the  finest  texture  is  the  best  that  the  authors  have  found.  The 
stone  should  be  five  or  six  inches  long  and  two  or  three  inches  in  width. 

The  instrument  to  be  sharpened  should  be  held  in  the  hand  at  the 
proper  angle,  with  a  pen  grasp;  guiding  the  hand  with  the  last  knuckle 
of  the  little  finger,  the  instrument  should  be  drawn  the  whole  length  of 


Fig.  121. — Showing  proper  method  of  sharpening  instruments,  using  a  large  stone, 
the  right  method  of  holding  the  instrument,  and  the  finger  guide  on  the  stone  as  the 
instrument  is  drawn  across  it. 

the  stone  with  a  firm  pressure.  If  the  instrmnent  is  not  too  dull,  one 
or  two  passes  over  the  stone  will  sharpen  it;  but  if  it  has  completely 
lost  its  edge,  the  drawing  over  the  stone  will  have  to  be  repeated  until 
a  perfect  plane  is  reproduced.  Care  should  be  exercised  that  every 
pass  of  the  instrument  is  at  the  same  angle  or  there  will  be  a  dif- 
ferent facet  upon  the  edge  of  the  tool  for  every  passage  over  the  stone 
that  the  instrument  has  made.  The  edge  on  a  dental  instrument  should 
be  as  good  as  that  on  a  carpenter's  plane,  and  fully  as  sharp,  and 
the  student  should  never  rest  content  until  he  is  able  to  reproduce  such 
an  edge  upon  his  instruments  and  keep  it  there,  for  unless  he  does  he 
will  not  be  able  to  do  good  work. 

All  instruments  should  be  scrupulously  clean  and  should  never  be 


CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH     185 

used  upon  a  patient  until  they  have  been  carefully  sterilized  and 
sharpened. 

In  the  preparation  of  the  cavity  and  the  making  of  a  filling  of  any 
kind  it  is  best  to  apply  the  rubber  dam  for  the  following  reasons: 

(a)  It  provides  a  dry  field  of  operation. 

(6)  It  holds  lips,  cheeks  and  tongue  away  so  that  a  free  view^  of  the 
field  of  operation  may  be  secured. 

(c)  The  cuttings  and  debris  produced  in  excavating  the  cavity  are 
easily  and  quickly  removed  by  a  blast  of  warm  air. 

{cl)  The  extreme  limits  of  superficial  decay  can  be  made  out  only  on  a 
practically  dry  tooth  surface.  This  decay  will  appear  as  a  dull  white 
chalky  area  on  the  enamel  margin. 

(e)  The  partial  drying  of  the  cavity  reduces  the  sensitivity  of  the 
dentin  to  cutting  instruments. 

(/)  Since  the  cavity  is  mechanically  cleansed  and  cut  into  sound 
dentin  in  excavation  the  minimum  of  any  infective  material  is  left. 
Saliva  is  continually  charged  with  microorganisms,  and  it  is  not  desir- 
able to  permit  it  to  enter  a  cavity  after  the  excavation  is  complete. 

The  dam  should  be  medium  heavy;  a  light  dam  is  very  undesirable. 
A  dark-colored,  medium  weight  dam  is  preferred  for  the  reason  that  the 
dark-colored  one  will  better  reveal  the  holes  punched  in  it  for  the 
reception  of  the  teeth.  This  is  a  great  convenience,  for  if  a  light  dam  is 
used  the  holes  in  it  are  difficult  to  find  and  a  great  deal  of  time  is  wasted 
in  attempting  to  do  so. 

The  hole  in  the  dam  should  be  punched  in  a  manner  to  correspond 
with  the  position  of  the  necks  of  the  teeth  in  the  curve  of  the  arch,  so 
that  the  fit  of  the  dam  may  be  obtained  without  any  wrinkles  or 
stretching  of  the  rubber.  It  is  good  policy  to  start  always  at  the 
median  line  no  matter  how  far  back  in  the  mouth  the  tooth  that  is  to 
be  operated  upon  may  be,  for  the  reason  that  the  method  of  having 
many  teeth  through  the  dam  assists  in  holding  it  away  from  the 
field  of  operation,  makes  the  work  of  the  operator  easier  and  gives 
him  better  vision. 

Before  placing  the  dam,  spray  the  mouth  and  teeth  with  an  antiseptic 
solution  to  remove  any  debris  from  around  and  between  the  teeth. 
Then  go  between  all  of  the  teeth  to  be  isolated  with  a  piece  of  floss  silk, 
to  see  that  the  dam  will  be  able  to  pass  between  them.  If  an}^  obstruc- 
tion in  the  shape  of  food  debris  is  there  it  will  be  dislodged,  and  any 
sharp  cavity  margins  that  would  cut  the  dam  will  be  revealed  and  can 
then  be  removed  with  a  thin  saw  blade  or  sandpaper  strip.  If  this  is 
not  done,  difficulty  will  be  experienced  in  getting  the  dam  in  place  and 
the  possibility  of  cutting  the  rubber  is  very  great. 

With  the  teeth  prepared  for  the  reception  of  the  dam  and  the  proper 


186     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

number  and  arrangement  of  holes  punched  in  it,  it  is  ready  to  be  placed 
in  position.  In  order  to  facilitate  its  passage  between  the  teeth,  coat 
the  holes  with  soap  or  vaselin.  Some  operators  have  a  piece  of  hard 
soap  whittled  into  an  elongated  cone,  and  just  before  placing  the  dam, 
moisten  the  soap  and  insert  the  cone  into  each  hole  in  the  rubber, 
thus  coating  the  sides  of  the  hole  with  a  film  of  soap  and  lubricating 
the  rubber  so  that  it  slides  over  the  teeth  more  easily.  Perfumed 
vaselin  or  oil  may  be  used  for  the  same  purpose  and  will  be  as  effective 
and  more  pleasant  to  the  patient. 

The  dam  should  be  grasped  with  both  hands  and  the  first  hole  in  the 
rubber  placed  over  the  central  incisor.  When  that  is  perfectly  in  place, 
pass  on  to  the  lateral  and  so  on  until  all  of  the  teeth  to  be  isolated  are 
in  position;  then  place  a  properly  selected  rubber  dam  clamp  over  the 
tooth  farthest  back  and  the  fastening  of  the  rubber  dam  retainer  will 
complete  the  operation.  It  is  very  convenient  to  have  two  dam 
holders,  the  first,  the  usual  double  grasp  holder  for  use  against  the 
cheek,  and  the  second,  a  single  grasp  one  that  will  be  placed  on  the 
dam  below  the  usual  double  grasp  holder  and  passing  back  of  the 
neck  be  attached  to  the  same  position  on  the  other  side,  thus  firmly 
holding  the  dam  down  on  the  chin  and  preventing  the  lower  portion  of 
the  dam  from  coming  up,  getting  into  the  way  and  within  the  range  of 
vision  of  the  operator. 

If  the  incisors  are  the  teeth  to  be  operated  upon  it  will  be  advisable 
to  include  all  of  the  incisors  in  the  dam,  and  if  the  cavities  are  in  the 
distal  surface  of  the  central  or  in  the  laterals  or  cuspids,  it  will  be  well 
to  carry  the  dam  as  far  as  the  bicuspids,  using  a  clamp  on  the  bicuspid 
to  hold  it  in  place.  If  the  dam  has  been  properly  placed  it  will  not  be 
necessary  to  ligate  the  teeth,  but  the  edges  may  be  turned  in  under 
the  gum  by  slipping  a  piece  of  floss  silk  between  the  teeth  and  insinuat- 
ing it  under  the  dam  and  turning  the  edges  under,  which  will  help  to 
retain  the  dam  in  position.  The  teeth  and  dam  should  be  thoroughly 
washed  with  alcohol  and  dried  with  a  blast  of  warm  air.  This  will 
remove  any  oily  or  muciferous  material,  will  cause  the  dam  to  cling 
tightly  to  the  teeth  and  will  do  much  to  prevent  dislodgment.  It  may 
sometimes  be  necessary  to  ligate  the  teeth  that  are  to  be  operated  upon. 
In  doing  so  it  will  be  found  very  convenient  to  use  the  Wedelstaedt  tie. 

This  is  made  by  throwing  a  double  loop  of  silk  around  the  tooth  and 
then  uniting  the  ends  with  a  surgeon's  knot.  This  tie  has  the  advan- 
tage that  it  will  not  slip  as  you  make  the  knot,  because  the  double 
thread  will  hold  the  silk  firmly  in  place  while  the  tie  is  being  made. 
Instead  of  pushing  the  silk  under  the  gum  with  an  instrument,  it  will 
be  found  advantageous  to  place  the  ends  of  curved  pliers  between  the 
silk  loop  and  the  gum  and  then  place  the  ends  of  the  pliers  under  the 


CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH     187 

gum,  making  traction  on  the  ends  of  the  silk,  which  will  cause  the  loop 
to  follow  over  the  curved  ends  of  the  pliers  and  slide  off  them  under 
the  gum  margin,  where  it  will  be  held  in  place  while  the  silk  is  drawn 
tight  by  making  firm  traction  on  the  ends. 

A  number  of  rubber-dam  clamps  should  always  be  on  hand  and  one 
suitable  to  the  case  selected  before  attempting  to  place  the  rubber. 
If  an  assistant  is  at  hand  it  will  facilitate  the  placing  of  the  dam  to 
have  her  set  her  finger  on  the  lingual  surface  of  the  last  tooth  to  be 
included  in  the  isolated  field  and  hold  the  dam  in  place  while  you  fit 
the  clamp,  or  she  may  be  trained  to  use  the  rubber-dam  forceps  and 
place  the  clamp  on  the  tooth  after  you  have  adjusted  the  dam.  If  an 
assistant  is  not  available  the  finger  and  thumb  of  the  left  hand  may  be 
used  to  hold  the  dam  in  position  while  the  forceps  are  used  in  the  right 
hand. 


Fig.   122. — Surgeons'  knot,  also  Wedelstaedt  tie. 

Another  method  of  adjusting  the  dam  in  difficult  posterior  positions 
is  to  cut  the  holes  in  it  as  usual,  select  the  proper  clamp  and  then  insert 
it  into  the  last  hole  in  the  dam,  grasp  the  clamp  with  the  forceps  and 
place  it  over  the  tooth  indicated  in  the  isolation  scheme.  The  rubber 
will  have  to  be  somewhat  rolled  up  and  kept  in  the  hand  so  that  the 
tooth  to  be  clamped  will  not  be  obscured.  When  the  clamp  is  in  place 
draw  the  rubber  over  it  and  over  the  tooth  and  then  come  forward  and 
include  the  other  teeth  to  be  isolated  in  sequence  until  all  have  been 
included,  when  the  retainers  may  be  applied  and  the  operation  con- 
tinued. 

A  w^ell  defined  plan  should  always  precede  any  operation  and  the 
student  will  find  that  if  he  will  adopt  and  follow  a  system  that  is 
rational  he  will  make  more  progress  and  become  more  efficient  than  he 
possibly  could  by  the  hit-and-miss  fashion  of  operating.  The  system 
given  to  the  profession  by  Dr.  Black  will  be  followed  in  this  treatise: 

First,  obtain  the  required  outline  form. 

Second,  obtain  the  required  resistance  form. 


188     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

Third,  obtain  the  required  retention  form. 

Fourth,  obtain  the  required  convenience  form. 

Fifth,  remove  any  remaining  carious  dentin. 

Sixth,  finish  the  enamel  wah. 

Seventh,  make  the  toilet  of  the  cavity. 
The  outline  form  is  the  first  portion  of  the  operation  to  engage  the 
attention  of  the  student,  and  he  should  learn  to  visualize  the  finished 
filling  before  he  makes  the  first  move  in  the  preparation  of  his  cavity. 
If  he  will  learn  to  do  this  and  have  a  well-defined  plan  to  carry  out  his 
vision  he  will  soon  become  very  adept  in  his  operations;  but  if  he  has 
no  plan  in  mind  and  simply  cuts  away  until  his  cavity  bears  some 
semblance  of  a  proper  shape  he  will  waste  time  and  effort,  and  will,  in 
the  end,  obtain  a  very  inferior  result.  The  outline  form  comprehends 
the  doctrine  of  extension  for  prevention  and  the  esthetic  form. 

Extension  for  prevention  is  the  method  of  making  the  outline  of  the 
cavity  in  such  a  manner  that  all  of  the  margins  thereof  will  be  in  an 
area  that  is  relatively  immune  to  decay. 

We  stated  in  our  preliminary  remarks  that  there  were  areas  of  sus- 
ceptibility and  areas  of  relative  immunity  to  decay.  The  areas  that 
are  susceptible  are  all  of  the  defective  portions  of  the  teeth,  as  open  pits 
and  fissures,  and  those  portions  of  the  smooth  surfaces  that  are  not  kept 
clean.  Decay  begins  by  the  invasion  of  the  dental  tissues  by  micro- 
organisms attaching  themselves  to  a  surface  of  the  tooth  that  is 
not  disturbed  covering  themselves  with  a  gelatinous  membrane 
technically  called  the  bacterial  plaque.  Under  the  protection  of  this 
plaque  they  live  upon  the  carbohydrates  that  are  derived  from  the  food 
debris  left  around  the  teeth,  and  from  which  they  elaborate  lactic  acid, 
which  attacks  the  cementing  substance  of  the  enamel.  When  the 
enamel  rods  are  broken  and  fall  out  the  organisms  have  direct  access 
to  the  dentin,  the  destruction  of  the  tooth  is  then  rapid,  and,  if  not 
stopped,  complete.  The  susceptible  areas  are  those  that  are  not 
reached  by  the  food  in  its  excursions  over  the  teeth  in  mastication  or  by 
the  movement  of  the  tongue  and  lips,  or  not  kept  clean  by  the  patient 
in  his  toilet  of  the  mouth.  The  proximate  surface  of  a  tooth, 
especially  that  portion  lying  immediately  gingivally  to  the  contact 
point,  is  the  area  of  greatest  susceptibility,  and  there  will  be  found  the 
large  majority  of  the  cavities  occurring  in  the  smooth  surfaces  of  the 
teeth.  As  the  point  of  greatest  susceptibility  is  left  and  progress 
toward  the  buccal  and  lingual  angles  is  made,  a  lessening  degree  of 
susceptibility  is  found  until,  when  the  angles  are  approached,  we  will 
find  a  territory  that  is  practically  immune.  The  same  may  be  said  of 
the  march  toward  the  occlusal  and  gingival  margins  until  upon  the 
occlusal  surface  there  is  immune  territory.     Decay  is  never  found  upon 


CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH     189 

the  occlusal  or  incisal  surfaces  unless  there  is  a  defect  in  the  enamel. 
Also,  toward  the  gingival  margin  susceptible  territory  is  in  evidence 
until  the  cavity  is  carried  under  the  free  margin  of  the  gum.  On  the 
buccal  and  labial  surfaces  we  will  find  an  area  of  susceptibility  at  the 
gingival  margin  and  as  far  toward  the  occlusal  surface  as  the  curve  of 
the  tooth  will  make  difficult  the  scouring  action  of  the  bolus  as  it  passes 
over  the  tooth  in  chewing.  The  tooth  with  a  large  bell-shaped  crown 
will  have  a  larger  area  of  susceptibility  at  the  gingival  margin  than  a 
tooth  of  more  flat  outline,  occluso-gingivally,  for  in  the  case  of  the  tooth 
with  a  bell-shaped  outline  the  belling  of  the  tooth  will  cause  the  bolus 
to  miss  the  gingival  portion,  while  if  this  surface  were  more  flat  the 
food  would  have  a  scouring  action  over  the  entire  buccal  surface. 
Also,  in  the  bell-shaped  tooth  the  curve  of  the  bell  will  have  a  tendency 
to  prevent  the  frictional  action  of  the  muscles  of  the  cheek  upon  the 
gingival  portion  of  the  tooth,  while  in  a  tooth  with  a  more  nearly  flat 
surface  the  cheeks  would  move  upon  the  entire  buccal  surface,  with  a 
tendency  to  keep  bacteria  from  making  a  lodgment  upon  them.  As  we 
have  said,  the  occlusal  surfaces  of  the  teeth  are  naturally  in  immune 
territory,  for  the  mastication  of  food  would  eft'ectually  prevent  any 
organism  from  attaching  itself  to  this  surface;  but,  unfortunately,  we 
will  frequently  find  here  defects  in  the  closure  of  the  enamel  plates 
making  pits  and  fissures  into  which  the  organisms  of  decay  may 
penetrate  and  find  themselves  immune  from  the  frictional  action  of 
mastication. 

Finding  that  decay  begins  in  certain  territory  and  that  it  is  rarely 
if  ever  found  in  other  areas,  it  is  evident  that  if  a  recurrence  of  decay 
is  to  be  prevented  around  a  filling  that  is  made  to  correct  the  ravages  of 
decay  the  conditions  that  were  responsible  for  the  initial  penetration 
must  be  corrected.  In  order  to  do  that  the  susceptible  area  will  have 
to  be  restored  with  a  material  that  will  be  immune  to  the  action  of  the 
organism  that  caused  decay  and  that  material  will  have  to  be  carried 
far  enough  out  of  the  susceptible  area  to  prevent  a  recurrence  of  decay. 
If  this  is  not  done  it  will  make  no  difference  how  well  the  filling  is  made 
nor  how  perfectly  it  may  be  adapted  to  the  walls  of  the  cavity.  There 
will  be  a  recurrence  of  decay  around  it,  not  because  the  organism  can 
penetrate  between  filling  and  tooth,  but  because  the  original  fault  was 
not  wholly  corrected.  The  organisms  may  find  a  hospitable  territory 
immediately  next  to  the  filling  upon  the  surface  of  the  tooth,  and  a 
bacterial  plaque  being  established  in  that  position  there  will  be  a  new 
decay  started,  which  will  in  time  undermine  the  filling,  and  the  whole 
work  will  be  destroyed. 

In  obtaining  the  outline  form  it  will  be  seen  then  that  it  is  necessary 
to  carry  all  of  the  margins  of  the  cavity  into  areas  of  relative  immunity 


190     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

to  decay.  The  fact  is  that  in  large  cavities  the  decay  has  practically 
solved  the  outline  form  for  the  operator,  for  the  penetration  of  the 
carious  process  has  been  so  great  that  the  cutting  necessary  to  lay  the 
cavity  in  sound  tissue  will  usually  find  the  margins  in  the  area  of 
immunity.  It  means  that  the  margins  must  be  carried  buccally  and 
lingually  far  enough  out  of  the  embrasures  so  that  the  margins  of  the 
filling  will  not  be  in  contact  either  with  the  proximating  tooth  or  with  a 
filling  in  the  tooth,  and  will  therefore  be  kept  clean  by  the  progress  of 
the  food  over  the  tooth  in  mastication.  In  cavities  in  the  incisors  it 
will  be  necessary  to  carry  the  margin  far  enough  lingually  and  labially 
so  that  the  margins  of  the  filling  will  be  free  of  proximate  contact.  In  all 
cavities  in  the  proximate  surfaces  it  will  mean  the  carrying  of  the  lines 
of  the  cavity  margins  below  the  free  margin  of  the  gum.  In  the  case 
of  cavities  in  the  occlusal  surfaces  of  the  teeth  it  will  mean  that  all  of 
the  pits  and  fissures  will  be  cut  out  to  their  entire  extent  and  that  the 
margins  of  the  cavity  will  lie  in  smooth,  sound  territory.  In  short, 
extension  for  prevention  means  the  carrying  of  all  margins  of  the  cavity 
into  territory  that  can  be  kept  clean  by  the  natural  functions  of  the 
teeth,  tongue  and  lips  and  under  the  free  margin  of  the  gum. 

The  esthetic  form  is  that  form  which  we  give  to  the  outline  of  the 
cavity  that  will,  to  the  greatest  extent,  preserve  the  beauty  of  the  tooth. 
A  dentist  should  be  an  artist  as  well  as  an  artisan,  and  it  is  his  duty,  and 
should  be  his  pleasure,  to  make  all  of  his  operations  as  beautiful  as 
possible.  The  highest  art  is  to  hide  the  art  and  make  it  appear  natural, 
therefore  in  the  making  of  a  filling  it  is  of  the  utmost  importance  to  hide 
the  restorative  art  as  much  as  may  be  possible  without  the  sacrifice  of 
utility  or  the  ultimate  preservation  of  the  tooth.  When  utility  and 
esthetics  come  into  direct  antagonism,  as  they  frequently  do  in  the 
making  of  restorations  with  gold,  the  usefulness  of  the  masticatory 
organ  is  paramount  to  the  looks  of  the  same  and  the  tooth  must  be 
preserved  in  spite  of  the  lack  of  perfect  color  harmony.  In  short,  when 
the  health  and  strength  of  the  tooth  demand  the  showing  of  gold, 
do  not  hesitate  to  show  it.  Whenever  possible  make  all  of  the  opera- 
tions with  as  little  show  of  the  filling  material  as  practicable.  Make 
the  outline  form  in  such  a  way  that  the  greatest  mass  of  gold  will  be 
out  of  the  line  of  vision  and  preserve  all  of  the  enamel  possible,  thus 
preventing  the  disfiguring  display  of  gold.  But  lest  it  be  misunder- 
stood, let  it  be  repeated,  never  under  any  circumstances  hesitate  to 
display  the  gold  when  the  preservation  of  the  tooth  demands  it. 

All  of  the  external  lines  of  the  cavity  should  be  slightly  curved. 
Nature  abhors  an  angle,  and  a  sharp  angle  on  a  filling  is  inharmonious 
and  very  objectionable;  therefore  always  round  all  angles  that  come 
within  the  range  of  vision.     Internal  angles  should  be  sharp  in  order 


CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH     191 

to  make  for  a  greater  degree  of  retention,  but  outline  angles  should  be 
rounded. 

The  natural  outline  of  the  tooth  should  always  be  restored  to  as 
perfect  a  degree  as  the  skill  of  the  operator  will  permit.  A  tooth  may 
be  restored  with  a  filling  that  will  be  inharmonious  in  color,  as  with 
gold,  but  if  the  form  and  size  are  correctly  reproduced  it  will  be  much 
more  esthetic  than  if  the  color  were  to  be  perfectly  restored  while  the 
size  and  shape  were  to  be  distorted.  In  order  to  properly  reproduce 
the  contour  of  a  tooth  it  will  frequently  be  necessary  to  separate  the 
teeth  in  order  to  obtain  sufficient  space  to  make  a  perfect  form  restor- 
ation, for  the  reason  that  in  the  process  of  decay  the  teeth  have  fallen 
together  to  such  a  degree  that  a  large  part  of  the  mesio-distal  dia- 
meter of  the  tooth  has  been  lost.  If  the  loss  is  not  great,  sufficient 
separation  may  be  obtained  by  the  use  of  the  immediate  separator 
of  the  Perry  or  Ivory  type;  but  if  much  of  the  mesio-distal  diameter 
has  been  lost  it  will  be  necessary  to  separate  for  some  time  in  order 
to  obtain  sufficient  space.     This  may  be  accomplished  in  several  ways : 

(1)  The  operator  may  place  an  immediate  separator  upon  the  tooth, 
and  when  as  much  separation  has  been  obtained  as  is  deemed  wise, 
gutta-percha  may  be  packed  into  the  cavity  and  left  for  several  days, 
the  patient  being  instructed  to  call  again,  when  the  same  process  may 
be  repeated  until  a  sufficient  amount  of  space  has  been  obtained  to  make 
the  proper  restoration.  (2)  The  cavity  may  be  cleaned  out  and  a 
gutta-percha  filling  made,  which  will  be  a  little  more  full  than  normal, 
so  that  the  patient  will  bite  upon  the  filling.  After  wearing  this  for  a 
week  a  larger  amount  of  the  material  may  be  placed  in  the  cavity  and 
this  repeated  as  often  as  necessary  until  the  required  space  is  secured. 
This  last  method  is  the  least  painful  and  the  best. 

The  resistance  form  is  that  form  given  to  a  cavity  which  will 
enable  the  filling  placed  therein  to  withstand  the  stress  that  falls 
upon  it  in  mastication.  When  it  is  remembered  that  a  filling  will 
have  to  stand  the  masticatory  stress  of  from  100  to  300  pounds  at  each 
closure  of  the  jaw  in  the  act  of  chewing  the  food,  some  idea  is  obtamed 
of  the  necessity  of  studying  closely  the  best  form  to  give  the  cavity,  so 
that  a  filling  placed  in  it  will  be  able  to  bear  this  tremendous  strain. 
The  best  foundation  known  is  the  flat  base,  and  the  best  form  that  can 
be  given  a  cavity  is  a  flat  base  with  parallel  walls.  A  box  with  flat 
seats  and  walls  at  a  right  angle  would  be  the  ideal  cavity,  and  as  nearly 
as  possible  this  should  be  the  cavity  that  the  student  should  strive 
to  obtain.  In  cavities  occurring  in  the  proximo-occlusal  surfaces  of 
molars  and  bicuspids  the  double  step  is  used,  one  in  the  occlusal  surface, 
called  the  occlusal  step,  and  one  in  the  gingival  portion  of  the  proximate 
surface,  called  the  gingival   step.     These  fillings  have  to  bear  the 


192     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

greatest  amount  of  stress,  and  this  preparation  best  confers  the  abihty 
to  withstand  the  force  brought  to  bear  upon  them. 

The  retention  form  is  that  form  given  to  a  cavity  which  pre- 
vents the  displacement  of  the  filHng  from  any  cause  and  consists  very 
largely  of  the  same  methods  used  in  the  resistance  form,  that  is,  the 
flat  seats  and  parallel  walls.  If  the  gold  or  filling  material  is  thoroughly 
condensed  no  other  preparation  is  necessary,  for  the  force  of  condensa- 
tion will  displace  the  elastic  dentin  slightly  and  the  resultant  spring  of 
the  dentin  will  cause  it  to  so  hug  the  filling  material  that  it  will  be 
impossible  to  dislodge  it.  However,  it  is  permissible  to  shape  the 
cavity  so  that  it  will  be  self -retentive;  that  is,  the  internal  portion 
thereof  will  be  larger  than  the  orifice,  making  a  dovetail  arrangement 
of  the  whole  cavity,  which  will  prevent  the  displacement  of  the  filling 
short  of  breaking  the  tooth.  This  dovetailing  should  be  very  slight, 
for  it  is  not  necessary  to  make  much  retention,  and  more  than  is  neces- 
sary is  obtained  at  the  sacrifice  of  useful  dentin  and  the  consequent 
weakening  of  the  tooth. 

The  convenience  form  is  that  form  which  we  give  a  cavity  which  will 
enable  the  operator  to  fill  it  more  conveniently.  After  all,  the  filling 
of  the  cavity  is  of  the  greatest  importance,  for  no  matter  how  perfectly 
it  has  been  prepared,  if  the  filling  material  is  not  inserted  so  that  it 
hermetically  seals  the  cavity  the  operation  will  be  a  failure.  For  this 
reason  it  is  of  the  greatest  importance  to  make  the  cavity  of  such  shape 
that  the  operator  can  fill  it  perfectly.  It  is  not  possible  to  lay  down  any 
hard  and  fast  law  on  this  subject,  for  here  more  than  any  other  place 
the  personal  equation  of  the  operator  comes  into  play.  One  operator 
will  be  able  to  fill  perfectly  a  cavity  that  will  be  impossible  to  another; 
therefore  the  only  rule  that  can  be  made  is  that  every  cavity  should  be 
shaped  so  that  the  operator  can  fill  it  perfectly.  One  rule  that  is 
universally  true  is  that  in  the  making  of  a  gold-foil  filling  all  portions  of 
the  cavity  should  be  so  accessible  that  the  plugger  point  can  perfectly 
reach  them,  for  gold  cannot  be  condensed  around  a  corner. 

Pits  and  pothooks  are  no  longer  permissible,  for  they  are  not  only 
useless  as  a  means  of  retention  but  are  positively  harmful.  A  con- 
venience pit  may  be  used  as  a  help  in  starting  the  gold,  but  not  as  a 
means  of  retention.  This  sort  of  a  pit  should  not  be  deep,  only  deep 
enough  to  enable  the  operator  to  start  his  pellet  of  gold  and  have  it 
retained  until  he  is  able  to  fill  that  portion  of  the  cavity  and  have  the 
general  retentive  form  hold  the  gold  firmly  from  that  on.  Many 
operators  do  not  use  a  convenience  pit  at  all,  simply  depending  upon  the 
point  in  one  of  the  gingival  angles  for  a  starting  place. 

The  removal  of  any  remaining  carious  dentin  should  always  be  in- 
sisted upon.     Usually  when  the  preparation  of  the  cavity  has  pro- 


CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH     193 

gressed  thus  far  all  of  the  infected  dentin  has  been  cut  out,  but  in  deep- 
seated  cavities  there  may  be  some  decayed  dentin  left,  and  this  should 
be  carefully  sought  out  and  removed,  for  any  carious  dentin  is  a  menace 
to  the  filling  and  a  greater  one  to  the  life  of  the  pulp.  This  should  be 
removed  with  a  spoon  excavator  of  as  large  a  dimension  as  the  size  of 
the  cavity  will  permit. 

The  preparation  of  the  enamel  walls  contemplates  the  beveling  and 
smoothing  of  the  enamel  margins.  It  may  be  remembered  that  the 
outline  form  was  obtained  as  the  first  part  of  the  cavity  preparation, 
but  the  beveling  and  smoothing  of  the  enamel  margins  was  left  as  the 
last  part  of  the  operation,  for  in  the  progress  of  the  work  the  enamel 
margins  might  be  injured  and  roughened;  therefore,  the  final  finishing 
of  this  important  portion  of  the  cavity  is  left  until  the  last.  The  enamel 
margins  should  be  beveled  all  around  the  cavity  for  the  protection  of 
the  enamel  margins  themselves.  In  the  study  of  the  structure  of  the 
enamel  it  will  be  remembered  that  it  is  composed  of  rods  standing  upon 
end,  resting  upon  the  dentin,  and  in  their  general  arrangement  agreeing 
to  the  form  of  the  dentin.  In  studying  the  splendid  reproduction  of 
Dr.  Frederick  B.  Noyes'  diagram  upon  the  subject  it  will  be  noticed 
that  while  there  is  a  general  agreement  of  the  enamel  rods  in  their 
direction  to  that  of  the  dentin,  in  some  very  important  places  there  is  a 
discrepancy  in  their  following  the  form  of  the  dentin. 

At  the  extreme  gingival  portion  the  enamel  rods  have  a  root-wise 
inclination,  and  as  they  approach  the  middle  third  of  the  tooth  they 
straighten  up,  so  that  at  that  portion  of  the  tooth  they  are  practically 
perpendicular  to  the  dentin.  As  they  approach  the  cusp  of  the  tooth 
the  rods  incline  in  the  opposite  direction,  until  at  the  apex  of  the 
dentin  cusp  they  are  again  perpendicular  to  the  dentin.  Passing 
over  the  cusps  they  are  found  inclining  toward  the  sulcus  or  fissure,  if 
there  is  one,  and  in  the  immediate  vicinity  of  the  fissure  they  join  their 
fellows  on  the  opposite  side  in  falling  together  to  such  an  extent  that 
a  cut  through  this  territory  will  find  no  short  rods  upon  the  surface. 
A  study  of  this  diagram  will  do  more  to  teach  the  student  the  wisdom 
and  necessity  of  beveling  the  enamel  walls  than  anything  known.  By 
studying  this  it  will  be  seen  that  a  margin  made  in  the  gingival  region, 
if  cut  straight  across  the  horizontal  axis  of  the  tooth,  would  leave  a 
large  number  of  short  enamel  rods;  that  is,  rods  that  were  so  cut  that 
the  dentin  portion  did  not  rest  upon  the  dentin.  They  were  cut  off 
from  their  dentin  base,  and,  as  a  consequence,  are  in  a  very  weak  con- 
dition, so  that  the  slightest  stress  will  cause  them  to  fall  out  and  leave 
a  vulnerable  spot  in  the  filling.  All  modern  operators  are  convinced 
that  more  failures  are  due  to  this  fault  in  cavity  preparations  than  any 
other,  with  the  exception  of  a  failure  to  carry  out  the  lines  of  extension. 
13 


194     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 


Fig.   123. — Diagram  of  enamel  rod  directions,  from  a  photograph'of  a  bucco-lingual 
section  of  an  upper  bicuspid.     (Noyes.) 


Fig.    124. — -Diagram  of  enamel  rod  directions,  drawn  from  a  mesio-distal  section  of  a 

bicuspud.     (Noyes.) 


CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH     195 

On  the  contrary,  when  a  pit  or  fissure  is  approached  it  will  be  found 
that  their  arrangement  is  of  such  a  nature  that,  as  they  are  inclined 
toward  each  other  and  into  the  cavity,  a  straight  cut  through  them  will 
leave  no  short  rods  upon  the  surface.  In  the  immediate  vicinity  of  a 
pit  or  fissure,  therefore,  it  is  not  absolutely  necessary  to  bevel  the  mar- 
gin, and  we  do  so  only  to  be  sure  that  we  have  removed  any  rods  that 
have  been  injured  in  the  operative  procedures.  At  all  developmental 
lines  the  rods  are  weak,  and  it  is  always  a  rule  in  the  management  of 
the  enamel  margin,  when  a  developmental  line  is  approached,  to  go 
beyond  it  and  lay  the  margin  in  the  strong  enamel  beyond  the  line  of 
fusion. 

It  will  be  noticed  that  as  the  enamel  rods  approach  the  cusps  of  any 
of  the  teeth  they  incline  toward  the  cusp.  This  will  necessitate 
making  a  very  decided  bevel  as  the  cusp  is  approached,  until  arriving  at 
the  crest  of  the  cusps  it  is  the  part  of  wisdom  to  go  beyond  and  cut  off 
the  enamel  and  reproduce  it  in  gold.  A  failure  to  do  so  will  endanger 
the  filling  by  causing  a  breaking  down  of  the  enamel  rods  with  an  ulti- 
mate destruction  of  the  entire  filling. 

The  beveling  of  the  enamel  margins,  or  the  making  of  the  cavo-sur- 
face  angle,  as  it  is  technically  called,  should  be  done  with  sharp  chisels 
and  marginal  trimmers.  The  occlusal  and  proximate  portions  may 
be  made  with  a  chisel,  but  the  gingival  margins  will  be  best  obtained 
with  the  marginal  trimmers.  Some  operators  prefer  to  make  the  re- 
quired enamel  bevel  with  sand-paper  disks  and  strips,  but  this  is  an 
error  in  technic,  for  the  reason  that  a  definite  bevel  cannot  be  as  readily 
obtained  in  this  way,  and  for  the  further  reason  that  the  gold  can- 
not be  adapted  as  easily  to  a  polished  surface  as  to  a  planed  one. 
Furthermore,  the  chisel  in  the  hands  of  an  observant  operator  is  the  best 
indicator  of  the  direction  of  the  enamel  rods.  While  in  the  main  the 
diagram  of  Dr.  Noyes  is  correct,  yet  there  are  so  many  exceptions  to 
the  rule  that  the  operator  is  never  sure  of  the  lay  of  the  rods  in  any 
position  on  the  surface  of  the  tooth,  except  as  it  has  been  tested  by  the 
cleavage  under  the  chisel.  Therefore  the  chisel  in  his  hands  becomes 
the  best  possible  guide  as  to  where  and  how  the  enamel  bevel  should  be 
made  in  any  particular  case. 

The  toilet  of  the  cavity  comprehends  the  thorough  cleansing  of  the 
cavity  of  all  chips  and  debris.  As  all  of  the  operation  has  been  con- 
ducted under  the  rubber  dam  the  tooth  is  in  the  best  possible  condition 
for  the  reception  of  the  gold,  without  any  further  treatment.  If  the 
chip  blower  does  not  remove  all  of  the  cavity  debris  a  piece  of  cotton 
or  spunk  in  the  pliers  will  be  all  that  is  necessary.  The  freshly  cut 
dentin  is  in  the  best  condition  against  which  to  pack  the  gold,  so  no 
medicament  of  any  description  should  be  placed  therein.     If  any 


196     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

moisture  has  penetrated  to  the  tooth  it  should  be  dried  thoroughly  and 
the  dentin  freshened  by  slightly  cutting  the  surface  with  a  sharp  hoe. 

There  are  five  classes  of  cavities  which  are  named  according  to  the 
tooth  and  their  position  on  the  surface  thereof: 

Class  I.  Cavities  having  their  beginning  in  the  defects  of  tooth 
structure,  as  fissure  and  pit  cavities. 


Buccal  Wall 


Distal  Wall 


Mesial  Wall 


Lingual  Wall  Pulpal  Wall 


Fig.   125. — Occlusal  cavity  in  the  lower  first  molar,  illustrating  Class  I  cavities  and 

names  of  their  walls. 


Pulpal  Wall 


Buccal  Wall 


Lingual  iVall 


Gingival  Wall  Axial  Wall 


Fig.    126. — Mesio-occlusal  cavity  in  the  upper  first  molar,  illustrating  Class  II  cavities 

and  names  of  their  walls. 


Class  II.  Cavities  having  their  beginning  in  the  proximate  surfaces 
of  bicuspids  and  molars. 

Class  III.  Cavities  having  their  beginning  in  the  proximate  surfaces 
of  incisors  and  cuspids  not  involving  the  angle. 

Class  IV.  Cavities  having  their  beginning  in  the  proximate  surfaces 
of  incisors  and  cuspids  involving  the  angle, 


CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH     197 


Class  ^^     Cavities  having  their  beginning  in  the  gingival  surfaces  of 
any  of  the  teeth. 


Labial  Wall 


Gingival  Wall 
Axial  Wall 
Lingvxil  Wall 


Fig.    127. — Mesial  cavity  in  the  upper  central  incisor,  illustrating  Class  III  cavities  and 

names  of  their  walls. 


GingivalWall 


Axial  Wall 


Labial  Wall 


Lingual  Wall 
Distal  Wall 


Pulpal  Wall 


Fig.  128. — Mesio-incisal  cavity  in  the  upper  central  incisor,  illustrating  Class  IV  cavities 

and  names  of  their  walls. 


Gingival  Wall 


Mesial  Wall 


Distal  Wall 


Axial  Wall 


Incisal  Wall 


Fig.   129. — Labial  cavity  in  the  upper  central  incisor,  illustrating  Class  V  cavities  and 

names  of  their  walls. 

In  the  preliminary  considerations  we  presented  a  plan  of  operation 
that  should  be  carried  out  in  the  preparation  of  any  cavity,  and  in 


198     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

following  the  system  it  is  advisable  to  adopt  the  sequence  there  given, 
though  it  is  possible  to  combine  some  of  them  in  actual  operation;  for 
instance,  the  resistance  and  retentive  forms  are  so  nearly  alike  in  prac- 
tice that  it  is  nearly  always  possible  to  make  them  at  the  same  time. 
After  one  has  been  accustomed  to  this  system  of  operation  it  will  become 
involuntary  and  will  be  followed  without  conscious  thought  or  effort. 
'  It  is  at  this  condition  that  the  student  should  try  to  arrive,  for  the  best 
work  is  that  which  has  been  done  so  many  times  that  the  eyes  and  hands 
have  been  so  trained  that  they  coordinate  every  step  of  the  operation 
without  conscious  effort,  just  as  the  organist  plays  the  most  difficult 
compositions  without  giving  thought  to  the  technic,  but  devotes  his 
entire  attention  to  the  interpretation  of  the  composer's  thought,  the 
hands  and  feet  involuntarily  carrying  out  the  designs  of  the  composer. 
Thus  the  dental  operator,  by  repeatedly  following  the  system  here 
given,  finally  arrives  at  the  point  where  the  system  and  its  rules  and 
sequences  are  followed  involuntarily,  while  the  whole  effort  of  the 
operator  is  given  to  idealizing  his  work. 

By  reason  of  the  failure  of  nature  to  close  the  enamel  plates  by  fusion 
with  one  another  there  will  be  a  pit  or  fissure  left  at  the  point  of  failure 
which  will  make  an  ideal  place  for  the  organisms  of  decay  to  penetrate 
and  begin  the  work  of  tooth  destruction.  Such  places  are  the  fissures 
in  the  occlusal  surfaces  of  bicuspids  and  molars,  the  pits  in  the  buccal 
surfaces  of  the  lower  and  lingual  surfaces  of  upper  molars  and  in  the 
lingual  surfaces  of  the  upper  incisors,  particularly  the  laterals. 

Class  I  Cavities. — If  the  carious  process  is  just  beginning  there  will  be 
only  a  fissure  with  very  little  decay,  and  that  at  a  slight  depth.  This 
is  the  ideal  time  to  fill  the  tooth  and  prevent  further  destruction  of 
tissue,  or  any  possible  pulp  complications  by  the  incursion  of  the 
pathogenic  organisms,  thereby  causing  irritation  which  might  possibly 
lead  to  inflammation  and  death. 

Since  the  decay  is  very  slight  it  will  be  necessary  to  open  up  the  cavity 
with  an  engine  instrument.  A  cross-cut  fissure  bur  No.  702  is  the  best 
instrument  with  which  to  do  this  the  most  rapidly  and  efficaciously.  The 
bur  should  be  placed  in  the  point  of  entrance  of  the  decay,  and,  when  it 
has  penetrated  through  the  enamel,  rapidly  follow  the  fissures  to  their 
entire  extent.  With  chisel  No.  28  or  No.  29  and  mallet  the  enamel 
may  now  be  broken  down  to  some  extent,  when,  with  an  inverted  cone 
No.  37  or  No.  39  the  enamel  may  be  undermined  by  cutting  the  dentin 
from  underneath  the  same.  At  the  same  time  the  depth  of  the  cavity 
may  be  obtained  and  the  floor  somewhat  flattened.  In  this  way  the 
required  outline  form  is  secured  and  at  the  same  time  some  progress  is 
made  in  obtaining  the  resistance  and  retentive  forms.  When  the 
enamel  has  been  undermined  sufficiently  for  the  chisel  to  break  it  the 


CLASS  I  CAVITIES  199 

chisel  should  again  be  used  and  the  entire  outline  form  obtained.  This 
will  mean  that  all  of  the  fissures  are  eliminated  and  the  margins  of  the 
cavity  are  laid  in  smooth  sound  tissue. 

In  a  cavity  of  this  class  there  will  be  very  little  need  of  a  resistance 
form,  for  the  force  of  masticatory  stress  will  have  a  tendency  to  pound 
the  filling  into  the  cavity,  so  the  resistance  and  the  retentive  forms  will 
be  identical.  This  form  will  consist  of  a  flat  pulpal  wall,  with  the 
lateral  walls  perpendicular  to  it,  making  the  whole  cavity  as  nearly 
like  a  box  as  possible.  The  depth  of  the  cavity  will  depend  upon  the 
force  of  mastication,  for  a  heavy  masticatory  stress  would  cause  the 
gold  in  a  shallow  cavity  to  flow  and  the  filling  would  fail  as  a  result. 
The  cavity  should  always  penetrate  the  enamel  and  have  the  seat  made 
in  dentin.  It  is  rarely  possible  to  make  a  filling  that  will  stand  the 
stress  of  years  of  mastication  with  a  depth  of  less  than  1|  mm.,  and  it 
would  be  as  rare  to  have  one  deeper  than  2|  mm.  If  the  penetration 
of  decay  calls  for  a  greater  depth  than  that,  it  will  be  wise  to  fill  the 
cavity  with  a  cement  first,  allowing  the  patient  to  wear  this  filling  for  a 
week  or  more,  and  then,  if  all  is  well,  make  the  cavity  of  the  proper 
depth,  with  the  cement  as  a  base.  If  there  is  only  one  point  of  deep 
penetration,  which  is  often  the  case,  make  the  depth  of  the  cavity 
without  considering  the  depth  of  penetration  of  this  one  point :  do  not 
attempt  to  cut  the  floor  of  the  cavity  to  the  depth  of  the  deepest  part. 
Make  the  rest  of  the  floor  flat  at  the  required  depth  and  then,  when 
finished,  remove  the  decay  from  the  part  of  deepest  penetration  and 
proceed  to  fill  in  this  way. 


Fig.   130. — Occlusal  cavity  in  the  lower  first  molar. 

In  a  cavity  in  this  situation  the  convenience  form  is  negligible,  for 
all  parts  of  the  cavity  are  accessible.  However,  if  the  filling  is  to  be  of 
cohesive  gold,  do  not  make  an  undercut  or  even  a  perfectly  perpendicu- 
lar wall  on  the  mesial,  for  to  do  so  would  make  the  adaptation  of  gold 
at  this  point  rather  difficult  (Fig.  130). 

Slightly  incline  this  wall  mesially  so  that  the  plugger  may  reach  the 


200     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

bottom  of  the  cavity  and  perfectly  adapt  the  gold  to  the  walls.  The 
slight  loss  of  retention,  because  of  this  preparation,  will  be  more  than 
compensated  by  the  ease  of  access  and  perfection  of  condensation  of  the 
gold.  If  the  filling  is  to  be  one  of  non-cohesive  gold  this  convenience 
form  should  be  discarded  and  a  sharp,  square  angle  made  at  the  mesial 
portion  of  the  cavity,  for  it  will  not  be  hard  to  adapt  the  non-cohesive 
gold  to  an  angle  even  though  the  line  of  force  is  not  perfectly  obtain- 
able. The  paralleling  of  the  walls  of  the  cavity  can  best  be  made  by 
the  use  of  a  fissure  bur  in  the  contra-angle  hand-piece  and  the  angles 
made  sharp  with  a  hatchet. 

All  of  the  remaining  carious  dentin  should  now  be  removed.  There 
will  usually  be  none  left  except  in  those  cases  in  which  there  is  a  deeper 
penetration  of  decay  than  it  is  thought  advisable  to  make  the  cavity, 
in  which  case,  remove  the  remaining  carious  dentin  until  sound  tissue 
is  found.  The  decay  can  best  be  removed  with  a  spoon  excavator  of  as 
large  size  as  the  cavity  will  permit.  The  instrument  should  be  placed 
under  the  decay  and  the  whole  mass  lifted  out  of  the  cavity.  When  all 
of  the  decay  has  been  removed  it  is  well  to  thoroughly  plane  the  under- 
lying dentin  to  remove  any  infection  and  provide  good,  healthy  tissue 
against  which  to  condense  the  gold. 

The  finishing  of  the  enamel  margins  is  the  last  act  in  the  preparation 
of  the  cavity  and  consists  of  smoothing  all  the  lines  of  the  cavity  margin 
and  obtaining  the  cavo-surface  angle.  This  should  be  made  with  a  very 
sharp  chisel,  carefully  ascertaining  the  direction  of  the  enamel  rods  and 
then  making  a  bevel  about  one-quarter  of  the  thickness  of  the  enamel 
all  around  the  cavity.  It  is  best  to  make  the  cavo-surface  angle  with  a 
planing  instrument  rather  than  a  stone  or  disk,  because  it  has  been 
demonstrated  that  gold  can  be  more  easily  adapted  to  a  planed  surface 
than  to  a  polished  one. 

The  toilet  of  the  cavity  is  made  by  the  removal  of  any  chips  or  debris 
of  any  kind  that  may  be  left  as  a  result  of  the  preparation  of  the  cavity. 
The  debris  may  usually  be  removed  with  a  blast  of  warm  air,  but  if  not 
the  cavity  should  be  wiped  out  with  a  piece  of  cotton  or  spunk.  No 
liquid  of  any  sort  should  be  used  in  the  cavity,  and  if  it  becomes  moist 
through  the  leaking  of  the  saliva  through  the  rubber  dam,  or  from  any 
other  cause  the  cavity  should  be  thoroughly  dried  and  the  dentin 
freshened  by  going  over  it  with  a  chisel  or  hoe.  In  case  of  close  proxim- 
ity to  the  pulp  and  the  danger  of  thermal  shock  some  non-conducting 
substance  may  be  placed  between  the  gold  and  dentin.  Dr.  Black 
advises  a  piece  of  quill,  and  this  is  very  good.  A  good  substitute  may 
be  made  of  a  piece  of  thin  celluloid,  cut  so  that  it  accurately  fits  the 
bottom  of  the  cavity.  Or  a  little  cavitin  may  be  placed  in  the  cavity, 
care  being  used  that  none  of  it  comes  in  contact  with  the  walls  or 


CLASS  I   CAVITIES 


201 


margins  thereof.  On  the  evaporation  of  the  menstruum  a  thin  layer  of 
celluloid  will  be  adherent  to  the  dentin  and  will  make  a  very  good 
non-conductor  of  thermal  changes. 

Cavities  occurring  in  the  pits  of  upper  molars  are  also  Class  I  cavities 
and  are  treated  in  the  same  manner  as  those  in  the  occlusal  surfaces  of 
the  lower  molars.  The  floors  of  the  cavity  are  made  flat,  the  walls 
perpendicular  to  the  floors  and  parallel  to  each  other  as  much  as  the 
nature  of  the  case  will  admit  and  the  enamel  margins  beveled  all  around 


Fig.  131 


Fig.  132  Fig.  133 

Figs.  131,  132  and  133. — -Occlusal  cavities  in  the  upper  first  molar.  Fig.  131  show- 
ing cavities  in  central  pit  and  distal  fissure  filled  separately.  Fig.  132  showing  trans- 
verse ridge  cut  across  and  pit  and  fissure  cavities  made  as  one.  Fig.  133,  same  as  Fig. 
132,  but  disto- lingual  fissure  involved. 


the  cavity.  If  the  oblique  ridge  has  not  been  undermined  and  the 
cavities  are  confined  to  the  pits  in  the  occlusal  surface  of  the  upper 
molar  it  will  not  be  wise  to  cut  across  the  ridge  and  make  the  cavity  as 
one,  but  allow  the  ridge  to  remain  intact,  prepare  a  cavity  in  each 
pit  and  treat  them  separately.  In  case  the  decay  has  progressed  to 
such  an  extent  that  the  oblique  ridge  has  been  appreciably  undermined, 
it  will  be  well  to  cut  through  the  ridge,  unite  the  cavities  having  their 
beginnings  in  the  central  and  distal  pits  and  make  them  as  one.  In 
this  case  the  treatment  will  be  practically  identical  with  that  of  a  cavity 


202     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

in  the  occlusal  surface  of  the  lower  molar,  except  for  such  slight  changes 
as  the  anatomic  form  of  the  tooth  will  demand.  If  the  lingual 
marginal  ridge  remains  intact  the  lingual  margin  of  the  cavity  may  be 
established  just  before  reaching  the  crest  of  the  marginal  ridge.  But 
if,  as  frequently  happens  the  disto-lingual  fissure  is  defective  through- 
out its  length  it  is  necessary  to  carry  the  cavity  over  the  marginal 
ridge  onto  the  lingual  surface  of  the  tooth.  Then  the  fissure  should  be 
cut  out  the  entire  length  until  the  margin  will  be  laid  in  the  smooth 
territory  to  the  gingival  of  the  fissure.  The  fissure  should  be  followed 
with  a  No.  702  cross-cut  fissure  bur  and  the  enamel  broken  down  to  the 
outline  form  with  a  chisel.  The  gingival  wall  should  be  made  flat  with 
a  No.  35  or  No.  37  inverted  cone  bur  followed  by  the  use  of  an  obtuse 
angle  hoe  of  proper  size  to  fit  the  situation.  The  mesial  and  distal 
walls  may  be  paralleled  by  the  use  of  the  inverted  cone  or  the  fissure 
bur.  A  fissure  bur  is  preferable  in  this  situation.  The  making  of  the 
cavo-surface  angle  offers  but  one  point  of  emphasis,  and  that  is  the 
lingual  marginal  ridge.  The  cavity  as  it  p&,sses  over  this  marginal  ridge 
finds  the  enamel  rods  bent  toward  the  fissure  and  consequently  in  a 
favorable  condition  to  withstand  the  force  of  masticatory  stress,  for  no 
short  rods  are  likely  to  be  left  upon  the  surface  as  a  result  of  the  prepara- 
tion of  the  cavo-surface  angle  even  though  a  straight  cut  were  made 
through  the  fissure.  Owing  to  the  unusual  stress  that  will  inevitably 
come  upon  this  portion  of  the  filling  it  will  be  well  to  make  a  rather  long 
bevel  so  that  the  margins  may  be  strengthened  and  at  the  same  time  the 
filling  so  made  that  it  will  be  able  to  withstand  the  stress  of  occlusal 
force  without  flowing.  Convenience  angles  may  be  made  in  the  disto- 
axial  and  mesio-axial  angles,  but  the  one  in  the  mesio-axial  angle  should 
not  be  very  pronounced,  for  if  it  were  it  would  be  difficult  to  reach  it 
with  the  point  of  the  plugger  and  an  imperfect  condensation  of  the  gold 
at  that  point  would  result.  In  preparing  a  cavity  for  the  reception  of 
a  gold  filling  it  should  be  in  the  operator's  mind  never  to  prepare  any 
angle  or  position  of  the  cavity  in  such  a  way  that  it  will  not  be  perfectly 
accessible  to  the  plugger,  for  gold  cannot  be  well  condensed  around  a 
corner.  The  attempt  to  seal  hermetically  a  place  in  a  cavity  that  is 
inaccessible  to  the  plugger  point  will  invite  infiltration  decay  by 
reason  of  a  failure  to  perfectly  adapt  the  filling  material  to  the  dentin 
at  that  point. 

Cavities  occurring  in  the  pits  and  fissures  of  the  bicuspids,  both  upper 
and  lower,  are  Class  I  cavities,  and  their  treatment  calls  for  no  further 
amplification.  The  seats  should  be  made  flat  and  only  as  deep  as  the 
carious  condition  will  demand,  for  here  there  will  be  no  unusual  stress 
and  the  carrying  of  the  depth  of  the  cavity  through  the  enamel  will  be 
sufficient  to  maintain  the  integrity  of  the  filling.     In  case  there  is  a 


CLASS  f^C  AVI  TIES  203 

deeper  penetration  of  the  decay  it  will  be  necessary  to  make  the  cavity 
deeper,  of  course,  but  the  resistance  and  retentive  forms  are  amply 
provided  for  if  the  filling  is  well  anchored  in  the  dentin. 

Cavities  in  the  buccal  surfaces  of  the  lower  molars  and  lingual  sur- 
faces of  the  upper  incisors  are  pit  cavities  and  therefore  in  Class  I. 
Their  preparation  will  be  with  the  flat  seat,  parallel  walls  and  the  bevel- 


a  h  c  d 

Fig.    134. — Occlusal  cavities  in  the  bicuspids,     a,  lower  first  bicuspid;    b,  lower  second 
bicuspid;  c,  upper  second  bicuspid;  d,  upper  first  bicuspid. 

ing  of  the  cavo-surface  angle.  No  special  mention  need  be  made  of  the 
preparation  of  these  cavities,  except  to  warn  the  student  against  the 
exposure  of  the  pulp  in  the  case  of  the  cavities  in  the  lingual  surfaces 
of  the  upper  incisors.  If  a  very  deep  preparation  should  be  attempted 
there  would  be  a  great  danger  of  pulp  complications.  These  cavities 
should  be  sought  out  at  the  very  first  opportunity  and  filled  before  there 


Fig.    135. — Buccal  cavity  in  the  lower  first  Fig.    136. — Lingual  cavity  in  the 

molar.  upper  lateral  incisor. 

is  any  great  penetration  of  decay.  The  depth  of  the  cavity  need  not 
be  great  for  there  will  be  little  stress  in  this  situation  and  a  deep  resist- 
ance form  is  not  necessary.  The  convenience  angles  should  be  made 
in  the  disto  and  mesio-gingivo-axial  angles  for  a  point  in  the  inciso- 
axial  angle  would  be  so  out  of  the  line  of  force  that  it  would  be  difficult 
to  fill  perfectly.     Therefore,  the  retention  should  be  made  by  the  box- 


204    CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

like  form  of  the  cavity  assisted  by  the  angles  in  the  gingival  portions 
of  the  cavity,  making  the  angle  in  the  incisal  portion  as  acute  as  possible 
to  reach  with  the  plugger  point,  but  no  more.  Fortunately,  no  great 
degree  of  stress  falls  upon  a  filling  made  in  this  situation  so  that  a  great 
deal  of  retention  is  not  necessary,  and  a  perfect  adaptation  of  the  gold 
to  the  cavity  is  of  more  importance  than  the  resistance  or  retentive 
forms. 

There  are  a  number  of  weak  spots  in  the  enamel  in  this  surface, 
being  at  the  developmental  lines,  and  care  should  be  taken  to  seek  them 
out,  remove  any  frail  portions,  and  so  bevel  the  margins  that  the 
enamel  will  be  perfectly  protected. 


Fig.   137. — Mesio-occlusal  cavity  in 
lower  first  mola,r. 


Fig.   138. 


-Mesio-occlusal  cavity  in  lower 
second  molar. 


Class  II  Cavities. — Class  II  cavities  are  those  having  their  beginnings 
in  the  proximate  surfaces  of  bicuspids  and  molars.  The  decay  has  its 
inception  on  the  proximate  surface  of  the  tooth  just  gingivally  to  the 
contact  point,  and  is  not  apparent  to  the  patient  until  it  has  made  con- 
siderable progress;  perhaps  not  until  the  carious  process  has  gone  so 
far  that  a  sudden  force  upon  the  occlusal  portion  of  the  tooth  in  mastica- 
tion breaks  the  marginal  ridge  and  the  cavity  is  opened  up,  when  the 
patient  presents  with  the  statement  that  the  cavity  came  all  at  once. 
It  is  sometimes  difficult  for  the  dentist  to  find  these  cavities  in  their 
inception,  and  yet  that  is  the  time  they  should  be  located  and  filled; 
therefore,  it  is  the  duty  of  the  dentist  to  make  a  careful  search  for  this 
class  of,  cavities,  using  small  curved  explorers  for  the  purpose,  being 
assisted  by  the  use  of  the  electric  mouth  lamp  and  compressed  air. 
The  lamp  will  frequently  assist  in  locating  cavities  that  defy  the 
ordinary  methods  of  search,  and  the  compressed  air  is  valuable  in 
clearing  away  the  saliva  and  debris  and  giving  a  clear  field  for  inspec- 
tion. 

When  a  cavity  of  this  class  is  to  be  filled  it  is  the  invariable  practice 
to  fill  it  from  the  occlusal  surface,  making  it  a  proximo-occlusal  cavity. 


CLASS  II  CAVITIES  205 

This  is  for  the  double  purpose  of  making  the  extension  and  resistance 
forms  more  perfect  and  making  the  cavity  of  such  convenient  form  that 
the  gold  can  be  well  adapted  to  the  walls  of  the  same.  Fillings  made  by 
the  old  method  of  attempting  to  fill  the  cavity  by  making  a  simple 
proximate  cavity  failed,  because  there  was  a  recurrence  of  decay  around 
the  margins  that  were  not  brought  out  into  immune  territory.  The 
cavities  so  made  were  very  difficult  of  access  and  the  gold  was  imper- 
fectly adapted  to  the  walls  thereof,  so  that  the  fillings  leaked  and  there 
was  a  recurrence  of  decay  by  infiltration. 

Frequently  cavities  occurring  in  the  proximate  surface  of  a  bicuspid 
or  molar  are  complicated  by  the  presence  of  decay  starting  in  a  fissure 
in  the  occlusal  surface.  Whether  that  be  true  or  not  the  entrance  to 
the  cavity  is  through  the  occlusal  surface.  By  the  use  of  a  cross-cut 
or  dentate  fissure  bur  No.  702  an  entrance  is  made  through  the  enamel 
into  the  dentin  and  the  bur  is  made  to  travel  toward  the  margin  cutting 


Fig.   139. — Two  views  of  mesio-occlusal  cavity  in  Fig.  140. — Mesio-occlusal  cavity 

upper  first  bicuspid.  in  the  lower  first  bicuspid. 

into  the  dentin  and  drawing  it  up  through  the  enamel.  In  this  way  the 
enamel  is  undermined  and  its  organization  broken  up  to  such  a  degree 
that  the  breaking  down  of  the  same  is  a  very  easy  matter.  If  the  decay 
has  penetrated  into  the  dentin  from  the  proximate  surface  to  any  great 
extent  it  will  be  a  very  short  time  until  the  bur  will  fall  into  the  cavity, 
when  the  marginal  ridge  should  be  undermined  with  the  bur  cutting 
upward  at  the  same  time,  making  a  sweeping  motion  sideways  to  widen 
the  cavity.  When  sufficiently  undermined  the  marginal  ridge  should 
be  broken  down  by  the  use  of  chisel  No.  38  or  No.  39.  With  the  same 
bur  the  cavity  may  now  be  deepened  toward  the  gingival  by  cutting 
close  to  the  dento-enamel  junction  and  sweeping  the  bur  from  lingual 
to  buccal.  Cut  the  cavitj^  until  a  sufficient  gingival  depth  has  been 
obtained.  The  enamel,  being  undermined  by  this  operation,  can  be 
cut  away  easily  with  the  chisel  and  the  buccal  and  lingual  extensions 
obtained  in  the  sajne  way.     The  easiest  and  most  expeditious  niethod 


206     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

of  removing  the  enamel  is  to  place  the  edge  of  the  chisel  at  the  enamel 
margin  where  the  break  is  desired,  and  then  tap  the  end  of  the  chisel 
with  the  mallet.  If  the  enamel  has  been  properly  undermined  it  will 
be  very  easy  to  break  it  away  until  the  proper  outline  form  has  been 
obtained.  The  occlusal  step  should  be  made  by  the  use  of  the  inverted 
cone  bur  No.  37  or  No.  39  as  the  width  of  the  step  may  demand.  The 
outline  form  has  been  obtained  by  the  breaking  down  of  the  enamel 
under  the  chisel  and  mallet,  so  it  will  be  comparatively  easy  to  cut  the 
dentin  to  the  proper  depth  and  form.  The  depth  will  have  to  be 
gauged  by  the  amount  of  resistance  that  the  filling  will  have  to  with- 
stand, and  will  comprehend  one  of  the  points  of  the  resistance  form, 
which  we  should  now  have  in  mind.  If  it  has  been  ascertained  that 
there  is  a  strong  occlusal  force  that  will  probably  be  exerted  upon  the 
finished  filling,  it  will  be  necessary  to  make  the  cavity  correspondingly 
deep  and  broad.  If  it  is  to  be  a  deep  and  broad  preparation,  a  No.  39 
inverted  cone  bur  should  be  the  choice  and  the  floor  of  the  occlusal  step 
made  as  deep  as  necessary.  If  the  force  to  be  withstood  is  moderately 
great  a  depth  of  1|  mm.  will  usually  be  sufficient;  but  if  the  occlusion  is 
particularly  strong,  2  mm.,  and  in  rare  cases,  2J  mm.  will  be  permissible. 
In  making  the  resistance  form  in  the  occlusal  step  the  lines  of  the 
recession  of  the  pulp  should  be  in  mind  and  care  should  be  observed 
not  to  cut  through  these  lines  for  fear  of  cutting  into  a  prolongation  of 
a  horn  of  the  pulp,  in  which  case  the  destruction  thereof  would  be  an 
inevitable  consequence.  It  will  not  be  possible  to  give  a  study  of  the 
recessional  lines  of  the  pulp  in  this  treatise,  but  the  student  is  urged  to 
familiarize  himself  with  the  subject  so  that  he  may  avoid  the  distressing 
accidents  that  an  ignorance  thereof  will  inevitably  lead  him  into, 
namely,  exposure  of  the  pulp. 

When  the  cavity  depth  has  been  obtained  the  walls  should  be  made 
perpendicular  to  the  floor  and  should  be  as  nearly  parallel  to  each  other 
as  the  form  of  the  tooth  will  permit.  The  ideal  that  should  be  always 
before  the  operator  is  to  make  his  cavities  as  nearly  like  a  box  as 
possible  and  only  depart  from  that  as  the  anatomic  form  of  the  cavity 
and  the  exigencies  of  the  carious  process  may  demand.  Decay  does 
not  follow  any  hard  and  fast  lines,  and  while  the  ideal  should  always 
be  sought  it  must  be  borne  in  mind  it  may  not  always  be  attained. 
However,  with  an  ideal  in  mind  and  an  effort  for  its  attainment  one 
may  become  a  more  perfect  operator. 

The  squaring  out  of  the  cavity,  paralleling  of  the  walls,  etc.,  will  be 
most  easily  obtained  by  the  use  of  the  fissure  bur,  either  plain  or  dentate. 
After  the  walls  and  floor  have  been  roughly  squared  out  by  the  use  of 
the  burs  they  should  be  smoothed  by  the  use  of  the  hoe  No.  4  or  No.  5 
or  the  chisel  No.  29  or  No.  31. 


CLASS  II  CAVITIES  207 

The  gingival  wall  should  be  made  flat  by  the  use  of  the  inverted  cone 
bur  No.  37  or  No.  39  as  the  case  may  be,  the  choice  of  the  smaller  or 
larger  bur  being  determined  by  the  resistance  form  that  has  been 
chosen.  If  the  resistance  is  to  be  great  the  larger  bur  should  be  the 
choice,  but  if  the  seat  is  not  to  be  as  broad  as  that  contemplated  by  the 
use  of  the  larger  bur  then  the  No.  37  should  be  used.  The  idea  that 
is  to  be  in  the  mind  of  the  operator  all  the  time  is  to  make  the  cavity 
of  proper  proportions  and  adequate  strength.  The  buccal  and  lingual 
walls  are  to  be  made  perpendicular  to  the  step  and  parallel.  In 
the  linguo-gingivo-axial  and  bucco-gingivo-axial  angles,  convenience 
points  should  be  made  for  the  retention  of  the  first  pieces  of  gold, 
whether  the  cohesive  or  non-cohesive  methods  are  contemplated. 
These  points  are  made  by  allowing  the  shank  of  the  bur  to  follow  close 
to  the  bucco  or  linguo-axial  lines  and  then  letting  the  head  of  the  bur 
sink  into  the  gingival  point  angle.  The  angle  may  be  made  sharper  by 
the  use  of  the  33|  inverted  cone  bur  or  the  hand  instrument  No.  8  or 
No.  9.  These  instruments  are  primarily  intended  for  the  beveling  of 
the  cavo-surface  angle,  but  are  admirably  adapted  for  the  making  of 
point  angles  in  the  dentin. 

The  general  outline  of  the  resistance  form  and  retention  form  being 
made  by  the  use  of  the  bur,  it  is  well  to  smooth  up  the  cavity  by  the  use 
of  the  obtuse  angle  hoes,  going  all  over  the  dentin  with  a  planing 
motion  thus  making  a  smooth  and  beautiful  finish. 

In  making  a  proximo-occlusal  cavity  in  a  molar  or  bicuspid  we  have 
obtained  the  required  convenience  form,  for  no  angle  of  the  cavity  so 
made  is  placed  so  that  the  plugger  point  cannot  directly  reach  it  and 
the  condensation  of  the  gold  against  all  of  the  walls  of  the  cavity  is 
assured  if  the  operator  uses  the  right  technic  in  condensing  the  same. 

If  there  is  any  remaining  carious  dentin  it  must  be  removed,  after 
which  the  enamel  margins  should  be  finished.  This  means  that  all  of 
the  marginal  lines  should  be  squared  up.  The  lines  from  the  occlusal 
to  the  gingival  margins  should  be  made  as  straight  as  possible.  Par- 
ticular care  should  be  given  to  the  linguo  and  bucco-gingival  outline 
angles  to  see  that  they  are  well  out  of  the  embrasures.  These  are  the 
points  of  the  greatest  vulnerability  and  are  the  points  of  the  most 
frequent  failure  by  reason  of  a  recurrence  of  decay  around  the  margins. 
Because  of  the  fact  that  the  angles  have  been  rounded  off  or  allowed 
to  fall  so  far  within  the  embrasures  that  the  margin  of  the  filling  was 
within  the  area  of  susceptibility,  and  the  bacterial  plaques  were  there- 
fore enabled  to  fasten  themselves  upon  the  enamel  in  proximity  to  the 
filling,  a  new  point  of  decay  was  started  that  undermined  the  filling 
and  the  destruction  of  the  same  was  the  outcome.  To  prevent  such  an 
occurrence,  square  out  the  angles  of  the  cavity  to  such  an  extent  that 


208     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

they  will  be  in  immune  territory  and  no  fear  need  be  felt  of  a  failure  by 
reason  of  a  recurrence  of  decay  if  the  gold  has  been  properly  adapted. 

The  cavo-surface  angle  must  now  be  made,  and  at  the  gingival  margin 
in  an  upper  tooth  can  best  be  made  with  right  and  left  instruments 
designed  for  this  purpose,  Nos.  8,  9,  10  and  11.  These  margins  on 
the  proximate  surfaces  of  the  lower  molars  and  bicuspids  are  best 
made  with  the  Nos.  12  and  13  for  margins  on  the  distal  surfaces  and 
Nos.  14  and  15  for  margins  upon  the  mesio-gingival  surfaces.  The 
buccal  and  lingual  margins  can  be  made  with  the  chisels  Nos.  28,  29, 
30  and  31. 

The  cavo-sm-face  angle  upon  the  occlusal  surface  is  also  made  with  the 
chisel.  All  of  the  cavo-surface  bevel  for  the  gold  filling  is  made  at  an 
angle  of  from  10  to  15  centigrades  and  from  one-fourth  to  one-half  of 
the  thickness  of  the  enamel. 


Fig.  141. — Proximo-occlusal  cavity 
in  upper  molar,  showing  method  of 
protecting  a  weak  cusp,  by  cutting  off 
a  portion  and  restoring  with  gold  (a) 
mesio-buccal  cusp  cut  off. 


Fig.  142. — Mesio-occlu  so-distal  cavity  in 
bicuspids,  showing  method  of  strengthening 
weak  cusps. 


The  toilet  of  the  cavity  finishes  the  preparation  and  the  rubber  dam 
having  been  in  position  and  the  excavation  having  been  made  in  a  dry 
cavity,  there  is  usually  little  that  need  be  done.  A  blast  of  warm  air 
is  usually  sufficient,  but  if  not,  this  may  be  supplemented  by  going  over 
the  cavity  with  a  piece  of  cotton  or  spunk  in  the  pliers. 

If  the  carious  process  has  progressed  so  far  that  the  cusps  of  the  tooth 
are  undermined  or  weakened  by  the  near  approach  of  the  decay,  it  will 
be  necessary  to  protect  them  by  cutting  off  a  portion  of  the  cusps  and 
building  the  gold  over  them.  If  this  is  not  done  there  will  be  danger 
of  breaking  off  one  or  more  of  the  cusps.  This  is  particularly  true 
in  the  case  of  a  tooth  from  which  the  pulp  has  been  removed.  In 
the  event  that  it  is  thought  advisable  to  protect  them,  grind  off  a  portion 
of  the  cusp  or  cusps  as  may  be  thought  expedient.  The  amount  of  the 
tooth  to  be  removed  must  be  deterjuined  by  the  amount  of  decay  that 


CLASS  II  CAVITIES  209 

has  undermined  the  cusp  and  the  amount  of  stress  that  will  be  brought 
to  bear  upon  the  finished  filling.  It  should  always  be  enough  to  make 
room  for  a  sufficient  bulk  of  gold  to  stand  the  stress  of  mastication 
without  flowing.  A  sufficient  amount  of  the  enamel  should  be  removed 
to  bring  the  cavity  to  sound  tissue  supported  by  a  good  body  of  dentin. 
In  the  finishing  of  the  cavo-surface  angle  in  this  class  of  cases  the  bevel 
should  be  decided  and  of  sufficient  depth  to  make  for  a  goodly  flange  of 
gold  that  will  go  over  the  enamel  margin  and  effectually  bind  the  walls 
together.  If  the  cavity  is  so  made  and  the  amount  of  gold  that  over- 
lays the  walls  of  the  tooth  is  sufficient,  there  mil  be  little  danger  of  a 
fracture  of  the  tooth.  This  rule  is  one  that  should  be  followed  in  all 
cases  whether  the  cavity  occurs  in  a  bicuspid  or  a  molar.  It  is  also  of 
ec[ual  importance  to  protect  the  incisal  angles  of  incisors  and  cuspids  in 
case  of  a  like  weakness. 


a  be 

Fig.  143. — Three  views  of  mesio-occluso-distal  cavity  in  upper  first  bicuspid,    a,  mesia 
view;  b,  occlusal  view;  c,  distal  view. 

Cavities  involving  the  distal  and  mesial  surfaces  of  the  same  tooth 
are  restored  by  the  making  of  a  mesio-disto-occlusal  filling.  In  these 
cases  the  method  of  procedure  is  the  same  as  in  the  case  of  a  cavity 
occurring  in  either  the  mesio-occlusal  or  disto-occlusal  siu*face  of  a  tooth. 
The  outline  form  is  made  so  that  all  of  the  lines  of  the  cavity  are  in 
relatively  safe  territory,  while  the  resistance  and  retentive  forms  follow 
the  laws  of  flat  seats  and  parallel  walls.  The  only  difterence  in  the 
cavit}^  is  that  the  cavities  in  the  two  surfaces  of  the  tooth  are  treated  as 
one  and  filled  at  the  same  time. 

There  is  no  difference  in  the  principles  governing  the  preparation  of 
the  cavity,  whether  the  carious  process  occurs  in  a  lower  or  an  upper 
tooth.  There  is  a  difference  in  technic  due  to  the  location  of  the  tooth 
in  the  mouth  and  the  dissimilarity  of  approach.  In  the  making  of  a 
cavity  in  the  lower  molars  and  bicuspids  it  will  be  expedient  to  use  the 
14 


2l0    CAVITY  PREPARATION  AND  THE  EILLING  OF  TEETH 

contra-angle  hand  piece.  This  will  bring  the  bur  into  proper  relation 
to  the  tooth  to  make  the  advised  preparation.  The  walls  of  the 
cavity  and  the  internal  angles  can  best  be  cut  by  the  use  of  enamel 
hatchets  Nos.  22,  23,  24  and  25,  assisted  in  some  instances  by  the 
very  useful  angle  chisels  Nos.  32  and  33. 

As  indicated  above,  the  cavo-surf  ace  angle  of  the  gingival  margin  in 
the  lower  teeth  is  made  with  the  special  marginal  trimmers  Nos.  12,  13, 
14  and  15,  Nos.  12  and  13  being  for  the  angles  on  the  disto-gingival 
margins  and  Nos.  14  and  15  being  adapted  for  the  making  of  the  angle 
on  the  mesio-gingival  margins.  In  all  other  respects  the  cavities  are  the 
same  and  the  technic  identical  except  in  the  processes  enumerated. 


a  h 

Fig.  144. — Mesial  cavity  in  upper  central  incisor,     a,  labial  view;  b,  lingual  view. 

Class  O  Cavities.^ — Class  III  cavities  are  those  occurring  in  the  proxi- 
mate surfaces  of  the  incisors  and  cuspids  not  involving  the  angle.  The 
beginnings  of  the  decay  are  to  be  found  immediately  gingivally  to  the 
contact  point  and  should  be  discovered  at  the  earliest  possible  moment. 
There  is  very  little  excuse  for  these  cavities  attaining  any  appreciable 
size  in  the  teeth  of  patients  that  present  for  regular  examinations. 
Indeed,  there  is  little  excuse  for  a  cavity  in  any  surface  of  the  tooth 
making  much  headway  if  the  patient  is  conscientious  in  presenting  for 
examination  at  frequent  intervals.  But  while  there  might  be  some 
excuse  for  overlooking  an  incipient  cavity  in  the  proximate  surface  of 
the  second  or  third  molars  there  is  no  excuse  for  the  failure  to  discover 
a  cavity  beginning  in  the  proximate  surface  of  an  incisor  or  cuspid. 

In  the  treatment  of  Class  III  cavities,  the  rubber  dam  being  in  place, 
separation  must  be  made,  if  it  has  not  already  been  obtained.  A 
separator  of  the  Perry  or  Ivory  type  should  be  carefully  placed.  Too 
much  pressure  must  not  be  used  on  the  single  rooted  teeth  for  fear  of 
making  the  movement  so  great  and  sudden  that  permanent  injury  may 
be  done  to  the  peridental  membrane  or  pulp.  The  pressure  should  be 
applied  gradually  and  the  separator  tightened  as  the  tooth  moves  in  the 


CLASS  III  CAVITIES  211 

arch.  When  sufficient  separation  has  been  obtained  the  point  of  decay 
may  be  entered  with  a  No.  2  round  bur.  The  dentin  should  be  under- 
mined by  cutting  under  the  enamel,  after  which  with  chisel  No.  30 
the  enamel  wall  may  be  broken  down  to  the  extent  of  the  undermining 
thereof.  This  undermining  of  the  enamel  with  the  bur  and  breaking 
down  with  the  chisel  should  be  continued  until  the  desired  outline  form 
has  been  obtained.  This  form  contemplates  carrying  all  of  the  margins 
of  the  filling  out  of  the  areas  of  susceptibility  and  will  mean  that  the 
labial  margin  will  be  carried  labially  far  enough  out  of  the  embrasure 
to  prevent  the  enamel  coming  into  contact  with  the  enamel  or  filling 
in  the  approximating  tooth.  In  making  this  extension  it  is  not  neces- 
sary to  bring  the  gold  into  such  open  view  that  it  makes  a  glaring  defect. 
The  cutting  of  the  labial  portion  of  the  tooth  to  such  an  extent  that  it 
disfigures  the  patient  is  not  good  practice,  and  except  in  case  of  exten- 
sive decay  should  not  be  tolerated.  If  sufficient  separation  has  been 
obtained,  enough  room  to  perfectly  adapt  the  gold  to  the  walls  of  the 
cavity  can  be  obtained  without  a  disfiguring  restoration.  At  the  same 
time  the  extension  must  always  be  sufficient  to  cause  the  gold  to  clear 
contact  with  the  approximating  tooth  or  the  margin  will  lie  in  unclean 
and  therefore  susceptible  territory. 

The  gingival  margin  should  be  cut  far  enough  to  allow  the  gum  to 
cover  the  margin  of  the  finished  filling.  The  incisal  portion  should  be 
cut  far  enough  to  make  the  contact  on  the  gold  and  not  on  the  enamel. 
Lingually  the  margin  should  be  carried  out  far  enough  to  bring  it  clear 
of  the  approximating  tooth.  This  margin  should  be  rather  generously 
cut  for  the  reason  that  it  is  not  within  the  range  of  vision,  and  the 
further  reason  that  it  is  a  more  difficult  portion  of  the  filling  to  make  and 
by  more  extensive  cutting  a  greater  convenience  form  is  obtained. 

The  points  of  greatest  vulnerability,  and  therefore  the  areas  of  the 
greatest  number  of  recurrences  of  decay,  are  the  labio  and  linguo- 
gingival  angles.  The  reason  that  there  is  so  great  a  proportion  of 
recurrences  of  decay  in  this  territory  is  that  in  the  preparation  of  the 
cavities  these  angles  have  not  been  properly  squared-out.  It  is 
natural,  in  making  a  cavity  in  this  surface,  to  prepare  a  rounded  angle 
at  the  labio  and  linguo-gingival  angles  which  leaves  these  margins  so 
far  within  the  embrasures  that  they  are  not  kept  clean.  The  student 
should  emphasize  these  angles  to  such  an  extent  that  they  are  seemingly 
overprepared,  for  in  the  large  majority  of  cases  an  angle  that  looks 
to  him  as  though  it  was  too  far  out  of  the  embrasure  will,  when  filled, 
be  just  about  right,  with  the  probabilities  in  favor  of  the  fact  that  he 
has  not  cut  far  enough.  In  the  outline  form  of  a  cavity  in  the  incisal 
or  mesial  surface  of  the  cuspid  we  look  for  the  esthetic  form  more  than 
in  any  other  class  of  cavities,  for  here  more  than  any  other  place  does 


212    CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

the  filling  obtrude  itself  upon  the  consciousness  of  the  observer.  There- 
fore the  angles  that  are  within  the  range  of  vision  should  be  rounded. 
In  attempting  to  make  rounded  angles  the  student  is  led  into  the  greater 
error  of  not  bringing  them  out  far  enough,  and  it  will  take  much  time 
and  patient  observation  to  obtain  the  necessary  perfect  balance.  The 
angle  should  first  be  brought  out  sufficiently  far  for  purposes  of  safety, 
and  when  that  is  accomplished  the  squared  angles  should  be  gently 
curved  and  made  to  take  on  the  esthetic  form  of  outline.  This  is  not 
necessary  at  the  linguo-gingival  angle  but  must  be  made  a  matter  of 
routine  in  making  the  labial  angles  both  at  the  gingival  and  incisal. 

The  resistance  form  takes  the  form  of  the  squared  cavity.  The 
gingival  wall  should  be  made  flat  from  the  axial  wall  to  the  surface  of 
the  enamel,  but  labio-lingually  it  may  be  curved  to  harmonize  with  the 
outline  of  the  cemento-enamel  juncture.  The  round  bur  should  be 
discarded  as  soon  as  the  outline  form  has  been  obtained  and  should 
never  be  used  in  making  the  resistance  or  retentive  forms.  In  the 
class  under  discussion  the  best  bur  to  use  is  the  No.  35  or  No.  37 
inverted  cone. 

The  end  of  the  bur  should  be  used  in  making  the  flat  seat  at  the 
gingival  and  the  sides  of  the  bur  may  be  used  in  making  the  labial  or 
lingual  walls.  These  walls  should  be  as  nearly  at  right  angles  with  the 
gingival  seat  as  the  form  of  the  tooth  will  permit.  The  incisors  being 
of  a  wedge  form  a  cavity  in  the  proximate  surface  that  attempts  to 
conform  in  some  degree  to  the  shape  of  the  tooth  will  of  necessity 
take  the  form  of  a  triangle.  The  walls  of  the  cavity  will  therefore  con- 
verge as  they  approach  the  incisal  angle  and  the  finished  cavity  will  be 
triangular  in  shape.  The  axial  wall  should  be  made  to  conform  to  the 
shape  of  the  pulp;  the  labial  and  lingual  portions  of  the  same  being 
made  deeper  than  the  center,  that  the  pulp  may  have  all  the  protection 
of  dentin  that  is  possible.  The  angles  should  be  slightly  accentuated, 
and  this  may  be  accomplished  with  a  33|  inverted  cone  bur  and  the 
point  angles  then  sharpened  with  the  hand  instruments  Nos.  8  and  9. 
In  making  the  emphasized  angles  at  the  labio  and  linguo-gingivo- 
axial  angles,  there  is  usually  sufficient  convenience  point  to  start  the 
filling,  but  if  not,  it  is  permissible  to  make  a  convenience  point  for  the 
starting  of  the  gold  in  either  of  the  gingival  angles. 

The  labial  and  lingual  walls  may  be  cut  out  with  the  right  angle 
hoes  Nos.  6  and  7 .  The  point  angle  at  the  incisal  may  be  best  made 
with  the  33|  inverted  cone  bur.  In  making  the  cavity  of  the  shape 
suggested  we  have  satisfied  both  the  retentive  and  resistance  forms. 
The  convenience  form  is  very  important  in  this  class  of  cavities,  for  if 
the  operator  is  not  able  to  reach  all  parts  of  the  cavity  with  the  plugger 
point  he  will  be  unable  to  perfectly  adapt  the  gold  to  the  walls  of  the 


CLASS  IV  CAVITIES  213 

same,  and  in  this  situation  some  of  the  parts  of  the  cavity  may  be  very 
inaccessible  if  the  cavity  is  not  sufficiently  opened  up.  It  is  important, 
then,  at  this  stage  of  the  operation  to  determine  whether  all  parts 
of  the  cavity  are  accessible  to  the  plugger  point,  and  if  not,  to  cut 
away  enough  of  the  outline  to  make  the  cavity  convenient. 

The  enamel  margins  should  be  beveled  all  around  the  cavity.  The 
labial  and  lingual  margins  may  be  planed  with  a  chisel  and  the  bevel 
at  the  incisal  may  be  made  with  the  same  instrument.  The  gingival 
cavo-surface  angle  should  be  made  with  the  right  and  left  instruments 
Nos.  10  and  11.  The  toilet  of  the  cavity  is  made  by  removing  all 
debris,  carefully  searching  out  any  remaining  carious  dentin  and  the 
cavity  is  ready  to  fill. 

Class  IV  Cavities. — Cavities  of  the  fourth  class  are  those  occurring 
in  the  incisors  and  cuspids  involving  the  angle. 


a  be 

Fig.   145. — Mesio-incisal  cavity  in  upper  central  incisor,    a,  labial  view;  b,  mesio-distal 
longitudinal  section;  c,  lingual  view. 

This  class  of  cavities  is  more  difficult  to  fill  by  reason  of  the  fact  that 
in  the  loss  of  the  angle  so  much  of  the  tooth  has  been  destroyed  that  the 
problem  of  retention  is  considerably  intensified.  There  have  been 
several  ways  suggested  for  its  solution,  but  the  step  cavity  has  been  the 
best  in  practice  and  will  be  adhered  to  in  this  treatise.  The  outline 
form  will  be  obtained  by  breaking  down  all  overhanging  enamel  walls 
and  bringing  the  margins  of  the  cavity  into  sound  territory.  The 
problem  of  extension  for  prevention  is  usually  solved  by  the  progress 
of  the  decay,  for  if  the  angle  has  been  involved  it  is  more  than  probable 
that  the  tooth  has  decayed  so  far  that  the  finished  filling  will  have  its 
margins  in  safe  territory.  After  the  enamel  walls  have  been  trimmed 
down  the  incisal  portion  of  the  tooth  should  be  ground  with  a  flat 
carborundum  stone,  the  depth  and  extent  of  this  cutting  to  be  governed 
by  the  study  of  the  conditions  obtaining  in  the  special  case.     If  the 


214    CAVITY  PREPARATION  AND  THE  FILLING  OF  TEETH 

occlusion  is  great  there  will  be  the  necessity  for  a  considerable  trimming 
of  the  incisal  portion  of  the  tooth  in  order  to  allow  for  a  sufficient 
amount  of  gold  over  the  incisal  angle  to  withstand  the  stress  of  occlusion 
without  flowing.     It  is  obvious  that  the  least  cutting  that  can  be  done 
with  safety  should  be  the  ideal,  for  here,  more  than  in  any  other  place, 
will  the  gold  be  within  the  range  of  vision.     In  order  to  obviate  this 
difficulty,  operators  have  made  the  incisal  step  entirely  to  the  lingual, 
leaving  the  enamel  at  the  labial  surface  practically  intact;  but  the 
fallacy  of  this  preparation  has  been  proved  by  the  breaking  down 
of  the  unsupported  enamel  at  the  labial  or  the  infiltration  of  the 
filling  by  the  flowing  of  the  insufficient  mass  of  gold  over  the  incisal 
portion    of   the   filling.     In   this    place    we    will   have    to    sacrifice 
esthetics  for  utility  and  make  as  deep  and  broad  a  preparation  as  the 
case  demands  or  failure  will  result.     In  case  there  is  no  occlusion 
the  hiding  of  the  gold  by  making  nearly  all  of  the  step  to  the  lingual 
is  permissible,  but  if  the  opposing   incisors   are  able   to  come  into 
contact  with  the  incisal  portion  of  the  tooth  in  question  it  will  be 
imperative  to  cut  away  enough  of  the  labial  plate  to  allow  for  a  sufficient 
mass  of  gold  to  stand  up  under  stress.     The  amount  of  the  incisal  edge 
involved,  mesio-distally,  will  also  be  determined  by  conditions.    Usually 
it  will  be  necessary  to  cut  past  the  opposite  developmental  groove,  for 
in  making  the  incisal  step  it  will  nearly  always  be  necessary  to  carry 
it  past  the  middle  of  the  incisal  portion  of  the  tooth,  and  in  doing  so 
will  carry  the  margin  so  near  the  developmental  groove  that  the  margin 
of  the  cavity  will  be  in  weak  territory.     In  order  to  prevent  this  it  will 
be  found  advisable  to  carry  the  margin  past  the  groove  and  finish  it  in 
the  strong  enamel  beyond.     The  labial  portion  of  the  step  will,  in 
ordinary  cases,  be  cut  to  a  depth  of  1mm.  or  1|  mm.,  while  the  lingual 
portion  will  be  made  considerably  deeper.     The  lingual  portion  is  made 
deeper  for  several  reasons:     (1)  because  it  is  out  of  the  line  of  vision, 
it  may  be  cut  as  deep  as  desired  without  the  violation  of  any  esthetic 
ideal,  and  (2)  because  in  the  stress  of  mastication  the  lower  teeth  strike 
against  the  lingual  surface  of  the  upper,  and,  as  a  consequence,  the 
greater  mass  of  gold  is  required  at  that  point.     The  incisal  third  of 
incisors  and  cuspids  is  almost  entirely  composed  of  enamel,  due  to  the 
convergence  and  union  of  the  labial  and  lingual  enamel  plates.     There- 
fore, in  order  to  provide  sufficient  width  of  dentin  labio-lingually,  to 
properly  prepare  a  step,  it  is  necessary  to  sacrifice  one  or  both  plates  of 
enamel.     Since  the  preservation  of  the  labial  plate  is  desirable  for 
esthetic  reasons,  the  lingual  plate  is  cut  far  enough  to  provide  sufficient 
dentin  in  which  to  anchor  the  filling.    The  outline  form  being  completed, 
the  resistance  and  retentive  forms  should  be  made.     The  gingival  wall 
is  made  as  flat  as  the  nature  of  the  case  will  allow.    In  incisors  and 


CLASS  IV  CAVIfiSS  215 

cuspids,  as  has  been  said,  it  is  permissible  to  follow  the  cemento- 
enamel  curve,  which  will  cause  the  filling  to  seat  upon  the  convex  side 
of  an  arch,  which  in  mechanics  is  unobjectionable,  especially  when 
there  is  not  the  tremendous  stress  that  will  be  brought  to  bear  upon 
a  filling  in  a  molar  or  bicuspid.  On  the  other  hand,  if  we  insisted  on 
making  the  gingival  seat  flat  in  the  incisors  and  cuspids  we  would  often 
find  that  we  would  run  into  the  cementum  and  perhaps  the  peridental 
membrane  in  the  central  portion  of  the  cavity  when  we  were  trying  to 
bring  the  labio  and  linguo-gingival  angles  into  safe  territory,  for  there 
is  frequently  so  great  a  curve  of  the  cemento-enamel  line  that  it  is  carried 
down  into  the  embrasure  so  far  that  a  flat  seat  for  the  filling  that  would 
not  endanger  this  line  would  tend  to  make  a  very  shallow  linguo  and 
labio-gingival  angle.  Therefore  it  is  the  part  of  wisdom  to  curve  the 
gingival  wall  labio-lingually  in  incisors  and  cuspids,  so  that  it  will  in 
some  degree  conform  to  the  curve  of  the  cemento-enamel  line. 

This  step  is  best  obtained  by  the  use  of  inverted  cone  burs  Nos.  35 
and  37,  according  to  the  size  of  the  tooth  being  operated  upon.  The 
proximate  walls  will  be  made  triangular  with  the  base  to  the  gingival 
and  the  apex  toward  the  incisal.  These  walls  should  be  as  nearly  at 
right  angles  to  the  gingival  step  as  the  form  of  the  tooth  will  permit, 
having  them  converge  as  they  approach  the  incisal.  At  the  inciso- 
proximate  angle  the  cavity  will  pass  into  the  incisal  portion  in  a  groove 
cut  into  the  dentin  between  the  labial  and  lingual  enamel  plates.  This 
groove  should  not  be  very  deep  and  should  not  cut  into  the  enamel. 
It  should  be  confined  entirely  to  the  dentin  and  some  dentin  should  be 
left  on  either  side  to  protect  the  enamel.  After  passing  the  site  of  the 
recessional  line  of  the  pulp  a  pit  is  sunk  into  the  dentin  for  a  slight 
distance  to  help  resistance  to  lateral  displacement.  The  groove  in  the 
incisal  portion  of  the  cavity  should  be  made  with  a  small  inverted  cone 
bur,  usually  a  No.  35  in  an  upper  incisor  or  cuspid.  The  pit  may  be 
made  with  the  same  instrument  and  rendered  slightly  retentive  by 
undercutting  to  some  extent.  The  linguo  and  labio-gingivo-axial 
point  angles  should  be  definitely  emphasized,  for  upon  them,  to  a  great 
extent,  depends  the  retentive  form  of  the  cavity.  These  angles  should 
be  made  in  the  same  way  as  those  in  the  corresponding  angles  in  Class  II 
cavities  in  bicuspids  and  molars.  The  angles  are  made  with  a  No.  35 
inverted  cone  bur  and  accentuated  with  the  instruments  Nos.  8  and  9. 
If  desired  a  convenience  point  may  be  made  in  the  linguo-gingivo-axial 
angle,  but  the  making  of  the  retentive  angles  is  usually  suflacient  for  the 
purpose  of  starting  the  filling.  The  shape  of  the  incisal  step  cavity  is 
such  that  no  more  convenience  form  is  needed,  so  it  will  not  be  neces- 
sary to  elaborate  upon  that.  Any  remaining  decay  should  be  carefully 
removed,  the  cavo-surface  angle  beveled  all  around  the  margins  with 


216     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

the  usual  hand  instruments,  the  toilet  of  the  cavity  made  and  the 
cavity  is  ready  for  the  filling. 


Fig.    146. — Mesio-incisal  cavity,  upper 
cuspid. 


Fig.   147. — Disto-incisal  cavitj-,  upper 
cuspid. 


In  proximate  cavities  occurring  in  the  distal  surfaces  of  cuspids  it  is 
very  difficult  to  perfectly  adapt  the  gold  to  the  walls  of  a  cavity  made. 


d  e  f 

Fig.    148. — Gingival  cavities,     a,  upper  cuspid;  b,  upper  central;  c,  lower  cuspid; 
d,  lower  first  molar;  e,  lower  second  molar;  /,  lower  third  molar. 


as  is  usual  in  CUass  II.     Therefore,  some  of  our  best  operators  have 
suggested  making  all  such  cavities  into  Class  IV,  intentionally  involving 


CLASS  V  CAVITIES  217 

the  angle  and  making  a  step  in  the  incisal  surface.  They  do  this  for 
the  purpose  of  making  the  cavity  of  sufficient  convenience  that  the  gold 
may  be  perfectly  adapted  to  it,  rightly  believing  that  it  is  wise  to  cut 
away  sound  tooth  structure  that  the  rest  of  the  tooth  may  be  saved 
with  a  filling  rather  than  attempt  to  save  a  portion  of  the  remaining 
healthy  tooth  structure,  and  by  so  doing  lose  the  whole  tooth  by  a 
recurrence  of  decay,  because  a  perfect  filling  was  not  made  by  reason 
of  the  difficulty  of  adaptmg  the  gold  to  a  surface  that  was  not  -within 
the  reach  of  the  plugger  point. 

In  making  this  cavity  the  same  rules  and  technic  are  followed  as 
outlined  for  a  step  cavity  in  an  incisor. 

Class  V  Cavities. — Cavities  occurring  in  the  gingival  third  of  any  of 
the  teeth  are  Class  A'  cavities.  The  placing  of  the  dam  in  this  class  is 
sometimes  very  difficult.  Especially  is  this  true  if  the  decay  has  pene- 
trated very  far  beneath  the  surface  of  the  gum,  as  is  frequently  the  case 
in  advanced  cases.  In  order  to  place  the  dam  properly  it  will  be  neces- 
sary to  have  a  special  clamp  to  push  the  gum  back  and  to  hold  the  rubber 
in  place.  There  are  several  good  clamps  on  the  market.  If  the  decay  has 
not  penetrated  very  far  an  ordmary  gingival  clamp  of  the  Ivory  tx'pe  may 
be  used  effectively.  The  Hatch  and  Woodward  clamps  are  well  adapt- 
ed for  cavities  in  which  it  is  necessary  to  retract  the  gum  in  order  to 
gain  access.  The  Ivory  clamp  is  a  very  superior  clamp  for  this  purpose. 
It  is  adjustable  and  is  provided  with  a  movable  gum  retractor  that  is 
actuated  by  a  screw  with  which  the  gum  may  be  pushed  back  at  will 
as  far  as  the  operator  desires.  It  is  advisable  to  use  an  anesthetic 
in  cases  where  there  is  any  considerable  retraction  of  the  gum  for  the 
pain  of  the  operation  is  intense.  A  local  anesthetic  used  upon  the 
gum  prior  to  the  operation  will  obviate  all  this  and  make  a  very  trying 
operation,  one  that  w]\\  be  bearable. 

When  the  dam  has  been  placed  and  the  field  of  operation  cleansed,  the 
cavity  may  be  opened  with  a  spoon  excavator  and  all  of  the  decay 
removed.  In  case  it  is  a  cavity  in  its  incipiency  it  will  be  necessary  to 
open  it  up  ^-ith  a  bur,  when  it  is  wise  to  use  a  No.  3  or  Xo.  4  romid  bur. 
With  this  instrument  excavate  under  the  enamel  imtil  the  walls  may 
be  chiseled  to  the  desired  outline  form.  The  axial  wall  of  the  ca^■ity 
may  now  be  flattened  -^-ith  an  inverted  cone  bur  of  the  proper  size, 
and  ■s\'ith  the  same  instrument  the  walls  may  be  made  parallel.  The 
general  shape  of  the  cavity  should  harmonize  T^-ith  the  festoon  of  the 
gum,  ca^r^'ing  the  mesial  and  distal  portions  to  the  angles  of  the  tooth. 
The  gingival  margm  should  be  placed  well  imder  the  free  margm  of  the 
gum,  and  the  portion  of  the  cavity  looking  toward  the  occlusal  siu-face 
of  the  tooth  brought  as  far  occlusally  as  will  be  necessary  to  obtain  the 
scouring  action  of  the  bokis  as  it  passes  over  the  teeth  in  mastication. 


218    CAVITY  PREPARATION  AND  THE  FILLING  OF  TEETH 

As  has  been  said,  this  will  differ  in  teeth  of  varying  shapes,  the  bell- 
shaped  tooth  requiring  a  greater  extension  occlusally  than  a  flat  tooth 
occluso-gingivally,  for  the  reason  that  in  the  bell-shaped  tooth  the  bell 
will  cause  the  bolus  to  leave  the  tooth  a  little  beyond  the  middle  third 
and  the  gingival  third  will  not  receive  any  of  the  scouring  action.  It 
will  be  wise  to  study  the  shape  of  the  tooth  in  order  to  see  how  far  occlus- 
ally it  will  be  necessary  to  carry  the  extension.  In  cases  of  any  con- 
siderable decay  there  will  usually  be  a  well-defined  line  of  demarcation 
showing  where  the  frictional  action  of  the  food  in  mastication  ceases. 
Cut  a  little  beyond  this  white  line  and  the  cavity  will  usually  be  in  safe 
territory. 

The  general  shape  of  the  cavity  will  be  of  a  half-moon  with  blunt 
edges,  and  the  internal  shape  will  be  a  flat  seat  and  box-like  walls.  A 
convenience  point  may  be  made  in  the  disto-gingivo-axial  angle  for  an 
aid  in  starting  the  gold.  The  cavo-surface  angle  bevel  should  be  made 
all  around  the  cavity,  not  so  much  for  the  protection  of  the  enamel 
rods,  for  in  this  class  of  cavities  there  will  be  very  little  stress  upon 
them,  as  to  be  sure  that  the  enamel  margins  are  sound  and  that  there 
are  no  loose  rods  lying  upon  the  surface  of  the  cavity.  The  toilet  of 
the  cavity  should  now  be  made,  assuring  one's  self  at  the  same  time 
that  all  remaining  decay  has  been  removed. 

FILLING  TEETH  WITH  GOLD. 

There  are  two  kinds  of  gold  used  in  filling  cavities  in  teeth — gold  foil 
and  the  various  makes  of  crystal  gold. 

The  foil  comes  in  the  cohesive  and  non-cohesive  forms  and  is  used  in 
pellets,  ribbons,  cylinders  and  ropes. 

The  cohesive  gold  is  pure  gold  with  an  uncontaminated  surface. 
Gold  is  a  metal  that  does  not  oxidize  when  pure,  and,  consequently, 
its  portions  being  in  the  pure  and  uncontaminated  state  will  cohere. 
If  any  contamination  adheres  to  the  surface  of  the  gold  it  becomes 
non-cohesive;  therefore,  the  operator  heats  it  before  using  to  drive 
off  any  moisture  or  volatile  substance  that  may  have  adhered  to  its 
surface,  or  may  have  been  placed  upon  it  by  the  manufacturer. 

There  are  two  kinds  of  non-cohesive  gold:  that  which  is  made  tem- 
porarily non-cohesive  by  the  deposition  upon  its  surface  of  some 
volatile  substance  and  the  permanently  non-cohesive  gold,  that  is  so 
made  by  the  deposition  upon  its  surface  of  a  substance  that  is  not 
driven  off  by  heat,  and,  as  a  consequence,  retains  its  non-cohesive 
properties  despite  any  heating  that  may  be  given  it.  We  prefer 
that  which  is  made  non-cohesive  by  the  deposition  of  some  volatile 
substance  for  the  reason  that  we  may  use  the  same  gold  for  non- 


PILLING  TEBlTH  WITH  GOLD  219 

cohesive  and  cohesive  filUngs  as  it  suits  our  purpose,  depending  upon 
whether  or  not  we  heat  it.  When  this  gold  has  not  been  heated  it  is 
in  the  non-cohesive  form,  and  when  desired  in  the  cohesive  form  it  is 
only  necessary  to  heat  it. 

This  form  of  non-cohesive  foil  is  usually  made  by  subjecting  the  gold 
to  the  fumes  of  ammonia  gas,  which,  being  deposited  upon  the  surface 
of  the  gold,  prevent  the  particles  of  gold  from  coming  into  perfect 
contact  and  thereby  prevent  cohesion. 

There  are  certain  substances  that,  when  condensed  upon  the  surface 
of  gold,  defy  the  power  of  heat  to  dispel  them,  and  thus  make  the  gold 
permanently  non-cohesive,  a  quality  that  is  sometimes  taken  advantage 
of  by  the  manufacturers  of  the  permanently  non-cohesive  types.  Some 
of  these  substances  may  be  deposited  upon  the  gold  as  it  lies  in  the 
cabinet  or  upon  the  operating  tray.  The  fact  that  this  does  occur  is 
attested  by  the  occasions  when  we  find  that  it  is  impossible  to  make  a 
certain  pellet  of  gold  cohere  to  that  placed  upon  the  filling,  or  when  we 
find  that  the  filling  becomes  flaky  and  the  pellets  fail  to  properly  cohere. 
That  is  the  reason  that  an  experienced  operator  uses  nothing  but  freshly 
prepared  gold  in  his  cohesive  fillings,  knowing  from  experience  that  if 
he  does  not  he  will  invite  failure  by  having  the  gold  fail  to  properly 
weld.  Therefore  we  advise  the  use  of  the  non-cohesive  or  so-called 
soft  gold.  The  name  soft  gold  is  a  misnomer,  as  all  pure  gold  that  is 
annealed  is  soft.  Gold  becomes  soft  by  annealing  and  hard  by  beating 
or  rolling;  therefore,  the  cohesive  gold  is  just  as  soft  as  the  non-cohesive 
when  it  is  annealed.  The  reason  that  the  non-cohesive  gold  is  called 
soft  is  because  the  old  operators  used  the  gold  in  the  non-cohesive 
forms,  and  when  it  became  cohesive  it  was  hard  to  use  in  the  way  in 
which  they  were  accustomed  to  use  it.  The  non-cohesive  form,  by 
reason  of  its  non-cohesive  qualities,  worked  more  easily  and  seemed 
soft  under  the  instruments  in  contradiction  to  the  harsh  properties  of 
the  cohesive  gold  sticking  to  the  gold  in  the  cavity  and  preventing  the 
newly  placed  gold  from  going  easily  to  position.  The  names  soft  and 
cohesive  came  from  that  source,  but  should  now  be  discarded  for  the 
better  terms,  heated  and  unheated  or,  if  preferred,  cohesive  and  non- 
cohesive.     We  find,  therefore,  that  we  have  two  kinds  of  soft  foil: 

(1)  non-cohesive  foil,  that  which  cannot  be  made  cohesive  by  heating; 

(2)  non-cohesive  foil,  that  which  can  be  made  cohesive  by  heating. 
Both  of  these  foils  are  called  soft,  but  the  first  remains  soft  after  heating, 
while  the  second  becomes  cohesive  or  hard  after  heating.  For  this 
reason  we  divide  the  non-cohesive  foils  into  two  divisions  as  follows: 
unheated — soft  foil — non-cohesive,  and  heated — soft  foil — cohesive. 

The  non-cohesive  is  advised,  because  it  has  its  surface  protected  by  a 
film  of  volatile  gas — usually  ammonia — which  prevents  the  deposition 


220     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

upon  its  surface  of  any  contaminating  substance  that  would  make  it 
permanently  non-cohesive  and  would  make  a  fault  in  the  filling  of  which 
it  became  a  part.  The  ammonia  remains  upon  the  gold  until  it  is 
ready  for  the  filling,  when,  upon  being  heated,  it  is  driven  off  and  a 
perfectly  pure  fresh  surface  of  the  gold  is  presented  for  cohesion  with 
that  in  the  cavity  and  that  which  is  to  follow  it  in  the  filling,  making 
for  perfect  cohesion  and  the  possibility  of  a  dense  filling. 

In  preparing  the  pellets  for  use  in  making  a  cohesive  filling  we  use  the 
No.  4  non-cohesive  or  soft  foil.  This  comes  in  books  of  foil.  The 
pellets  are  prepared  in  eighths,  sixteenths,  thirty-seconds  and  sixty- 
fourths.  By  this  we  mean  that  a  sheet  of  gold  is  taken  and  divided 
into  eight  parts  and  rolled  into  pellets,  each  pellet  containing  an  eighth 
of  a  sheet  of  gold.  Likewise  a  sixteenth  pellet  is  one  containing 
one-sixteenth  of  a  sheet  of  gold,  a  thirty-second  is  a  pellet  contain- 
ing one-thirty-second  of  a  sheet  of  gold,  etc.  This  is  done  in  order 
that  we  may  definitely  know  the  amount  of  gold  under  our  plugger 
point  at  any  particular  time.  Definite  methods  produce  definite  results, 
therefore  we  choose  to  know  the  amount  of  gold  that  we  are  using  at 
any  given  time,  so  that  we  may  know  the  amount  of  force  that  will  be 
required  to  condense  the  gold  to  a  required  specific  gravity.  If  we  did 
not  know  the  amount  of  gold  we  were  condensing  we  would  not  be  sure 
of  the  method  we  were  using  and  could  not  be  sure  that  we  were  produc- 
ing the  desired  result. 

The  various  forms  of  crystal  gold  in  the  market  are  cohesive  and 
have  no  particular  advantage  over  the  foil.  In  the  opinion  of  the 
authors  they  are  not  so  good,  but  excellent  fillings  may  be  made  with 
them  if  the  same  care  is  taken  in  condensing  as  that  given  to  the  foils. 
The  reason  that  so  many  failures  of  condensation  and  pitted  fillings  are 
made  with  the  crystal  foil  is  not  the  fault  of  the  gold  primarily  but  of 
manipulation.  It  requires  as  much  force  to  condense  the  crystal  golds 
as  it  does  the  foils;  indeed,  in  Dr.  Black's  laboratory  it  was  found  that 
it  really  required  more  force  to  obtain  the  same  specific  gravity  with  a 
crystal  gold  than  it  did  with  a  foil.  If,  however,  the  operator  is  not 
misled  by  the  belief  that  a  perfect  filling  can  be  made  without  the 
expenditure  of  much  condensing  force,  and  uses  the  same  mallet  pres- 
sure upon  a  filling  made  with  crystal  gold  that  he  uses  in  making  a 
foil  filling,  he  will  be  able  to  make  a  good  filling. 

The  foil,  for  use  as  a  non-cohesive  gold,  must  have  an  entirely  dif- 
ferent treatment,  for  here  we  will  have  to  depend  upon  the  mechanical 
retention  of  the  gold  without  any  assistance  of  the  coherence  of  the  gold 
itself.  In  making  a  non-cohesive  filling,  in  whole  or  in  part,  this  fact 
must  be  ever  in  mind,  that  we  must  not  depend  upon  the  coherence  of 
the  gold  to  help  in  the  retention  of  the  filling. 


FILLING  TEETH  WITH  GOLD  221 

Non-cohesive  foil  is  used  in  cylinders,  ribbons  and  ropes,  but  in  this 
treatise  only  the  cylinders  will  be  considered,  because  the  other  forms 
are  unnecessary  and  will  only  confuse  the  student  if  elaborated  upon. 

The  cylinders  are  used  in  whole  sheets,  half  sheets,  quarter  sheets  and 
eighth  sheets.  They  are  made  by  taking  a  sheet  of  non-cohesive 
gold  and  dividing  it  into  the  number  of  parts  required  for  the  size  of 
cylinder  wanted.  If  it  is  to  be  a  half  sheet  cylinder  the  sheet  of  gold  is 
divided  into  two  parts.  One-half  of  the  sheet  is  taken  and  made  into 
a  ribbon  by  folding  the  gold  upon  itself  a  sufficient  number  of  times 
to  make  a  ribbon  of  the  width  we  want  the  length  of  the  finished 
cylinder  to  be.  In  our  operations  we  will  want  a  number  of  different 
length  cylinders  according  to  the  depth  of  the  cavity  upon  which  we  are 
operating.  Knowing  the  length  of  the  cylinder  we  will  want,  the  ribbon 
will  be  made  to  conform  to  that  width.  The  ribbon  of  gold  is  now  taken 
and  rolled  upon  the  end  of  a  Swiss  broach  or  long  pin  of  some  kind. 
A  Swiss  broach  is  more  useful  because  the  instrument  is  not  round  but 
triangular  in  shape  and  the  gold  will  roll  better  upon  it  because  the 
angles  of  the  broach  will  engage  with  the  gold  and  hold  it  from  slipping 
while  the  rolling  process  is  going  on.  If  a  smooth  instrument  be  used 
the  gold  will  have  a  tendency  to  slip  and  it  will  be  difficult  to  make  a 
cylinder.  The  cylinder  should  not  be  too  tightly  rolled,  nor  so  loosely 
rolled  that  it  will  not  maintain  itself  as  a  cylinder  and  unroll.  The 
ends  of  the  cylinder  should  be  smoothed  by  holding  the  cylinder  in  the 
hands  and  slightly  pressing  in  the  ends  between  pliers.  In  this  way  a 
smooth  symmetrical  cylinder  may  be  made.  If  much  operative  work 
is  done  it  is  well  to  have  an  assortment  of  soft  gold  cylinders  of  various 
sizes  and  pellets  of  cohesive  gold  made  up  ready  for  use.  In  case  an 
assistant  is  available  it  is  wise  to  make  the  preparation  of  the  gold 
a  part  of  her  duties. 

In  the  use  of  the  non-cohesive  foil  for  fillings  we  may  use  it  alone  or  in 
combination  with  the  cohesive  foil.  If  it  is  used  alone  the  cavity 
should  be  of  box  form  with  four  sides.  The  ideal  cavity  for  the  use  of 
non-cohesive  gold  is  one  in  the  occlusal  surface  of  one  of  the  molars. 
The  preparation  of  the  cavity  is  no  different  from  that  in  which  the 
cohesive  gold  is  used. 

For  example,  let  us  fill  a  cavity  of  the  occlusal  surface  of  a  lower 
molar.  A  half  sheet  cylinder  is  placed  on  end  in  the  distal  portion  of 
the  cavity  and  pressed  to  place  with  a  large  foot  plugger.  In  this 
position  the  cylinder  is  placed  on  end,  one  end  resting  on  the  dentin  of 
the  pulpal  wall  of  the  cavity  and  the  other  extending  out  of  the  cavity. 
The  cylinder  should  be  long  enough  to  extend  out  of  the  cavity  1  mm. 
or  1|  mm.  The  cylinder  is  made  to  rest  on  end  because  the  leaves  of 
gold  have  no  cohesion  and  will  therefore  not  cohere  to  each  other.     If 


222     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

we  placed  the  cylinder  on  its  sides,  with  one  of  the  sides  extending  out 
of  the  cavity,  the  leaves  of  the  cylinder  would  peel  off  and  the  filling 
would  in  that  way  disintegrate;  but  if  placed  on  end  the  sides  of  the 
cylinder  will  be  held  in  place  by  the  other  cylinders  that  are  wedged 
in  place  against  it. 


Fig.   149. — Cavity  in  lower  molar  pre- 
pared for  non-cohesive  gold  filling. 


Fig.  150. — Same  cavity  with  cylinder 
in  place  in  distal  portion  of  same. 
Cylinder  standing  on  end. 


The  first  cylinder  is  followed  by  other  cylinders  placed  on  end  coming 
forward  to  the  center  of  the  cavity  when  a  cylinder  is  placed  in  the 
buccal  and  lingual  angles.  It  will  now  be  advisable  to  place  a  cylinder 
in  the  mesial  angle  of  the  cavity  and  thereby  have  the  walls  of  the 
cavity  entirely  filled,  leaving  an  opening  in  the  center.  The  cylinders 
should  be  condensed  toward  the  walls  of  the  cavity  all  around,  using 


Fig.   151.— Cavity  half  fiUed. 


Fig.  152. — ^Cavity  filled  with  the  excep- 
tion of  the  key  cylinder  which  is  illustrated 
beside  the  tooth. 


hand-pressure  and  a  strong  wedge-shaped  plugger.  Keep  on  filling 
around  the  sides  of  the  cavity  until  it  is  impossible  to  introduce  any 
more  of  the  half  cylinders  into  the  center.  By  the  wedging  process  a 
small  opening  will  be  left  in  the  center  that  should  be  as  deep  as  possible 
and  into  this  opening  a  tightly  rolled  half  or  eighth  cylinder  is  forced 


FILLING  TEETH  WITH  GOLD 


223 


to  place,  and  the  entire  occlusal  surface  is  now  malleted  with  strong 
mallet-pressure.  In  this  way  the  whole  mass  of  gold  is  thoroughly 
condensed  and  the  cylinders  wedged  together,  keying  the  whole  mass 
to  place,  and,  though  there  is  no  cohesion  of  the  gold,  by  wedging  the 
cylinders  tightly  into  a  box-like  cavity  they  are  so  thoroughly  locked 
into  it  that  it  is  impossible  for  them  to  become  dislodged.     This  form 


Fig.   153. 


-Cavity  full  of  cylinders  but 
not  condensed. 


Fig. 


154. — Gold  condensed  by  hand 
matlet. 


of  a  filling  makes  one  of  the  best  fillings  that  can  possibly  be  made,  and 
many  of  those  made  by  the  great  operators  of  the  past  are  still  doing 
splendid  service.  The  only  difficult  part  of  this  operation  is  the 
making  of  the  central  key,  and  this  difficulty  is  obviated  by  the  use 
of  cohesive  gold  to  make  the  center  wedge.  Into  the  opening  that  is 
left  in  the  center  of  the  cavity,  introduce  a  pellet  of  heated  gold,  which 


Fig.   155. — Finished  filling. 


makes  it  cohesive,  mallet  this  to  place  and  fill  the  central  opening  full 
of  the  cohesive  gold,  and  then  mallet  the  entire  surface  of  the  gold  as 
though  it  were  all  non-cohesive  foil.  A  filling  that  would  require  a 
long  and  tedious  operation  may  be  made  in  a  very  short  time  and 
accomplished  much  more  effectively  than  could  be  done  by  the  use  of 
cohesive  foil  alone. 


224     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

Another  place  where  the  non-cohesive  foil  is  of  great  advantage  is  in 
the  gingival  thirds  of  cavities  in  the  proximate  surfaces  of  bicuspids 
and  molars.  Three  cylinders  are  usually  used  and  should  be  of  the 
proper  size  to  fit  the  cavity.  In  a  fairly  large  cavity  in  a  molar  we  would 
use  two  cylinders  of  half-sheet  each  in  the  angles  and  one  of  quarter- 


FiG.  1 56. — Cavity  in  proximate  surface  of  bicuspid 
ready  for  gold  filling. 


Fig.  157. — Non-cohesive  cyl- 
inders in  bucco  and  linguo- 
gingival  angles. 


sheet  in  the  center.  The  cylinders  having  been  selected,  one  of  the 
halves  is  taken  in  the  pliers,  slightly  compressed  and  firmly  tucked  into 
the  linguo-gingivo-axial  angle;  then  the  other  half  is  in  like  manner 
placed  into  the  angle  on  the  buccal  surface  and  between  these  two 
cylinders  is  firmly  wedged  the  quarter  sheet  cylinder  of  the  non- 
cohesive  gold.     The  three  cylinders  should  now  be  condensed  with 


Fig. 


158.  — ■  Central  cylinder  keyed  in 
between  the  two  cylinders. 


Fig.  159. — Cohesive  foil  beginning  to 
be  built  over  the  cylinders,  note  foil 
built  in  step. 


hand  pressure,  being  careful  not  to  push  them  out  of  the  cavity.  They 
will  be  held  in  place  by  the  approximating  tooth,  but  can  be  dislodged 
easily  by  pressure  exerted  in  the  wrong  direction.  The  gingival  portion 
of  the  cavity  is  now  filled  and  the  operation  has  been  accomplished  in  a 
quarter  of  the  time  that  would  have  been  necessary  to  condense  cohesive 


FILLING  TEETH   WITH   GOLD 


225 


gold  into  the  same  place  and  the  adaptation  of  the  gold  to  the  walls 
of  the  cavity  is  as  nearly  perfect  as  it  is  possible  to  make  it. 

The  filling  should  be  completed  with  cohesive  foil.  Begin  the  filling 
by  starting  a  pellet  of  heated  foil  in  one  of  the  angles  at  the  distal  of 
the  occlusal  step.  The  foil  may  be  heated  in  several  ways:  it  is 
possible  to  heat  over  the  open  flame,  using  for  that  purpose  a  flame 


Fig.  160. — Foil  in  step  built  over  the 
edge  of  the  step  and  uniting  with  gold 
built  over  non-cohesive  cylinders. 


Fig.  161. — Building  of  cohesive  foil 
finished  but  non-cohesive  cylinders  not 
condensed. 


in  which  the  combustion  is  perfect  and  in  which  the  gas  burns  with  a 
perfectly  blue  flame.  The  slightest  evidence  of  imperfect  combustion 
is  cause  to  reject  the  flame,  for  the  products  of  the  imperfect  combustion 
will  be  deposited  upon  the  gold  and  will  prevent  a  perfect  cohesion,  and 
a  flaky  filling,  or  one  that  will  break,  will  be  the  result.  It  is  better 
not  to  use  the  open  flame  for  heating  at  all.     Use  either  a  mica  or  por- 


Fig.   162. — Non-cohesive  cylinders 
condensed. 


Fig.   163.— Finished  filHng. 


celain  plate  over  the  flame,  upon  which  the  gold  may  be  placed  and 
heated  as  the  operator  proceeds  with  the  filling.  The  best  heater  is 
the  electric,  for  with  this  there  is  plenty  of  heat  to  perfectly  dissipate 
the  gaseous  deposit  placed  there  for  the  protection  of  the  gold  and 
prepare  it  for  perfect  cohesion,  and  there  is  no  danger  of  the  contami- 
nation of  the  gold  by  the  products  of  imperfect  combustion. 
15 


226     CAVITY  PREPARATION  AND  THE  FILLING  OF  TEETH 

The  first  pellet  having  been  placed  is  malleted  to  adaptation  and  the 
next  built  upon  it. 

There  are  several  methods  of  condensing  gold:  the  hand  mallet  in 
the  hands  of  a  trained  assistant,  the  hand  mallet  used  by  the  operator 
himself,  the  automatic  plugger,  the  pneumatic  engine  and  the  electric 
mallets.  Each  one  of  these  has  its  advocates,  and  operators  trained 
in  the  use  of  the  different  mallets  obtain  splendid  results  with  any  of 
them;  but  the  hand  mallet  in  the  hands  of  a  trained  assistant  holds 
first  place  in  the  opinion  of  the  authors.  With  it  the  amount  and  direc- 
tion of  force  may  be  more  easily  and  certainly  adapted  to  the  purpose 
of  condensation  than  with  any  other.  In  case  the  student  does  not  have 
an  assistant  he  may  choose  the  automatic  plugger  or  use  the  hand  mallet 
himself,  if  he  trains  himself  thoroughly  in  the  use  of  the  mallet,  which 
involves  the  use  of  the  left  hand  in  such  an  expert  manner  that  he  will, 
with  it,  perfectly  obtain  his  line  of  force  and  the  proper  amount  of 
hand-pressure. 

The  making  of  a  gold  filling  means  more  than  the  mere  adaptation 
of  the  gold  to  the  walls  of  the  cavity.  That  may  be  perfectly  accom- 
plished and  still  the  filling  may  be  a  failure.  If  the  gold  has  not  been 
condensed  to  a  degree  that  gives  it  a  specific  gravity  of  at  least  14  it 
will  contain  so  great  a  percentage  of  air  spaces  that  it  will  be  little 
more  than  a  sponge  and  will  not  make  an  impermeable  filling.  It 
requires  considerable  force  to  obtain  a  high  degree  of  specific  gravity 
in  malleted  gold  in  a  tooth.  The  specific  gravity  of  gold  is  about  19.3 
and  a  filling  with  a  specific  gravity  of  18  will  make  a  filling  that  is  about 
as  nearly  perfect  as  the  hand  of  man  can  make  it,  so  far  as  density  is 
concerned;  but  a  filling  with  a  specific  gravity  of  16  will  make  a  very 
good  filling  and  few  operators  attain  that.  The  reason  that  so  many 
gold  fillings  in  the  posterior  teeth  begin  to  pit  and  break  down  in  a  short 
time  is  because  of  the  low  density  of  the  filling,  caused  by  the  failure 
to  obtain  sufficient  mallet  force  in  making  the  filling.  Most  of  this  is 
caused  by  a  failure  to  use  the  proper  methods  of  condensation  or  by 
improper  use  of  those  at  hand.  The  reason  we  prefer  to  use  the  pellets 
that  we  make  ourselves  is  because  we  desire  to  know  just  the  amount 
of  gold  that  is  under  our  plugger  point  at  a  given  time,  for  we  know  the 
amount  of  force  that  a  given  quantity  of  gold  must  receive  in  order  to 
obtain  a  certain  density.  In  order  to  obtain  this  definite  density, 
definite  methods  should  be  used.  With  the  hand  mallet  used  with  a 
force  of  ten  pounds  to  the  blow,  augmented  with  a  five-pound  hand- 
pressure  on  a  plugger  point  that  has  a  diameter  of  0.5  mm.  x  0.75  mm., 
give  20  blows  of  the  mallet  to  a  sixty-fourth  pellet,  40  to  a  thirty- 
second,  80  to  a  sixteenth  and  160  to  an  eighth.  This  method  will  give 
the  student  and  operator  a  definite  method  of  obtaining  a  specific 


FILLING  TEETH   WITH  GOLD  227 

gravity  that  is  as  nearly  perfect  as  he  will  be  able  to  obtain.  There 
are  always  sources  of  error,  of  course.  The  thickness  of  the  cushion 
of  the  peridental  membrane  will  cause  quite  a  serious  error  in  density 
if  it  is  great.  For  this  reason  it  is  very  difficult  to  make  a  good  hard 
gold  filling  for  children.  The  force  of  the  condensing  blow  is  so  greatly 
dissipated  by  the  elastic  cushion  made  by  the  thick  peridental  mem- 
brane that  it  is  inadvisable  to  attempt  large  gold  restorations  for 
children. 

Another  source  of  error  is  the  shape  of  the  plugger.  A  long,  thin 
curved  shank  on  a  plugger  will  take  up  a  very  large  amount  of  the  con- 
densing force  of  the  blow  in  the  elastic  spring  of  the  curved  shank. 
The  plugger  should  be  as  nearly  straight  as  it  is  possible  to  have  it  and 
yet  not  have  the  point  out  of  the  range  of  vision.  The  shank  should 
not  be  long  but  as  short  as  may  be  conveniently  made.  The  pluggers 
adopted  by  Drs.  Woodbury  and  Crandall  are  as  nearly  perfect  as  it  is 
possible  to  obtain,  and  are  the  ones  advised  in  this  treatise.  The  size 
of  the  plugger  point  is  also  of  great  importance  for  the  amount  of  force 
delivered  at  the  plugger  point  is  directly  proportional  to  the  force  of  the 
blow  and  inversely  proportional  to  the  square  of  the  plugger  point.  It 
will  thus  be  seen  that  an  increase  in  the  size  of  the  plugger  point  rapidly 
decreases  the  condensing  power  of  the  mallet.  Use  as  small  a  point 
as  is  consistent  with  good  results.  Too  small  a  point  chops  the  gold 
instead  of  condensing  it  and  too  large  a  point  fails  in  power  of  condensa- 
tion.    The  ideal  point  is  one  that  is  about  0.5  mm.  x  0.75  mm. 

Cohesion  and  condensation  are  important,  but  unless  the  gold  is 
perfectly  adapted  to  the  walls  of  the  cavity  it  wdll  make  no  difference 
how  dense  or  compact  the  filling  may  be;  it  will  fail  because  it  will 
leak.  Perfect  adaptation  of  the  gold  to  the  walls  of  the  cavity  is  the 
first  desideratum.  The  other  things  must  follow  in  the  making  of  a 
perfect  filling. 

The  adaptation  of  the  gold  to  the  walls  of  the  cavity  is  obtained  by 
the  right  use  of  the  plugger  in  flowing  the  gold  toward  the  walls  of  the 
cavity.  The  first  piece  or  two  of  gold  having  been  started  in  the 
convenience  point  or  angle  the  other  pellets  follow  in  sequence,  and  as 
they  are  placed  the  condensing  force  should  be  applied,  beginnmg 
toward  the  center  of  the  cavity  and  stepping  the  plugger  in  an  orderly 
sequence  toward  the  wall  against  which  the  gold  is  to  be  condensed. 
Each  step  of  the  plugger  should  be  about  the  distance  of  75  per  cent,  of 
the  diameter  of  the  plugger  point  so  that  the  operator  is  shingling  the 
gold,  each  blow  partly  overlapping  the  preceding  one  until  the  wall  of  • 
the  cavity  is  reached,  and  then  the  plugger  should  be  lifted  up,  retraced 
toward  the  center  of  the  cavity  and  again  stepped  toward  the  wall.  In 
tjiis  way  the  gold  is  being  continually  forced  toward  the  wall  of  the 


228     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

cavity  and  the  last  blow  upon  the  gold  is  that  which  wedges  it  tightly 
against  the  wall  of  the  cavity.  If  the  plugger  started  back  from  the 
wall  toward  the  center  of  the  cavity  it  would  be  found  that  the  gold 
would  be  drawn  away  from  the  wall  and  a  leaky  place  would  be  the 
result.  In  this  way  pellet  should  be  added  to  pellet,  laminating  the 
gold  back  and  forth,  building  up  and  forward  until  we  come  to  the  step 
of  the  cavity  leading  toward  the  gingival  surface.  It  will  be  remem- 
bered that  three  cylinders  of  non-cohesive  gold  were  placed  in  the 
gingival  surface  and  then  no  more  attention  was  paid  to  them;  but  the 
building  of  the  cohesive  gold  in  the  distal  portion  of  the  occlusal  step 
was  commenced.  The  cohesive  foil  is  built  forward  over  the  non- 
cohesive  cylinders  in  the  gingival  seat,  effectually  locking  them  to 
place.  The  gold  is  built  up  to  occlusal  and  proximate  form,  correctly 
contoured  and  the  size  and  shape  of  the  tooth  restored  as  perfectly  as 
possible. 

When  inserting  the  non-cohesive  cylinders  it  must  always  be  remem- 
bered to  so  place  them,  in  any  form  of  cavity,  that  the  ends  will  be 
extending  out  of  the  cavity  and  not  the  sides.  This  rule  having  been 
adhered  to  in  this  case,  we  will  find  the  ends  of  the  cylinders  tightly 
resting  against  the  approximating  tooth.  With  a  long,  fairly  wide 
foot  plugger  the  cylinders  are  malleted  into  the  cavity  by  inserting  the 
foot  plugger  between  the  approximating  tooth  and  the  gold  and  making 
strong  condensation  with  the  hand  mallet.  This  drives  the  non- 
cohesive  cylinders  tightly  into  the  cavity  and  firmly  against  all  margins, 
and  maintains  a  perfect  adaptation  at  the  gingival. 

The  use  of  the  combination  of  non-cohesive  and  cohesive  gold  is 
only  possible  in  that  class  of  cavities  that  will  enable  the  cohesive  gold 
to  be  perfectly  anchored  in  the  tooth  without  the  aid  of  the  non-cohe- 
sive gold,  for  there  will  be  no  cohesion  between  the  two  kinds  of  gold. 
For  instance,  we  use  the  non-cohesive  foil  in  the  gingival  third  of 
bicuspids  and  molars  because  the  non-cohesive  cylinders  may  be  keyed 
into  the  cavity  by  condensing  the  cohesive  foil  over  them  and  anchoring 
the  cohesive  foil  in  the  step  in  the  occlusal  surface.  That  retention 
will  be  sufficient  to  retain  the  filling  without  the  aid  of  the  retention  in 
the  gingival  third.  Also,  in  the  occlusal  surfaces  of  the  molars,  when 
the  non-cohesive  foil  is  adapted  to  the  walls  of  the  cavity,  the  center 
may  be  wedged  with  the  cohesive  and  it  will  maintain  itself,  even 
though  there  is  no  cohesion  between  the  two  kinds  of  gold. 

In  the  case  of  a  proximate  cavity  in  an  incisor  it  will  be  necessary  to 
use  the  cohesive  foil  entirely,  because  the  cavity  will  need  all  of  the 
retention  of  the  cohesive  gold  to  maintain  the  filling.  This  is  also  true 
of  all  fourth-class  cavities,  for  in  these  there  will  not  be  sufficient 
incisal  anchorage  to  retain  the  filling  if  non-cohesive  foil  be  used  in 


FILLING  TEETH  WITH  GOLD 


229 


the  gingival  third.  The  rule  is  to  use  the  non-cohesive  foil  in  only 
those  cavities  in  which  sufficient  anchorage  may  be  obtained  for  the 
filling  after  the  non-cohesive  foil  is  in  place. 

Class  III  cavities  are  filled  with  cohesive  foil,  beginning  the  filling  by 
placing  a  pellet,  No.  32,  in  the  linguo-gingival  angle  and  slightly  con- 
densing it.     At  this  point  in  the  operation  an  assistant  plugger  is  invalu- 


FiG.   164. — Cavity  ready  for  filling. 


able.  This  may  simply  be  any  other  plugger  that  is  used  to  hold  the 
pellet  of  gold  steadily  in  place,  while  the  condensing  force  is  being 
applied,  or,  better  still,  it  may  be  in  the  form  of  a  gold  carrier  that  is 
used  to  pick  up  the  pellet  of  gold,  place  it  in  the  proper  position  and  then 
hold  it  steadily  during  condensation.  The  use  of  the  combined  carrier 
and  assistant  plugger  is  a  time-saver,  in  that  the  operation  of  picking  up 


Fig.  165. — Filling  started  in  linguo- 
gingival  angle  and  built  over  the  gingival 
waU  to  the  bucco-gingival  angle. 


Fig. 


166. — Same  process  carried 
farther. 


the  gold,  placing  it  in  the  cavity  and  holding  it  in  place  is  accomplished 
with  one  instrument  instead  of  two  if  pliers  were  used  to  carry  the  gold. 
A  very  useful  assistant  plugger  may  be  made  by  shaping  a  piece  of 
16-gauge  iridio-platinum  wire,  sharpening  it  to  a  point  and  using  it  in 
a  good-sized  broach  carrier.  The  iridio-platinum  will  have  the  advan- 
tage over  steel  in  that  it  will  not  contaminate  the  gold  with  any  dele- 


230    CAVITY  PREPARATION  AND  THE  FILLING  OF  TEETH 


terious  material.  Other  pellets  are  adapted  to  the  first  one,  building 
the  mass  of  gold  into  the  angle  and  gradually  condensing  the  gold 
across  the  gingival  wall  of  the  cavity.  In  placing  each  pellet  the 
condensing  force  should  be  begun  at  the  point  nearest  the  center  of  the 
cavity  and  stepping  the  plugger  toward  the  wall  against  which  the  gold 
is  being  condensed  at  that  particular  time.     Never  step  the  plugger 


Fig.  167. — Build  up  the  filling,  being 
careful  to  keep  the  lingual  portion  in 
advance. 


Fig.   168. — Mesial  angle  built  in. 


away  from  the  walls  toward  the  center.  The  last  blow  of  the  plugger 
should  be  at  the  extreme  point  of  adaptation  between  the  filling  and  the 
wall  of  the  cavity,  thus  calking  the  filling  by  wedging  the  gold  between 
that  already  condensed  and  the  wall  of  the  cavity.  The  assistant 
plugger  should  hold  the  gold  firmly  to  place  during  this  part  of  the 
condensation,  for  until  the  filling  is  built  across  the  gingival  seat  and 


Fig.   169. — Labial  wall  protected. 


Fig.   170.— Finished  filling. 


firmly  anchored  in  the  labio-gingival  angle,  locking  the  gold  in  the 
gingival  to  place  there  is  danger  of  displacing  the  filling  and  causing 
it  to  rock.  If  such  an  accident  does  occur,  immediately  remove  the 
gold  already  placed  and  begin  over,  for  it  will  be  almost  impossible 
to  make  an  impervious  filling  after  a  portion  has  loosened  from  its 
anchorage. 


FILLING  TEETH  WITH  GOLD  231 

When  the  filling  is  Ijuilt  up  along  the  gingival  wall  and  thoroughly 
locked  to  place  the  lingual  wall  of  the  cavity  should  be  built  up.  The 
lingual  wall  should  be  perfectly  protected  before  much  gold  is  added  to 
the  body  of  the  filling,  for  if  this  is  not  done  there  will  be  an  insufficient 
mass  of  gold  along  the  lingual  margin  and  it  will  be  very  difficult  to 
adapt  it  after  the  body  of  the  filling  is  built  up.  Access  to  it  from  the 
labial  aspect  will  have  been  destroyed  and  the  method  of  condensing 
from  the  lingual  surface  will  be  found  very  difficult,  if  the  filling  is 
started  from  the  labial.  After  the  lingual  wall  is  well  built  the  body  of 
the  filling  may  be  filled  in,  being  very  careful  not  to  trap  the  labial  wall 
of  the  cavity  without  a  sufficient  quantity  of  gold  to  fill  it,  for  there 
again  difficulty  will  be  met  in  adapting  the  gold  if  there  is  no  room  to 
do  so.  When  the  filling  approaches  the  cavo-surf  ace  angle  of  the  cavity 
the  gold  should  be  lapped  over  the  margin  with  a  burnishing  motion 
of  the  plugger.  No  condensing  force  should  be  applied  until  a  sufficient 
mass  of  gold  is  in  place  to  protect  the  enamel  margin  from  the  impact 
of  the  plugger.  If  this  were  not  done  and  the  sharp  serrations  of  the 
plugger  were  driven  through  the  thin  mass  of  gold  against  the  enamel 
margin  there  would  be  grave  danger  of  checking  the  enamel.  When 
the  first  pellet  is  burnished  over  the  margin,  condense  up  to  the  cavity 
wall  and  then  place  another  pellet  and  burnish  it  over  the  first,  repeating 
this  operation  several  times,  when  a  sufficient  mass  of  gold  will  protect 
the  margin  to  allow  condensation.  The  walls  of  the  cavity  having 
been  cared  for,  the  filling  should  be  contoured  to  form,  the  surface 
thoroughly  condensed  and  it  is  ready  for  the  finishing. 

The  pluggers  used  in  the  condensation  of  both  the  non-cohesive  and 
the  cohesive  foils  are  the  Woodbury-Crandall  set  of  26.  This  selection 
of  pluggers  is  most  admirable  and  the  student  will  find  all  of  the  points 
necessary  for  any  filling  that  he  will  be  called  upon  to  make.  We  can 
do  no  better  in  giving  a  description  of  the  pluggers  and  their  use  than 
to  use  the  words  of  the  designers:  Woodbury-Crandall  gold  pluggers 
are  designed  for  use  in  conjunction  with  a  hand  mallet  in  the  hands  of 
an  assistant.  The  forms  are  sufficient  for  any  gold-foil  operation, 
though  special  forms  may  be  added  as  conveniences  rather  than 
necessities. 

The  set  is  made  up  of  fourteen  pluggers  for  cohesive  gold  numbered 
from  1  C  to  14  C ;  nine  pluggers  for  non-cohesive  gold,  numbered  from 
15  NC  to  23  NC.  Nos.  1  C  and  2  C  are  for  general  work.  No.  1  C 
is  used  for  starting  fillings,  filling  very  small  cavities,  convenience 
points,  etc.;  No.  2  C  for  general  open  work  in  building  up  a  filling  after 
it  has  been  started. 

Nos.  3  C  and  4  C  are  for  building  along  parallel  walls,  driving  the  gold 
into  sharp  line  angles  and  for  general  building.    Their  convex  face 


232     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

causes  the  gold  to  spread  more  freely  than  a  flat  face  does,  thus  obtahi- 
mg  more  fully  the  effect  of  the  wedging  principle.     These  instruments 


vmmrmmmwimgi/, 


are  also  useful  when  approaching  a  margin,  as  their  round  face  is  not 
likely  to  chip  the  enamel  as  a  flat  face. 

Nos.  5  C  and  6  C  are  for  use  in  those  locations  that  are  not  conven 


so 


FILLING  TEETH   WITH  GOLD 


233 


iently  reached  by  Nos.  3  C  and  4  C;  their  bends  make  them  more 
convenient,  but  also  more  springy.  They  are  best  used  as  auxiliaries 
to  Nos.  3  C  and  4  C. 


'M&MiimkUi  Mil  i  li  MMi'MUlML 


No.  7  C  is  especially  designed  for  filling  the  retention  form  in  the 
incisal  angle  and  the  labio-gingival  angle  of  cavities  in  the  proximate 
surfaces  of  anterior  teeth. 

No.  8  C  is  convenient  for  use  in  the  distal  and  occlusal  surfaces  of 
bicuspids  and  molars. 


234     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

The  form  of  No.  9  C  allows  the  flat  end  of  the  plugger  to  bear  upon 
those  places  where  it  is  necessary  to  incline  the  plugger  to  quite  a  degree 
to  reach  different  parts  of  the  cavity. 


Fig.   172. — Fourth  class  cavity  ready  for  filling. 


Fig.   173. — Starting  in  gingival  angles  and 
building  across  gingival  walls. 


Fig.   174. — Continuing  the  building. 


Fig.   175. — Progress. 


Fig.   176. — Gold  built  up  to  incisal  step. 
Now  starting  in  pit  in  mesial  surface- 


No.  10  C  is  used  to  reach  inaccessible  places,  condense  over  angles, 
smooth  the  surface  of  the  gold,  etc. 
Nos.  lie  and  12  C  are  for  use  on  the  distal  and  occlusal  surfaces  of 


FILLING  TEETH   WITH  GOLD 


235 


bicuspids  and  molars,  the  long  angles  allowing  almost  any  part  of  these 
surfaces  to  be  reached  with  a  correct  line  of  force. 


Fig.   177. — Built  over  incisal  surface  and 
anchored  to  body  of  filling. 


Fig.   178.— Gold  all  built  in. 


Fig.   179.— Finished  filling. 


Fig.   180. — Class  V  cavity  ready  for 
filling. 


Fig.   181. — Gold  started  in  disto-gingival 
angles  and  built  up  to  disto-mesial  angle. 


Fig.   182.— Gold  built  over  floor  of 
cavity. 


Nos.  13  C  and  14  C  are  back-action  pluggers,  intended  for  use  only 
in  locations  that  cannot  be  reached  with  a  correct  line  of  force  with 
direct-action  pluggers.  These  two  instruments  have  twelve-inch 
handles,  with  hard-rubber  grips. 


236     CAVITY   PREPARATION  AND   THE  FILLING  OF  TEETH 

Nos.  15  NC  to  23  NC,  for  non-cohesive  gold,  should  never  be  used 
for  cohesive  gold,  as  they  have  faces  so  large  that  cohesive  gold  cannot 
be  condensed  with  them. 


Fig.   183. — Process  continued. 


Fig.  184. — Building  gold  over  cavo- 
surface  angle,  burnishing  it  over  to 
obtain  mass  before  malleting. 


Fig.   185. — ^All  cavo-surface  angles 
protected. 


Fig.   186.— Gold  all  built  in. 


Fig.   187.— Finished  filling. 

Nos.  15  NC  and  16  NC  are  used  to  drive  the  non-cohesive  cylinders 
against  the  gingival  wall  and  into  the  axio-gingival  line  angle  in  cavities 
in  the  proximo-occlusal  surfaces  of  bicuspids  and  molars. 

No.  17  NC  is  used  for  driving  the  cylinder  against  the  axial  walls 
in  cavities  in  occlusal  surfaces. 


FINISHING  THE  FILLING  237 

Nos.  18  NC  and  19NC  are  used  for  driving  the  cylinders  farther  into 
the  cavity  from  the  occlusal  surface  after  the  filling  has  otherwise 
been  made. 

Nos.  20  NC  and  21  NC  are  for  use  in  cavities  in  the  proximo-occlusal 
surfaces,  mesial  aspect,  for  driving  the  cylinders  in  the  interproximate 
space  against  the  axial  wall,  after  the  filling  has  been  otherwise  com- 
pleted. 

Nos.  22  NC  and  23  NC  are  back-action  pluggers  for  use  on  distal 
surfaces  in  the  same  way  that  20  NC  and  21  NC  are  used  on  mesial 
surfaces.     They  have  twelve-inch  handles  with  hard-rubber  grips. 

FINISHING  THE  FILLING. 

The  filling  should  be  finished  with  as  perfect  a  polish  as  that  which 
nature  gives  to  the  enamel  of  the  tooth  for  the  reason  that  food  debris 
will  not  cling  to  a  polished  surface  as  well  as  to  a  rough  or  uneven  one. 
All  margins  of  the  filling  should  be  flush  with  the  tooth  surface  so  that 
an  explorer  will  not  catch  between  the  tooth  and  filling  when  lightly 
passed  over  the  surface.  This  is  particularly  true  of  the  finish  at  the 
gingival  margin,  for  here  a  rough  or  overhanging  margin  will  be  the 
cause  of  a  considerable  irritation  to  the  gingival  tissue  with  a  resulting 
inflammation  and  a  not  infrequent  pyorrhea.  Many  teeth  have  been 
lost  by  the  careless  placing  of  a  filling  with  rough  overhanging  margins. 
Dr.  Arthur  Black  and  others  have  demonstrated  that  many  cases  of 
pyorrhea  have  had  their  inception  in  such  faulty  operations.  It  is 
therefore  essential  that  the  filling  should  be  finished  as  perfectly  as 
possible.  The  first  point  in  the  operation  of  finishing  the  filling  is 
trimming  to  form.  The  contour  of  the  tooth  and  the  true  anatomic 
form  of  the  occlusal  surface  should  be  accurately  reproduced.  In 
order  to  do  this,  the  student  must  possess  the  knowledge  of  tooth  form, 
for  without  an  accurate  conception  of  the  form  of  the  tooth,  he  will  not 
be  able  to  reproduce  it. 

In  finishing  fillings  placed  in  the  occlusal  surfaces  of  molars  and 
bicuspids,  the  filling  should  be  ground  down  to  approximate  occlusion 
with  a  suitable  carborundum  stone  of  the  proper  size.  It  should  not 
be  too  large  to  be  of  service  in  bringing  the  surface  of  the  filling  to  a 
relatively  close  approximation  of  the  form  desired,  nor  should  it  be  so 
small  that  it  will  be  likely  to  cut  the  surface  of  the  filling  and  make  it 
irregular.  After  the  stone  has  brought  about  an  approximation  of  the 
result  desired,  a  round  finishing  bur  is  used  to  carve  the  surface  of 
the  tooth  making  therewith  the  sulcus  and  grooves  thus  making  the 
surface  of  the  filling  correspond  with  the  surface  of  the  natural  tooth. 
The  skill  and  artistic  ability  of  the  operator  can  be  given  full  play  at 


238     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

this  point  and  results  beautiful,  as  well  as  useful,  will  follow  in  the 
train  of  a  well-executed  finish.  After  the  filling  is  trimmed  to  form  and 
occlusion,  as  well  as  to  anatomic  correspondence,  it  should  be  well 
polished.     This  can  be  accomplished  by  the  use  of  the  rubber  cups 


Fig.   188. — G.  V.  Black's  adjustable  saw  frame. 

charged  with  wet  pumice  and  rapidly  revolved  in  the  engine  hand  piece. 
If  a  high  polish  is  desired  the  wet  pumice  may  be  followed  by  dry 
pumice,  used  with  the  same  instrument  to  be  followed  by  any  of  the 
tooth  powders,  also  used  dry.     This  will  give  a  very  high  polish,  but  in 


Fig.   189. — G.  V.  Black's  finishing  files  and  knives. 

the  opinion  of  the  authors  is  contra-indicated  in  all  fillings  that  come 
within  the  range  of  vision  for  a  highly  polished  gold  filling  will  so  absorb 
the  rays  of  light  that  it  will  look  almost  black.  The  best  way  to  leave 
the  filling  is  with  the  w^ll  snioothed  surface  that  is  obtained  hy  the  use 


FINISHING  THE  FILLING  239 

of  the  wet  pumice,  or  a  very  fine  sandpaper  disk.  This  leaves  a  surface 
that  does  not  look  dark  but  on  reflection  of  light  shows  in  its  true 
color. 

In  finishing  a  filling  in  the  proximate  surface  of  a  molar  or  bicuspid 
the  approximate  form  is  reproduced  by  the  use  of  a  Black  saw,  knives 
and  files.  The  Black  saw  is  one  of  the  most  useful  instruments  ever 
devised  for  the  finishing  of  the  proximate  surface  of  gold  fillings.  It  is 
a  heavy  saw  frame  into  which  is  inserted  a  Kaeber  saw,  which  has  been 
ground  down  upon  its  smooth  edge  until  the  saw  is  of  thread  form. 
The  grinding  of  the  saw  is  accomplished  by  inserting  it  in  the  saw  frame 
and  holding  the  back  of  the  saw  against  a  carborundum  stone  in  the 
engine  or  lathe  until  the  desired  width  has  been  secured.  The  entire 
back  of  the  saw  is  ground  down  with  the  exception  of  the  portions  that 
engage  with  the  saw  frame,  for  if  these  were  ground  down  the  saw 
would  not  maintain  itself  in  the  frame  when  it  was  in  use;  therefore, 
the  ends  of  the  blade  should  be  left  as  they  come  from  the  manufac- 
turer. 

In  use  the  saw  blade  is  inserted  into  the  interproximate  space,  above 
the  filling,  with  the  teeth  toward  the  occlusal  surface.  If  there  is  not 
room  to  insert  the  saw,  space  can  be  made  by  cutting  out  a  portion  of 
the  gold  with  a  Black  knife.  These  knives  are  illustrated  in  the 
Woodbury-Crandall  set  as  Nos.  34  and  35.  The  saw  is  inserted  and 
the  frame  attached  to  it  as  it  is  in  its  position  between  the  teeth.  This 
is  necessary  for  the  reason  that  we  wish  to  cut  the  gold  out  of  the  inter- 
proximate space,  but  do  not  want  to  cut  away  any  of  the  contact. 
Therefore,  the  saw  must  be  inserted  above  the  filling  and  the  gold 
removed  from  the  interproximate  space  by  sawing  from  the  gingival 
margin  toward  the  occlusal  surface.  In  this  way  the  surplus  gold 
can  be  easily  and  most  expeditiously  removed  from  the  interproximate 
space  with  ease  to  the  operator  and  comfort  to  the  patient.  The  cutting 
with  the  saw  must  stop  short  of  the  contact,  for  to  cut  through  that 
would  be  to  ruin  the  form  of  the  filling.  When  the  gold  is  removed 
to  the  contact  point  the  saw  should  be  disengaged  from  the  frame  and 
drawn  out  of  the  interproximate  space  by  pulling  it  out  of  the  buccal 
embrasure.  The  contour  form  is  finished  by  the  use  of  the  Black  files, 
or  those  designed  by  Dr.  J.  M.  Prime.  With  these  files  the  form  of  the 
filling  may  be  made  to  conform  perfectly  to  the  shape  of  the  tooth, 
being  careful  to  make  all  the  lines  of  the  filling  slope  toward  the  contact 
point,  which  should  not  be  finished  until  the  last.  With  the  Black 
knives,  careful  search  should  be  made  for  any  overhang,  and  if  any 
is  discovered  it  should  be  removed  and  the  gingival  margin  made 
perfectly  flush  and  smooth.  The  occlusal  form  should  be  reproduced 
with  stones  and  burs  as  in  an  ordinary  occlusal  surface  filling,  being 


240     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

very  careful  to  see  that  the  marginal  ridge  is  maintained.  If  the 
marginal  ridge  is  not  reproduced  and  the  sulcus  made  so  that  the  bolus 
in  its  excursion  over  the  tooth  in  mastication  is  driven  toward  the 
middle  of  the  tooth  and  out  of  the  sides  of  the  embrasure  instead  of 
toward  the  contact,  there  will  be  a  very  great  probability  of  the  food 
finding  its  way  between  the  contacts  and  into  the  interproximate 
space,  to  the  great  detriment  of  the  septal  tissue  and  the  inconvenience 
and  pain  of  the  patient.  For  this  reason,  the  occlusal  surface  of  the 
tooth  should  never  be  ground  flat  as  has  been  the  custom  of  many 
good  operators  in  the  past.  Nature  made  the  form  of  the  tooth  not 
only  for  the  purpose  of  the  mastication  of  the  food,  but  also  so  shaped 
it  that  in  the  process  of  mastication  that  function  could  be  normally 
accomplished  without  harm  to  the  investing  tissues. 

If  the  separator  is  in  position  it  should  now  be  tightened  a  little,  in 
order  to  obtain  a  little  more  space  to  finish  the  contact  point.  If  it  is 
not  on,  it  should  be  placed  and  the  desired  space  obtained.  Very  little 
finishing  of  the  contact  point  is  needed,  for  if  the  work  thus  far  has  been 
properly  done  the  whole  of  the  filling  is  finished  to  form,  and  as  all  of 
the  lines  of  the  filling  slope  toward  the  contact,  that  point  will  be  but  a 
point  indeed,  and  all  that  will  be  required  to  finish  it  will  be  to  obtain 
the  requisite  space  and  pass  a  polishing  strip  between  the  points  and  a 
few  moments  of  the  same  will  finish  the  operation.  In  the  use  of 
sandpaper  disks  for  finishing  the  fillings  in  the  posterior  teeth  the  right 
angle  mandrel  is  indispensable,  for  the  proper  angle  of  approach  cannot 
be  obtained  by  the  use  of  the  straight  hand-piece.  In  the  use  of  the 
right  angle  the  operator  will  immediately  see  many  of  its  advantages 
and  will  soon  add  places  in  which  he  will  find  the  instrument  of  the 
greatest  assistance.  The  interproximate  portions  of  the  filling  may  be 
polished  with  a  fine  strip,  the  rest  of  the  filling  disked  and  the  whole 
polished  with  the  rubber  cup  and  wet  pumice.  When  the  separator 
has  been  removed  and  the  teeth  have  resumed  their  normal  relation 
the  contacts  should  be  so  tight  that  a  piece  of  floss  silk  will  pass  between 
them  with  a  decided  snap. 

Fillings  in  the  proximate  surface  of  incisors  are  finished  to  form  with 
files  and  knives,  the  gingival  space  polished  with  a  sandpaper  strip, 
and  the  labial  and  lingual  portions  disked  with  the  aid  of  the  right- 
angle  mandrel,  after  which  separation  should  be  made  and  the  contact 
polished  with  a  fine  strip. 

In  the  use  of  the  sandpaper  strip  it  should  be  cut  on  one  end  to  a 
narrow  point,  that  it  may  be  threaded  in  between  the  teeth  into  the 
interproximate  space.  Then,  in  the  posterior  teeth  especially,  it  is 
caught  in  the  end  of  a  split  instrument  that  engages  the  end  of  the  strip, 
which  when  wound  around  the  instrument  is  held  fast  and  the  operator 


AMALGAM  241 

using  the  instrument  in  the  mouth  to  hold  the  strip  and  managing  the 
other  end  with  his  hand  is  enabled  to  use  the  strip  with  more  ease  and 
certainty. 

The  instrument  may  be  made  by  taking  an  old  excavator  and  cutting 
a  slot  in  the  end  of  it  about  4  or  5  mm.  deep  and  wide  enough  to 
accommodate  a  strip  easily. 

At  no  place  in  performing  an  operation  does  the  finished  product 
display  the  skill  of  the  operator  so  much  as  in  the  form  and  finish  of 
the  filling.  It  therefore  behooves  every  dentist  to  survey  more  critically 
his  own  handiwork  in  the  light  of  the  finished  product,  and  strive  more 
earnestly  to  make  the  finish  of  a  gold  filling  perfect. 

AMALGAM. 

Amalgam  is  an  alloy  of  any  metal  with  mercury.  In  dentistry  it 
may  be  an  alloy  of  copper  and  mercury  making  the  copper  amalgam, 
or  it  may  be  an  alloy  of  two  or  more  metals  with  mercury,  as  in  the 
silver  tin  alloys,  which  are  in  general  use  by  the  profession  today. 
Copper  amalgam  has  many  points  of  superiority  in  that  it  will  neither 
shrink  nor  expand,  and,  by  reason  of  its  great  plasticity,  is  easily 
adapted  to  the  walls  of  a  cavity.  It  is  used  very  sparingly  in  dentistry 
today  because  of  the  fact  that  it  rapidly  wears  out  of  the  cavity  and  also 
because  of  its  black  color.  In  the  filling  of  deciduous  teeth,  however, 
it  has  a  place  that  is  entitled  to  respect,  for  here  it  usually  maintains 
its  integrity  as  long  as  it  is  wanted;  also  the  antiseptic  action  of  the 
copper  salts  makes  it  a  very  valuable  aid  in  saving  children's  teeth 
when  utility  for  a  short  space  of  time  is  paramount  to  appearance. 

The  silver  tin  alloys  are  the  ones  in  general  use,  and  the  reader  is 
referred  to  Chapter  VII  for  a  study  of  the  physical  characteristics, 
formulse  and  methods  of  manufacture.  This  article  will  attempt  to 
illustrate  only  the  technic  of  the  filling  of  teeth  with  amalgam,  leaving 
all  discussion  concerning  its  properties  to  the  author  of  the  chapter  on 
that  subject. 

The  preparation  of  the  cavity  for  the  reception  of  a  filling  of 
amalgam  is  identical  with  that  for  a  gold  filling,  except  that  the  cavo- 
surface  angle  is  made  wider  to  allow  a  greater  mass  of  amalgam  at 
the  edge  of  the  filling,  thus  giving  the  filling  greater  edge  strength.  The 
reader  is  therefore  referred  to  the  article  on  the  preparation  of  cavities 
for  gold  fillings  by  the  authors  of  this  treatise. 

By  reason  of  the  color  of  amalgam,  its  use  is  not  indicated  in  the  ante- 
rior teeth  and  should  be  used  rarely,  if  ever,  anterior  to  the  first  molar. 
If  the  filling  preserved  its  color  at  all  times  it  would  not  be  so  objec- 
tionable, but  old  amalgam  fillings  invariably  become  much  discolored, 
16 


242     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

making  their  use  anywhere  within  the  range  of  vision,  a  very  doubtful 
practice.  If  the  filling  is  well  made  and  there  is  no  infiltration  of  moisture 
between  the  filling  a,nd  dentin  there  will  be  no  discoloration  of  the  tooth, 
but  if  there  is  a  leakage,  no  matter  how  slight,  there  will  be  a  discolora- 
tion of  the  dentin,  owing  to  the  formation  of  sulphids,  and  the  penetra- 
tion of  the  dentin  by  the  resulting  sulphids.  This  coloration  may  vary 
from  a  slight  grayness  near  the  margin  of  the  filling  to  a  dense  blue- 
black  of  the  entire  tooth.  A  result  of  this  kind  is  indicative  of  faulty 
manipulation  of  the  amalgam  under  the  plugger,  hence  the  necessity 
for  a  care  ul  technic  in  condensing  the  filling. 

In  order  to  successfully  fill  a  cavity  with  amalgam  it  is  necessary  to 
have  four  walls,  for  it  cannot  be  perfectly  condensed  unless  confined 
to  the  cavity  while  pressure  is  being  made.  All  simple  occlusal  cavities 
have  four  walls  and  can  therefore  be  filled  without  any  complications, 
but  cavities  in  the  proximate  surfaces  of  molars  and  bicuspids  should 


Fig.   190. — Copper  matrix  and  cavity. 

be  supplied  with  the  lost  wall.  This  is  accomplished  by  the  use  of  a 
matrix  of  some  sort.  The  matrix  that  is  made  for  the  particular  case 
under  consideration  is  advised. 

Such  a  matrix  is  made  by  taking  a  piece  of  thin  sheet  copper,  of  36 
gauge,  and  cutting  an  oblong  piece  that  will  conform  to  the  length  of 
the  tooth  and  be  long  enough  to  encircle  the  tooth  to  about  two-thirds 
of  its  diameter.  A  small  wing  is  turned  up  at  each  of  the  corners  that 
are  to  be  at  the  gingival  portion  of  the  tooth  to  be  the  recipient  of  the 
matrix,  for  the  purpose  of  holding  the  ligature  and  preventing  it  from 
slipping  off  the  matrix  into  the  gum.  The  matrix  is  now  adapted  to 
the  tooth  and  a  piece  of  floss  silk  thrown  around  it,  making  a  double 
turn  of  the  silk.  This  is  drawn  tight,  carefully  watching  to  see  that  the 
matrix  is  being  properly  adapted  to  the  tooth.  Too  much  stress  should 
not  be  applied  to  the  silk  or  it  will  cause  the  matrix  to  be  pushed  into 
the  cavity  on  the  proximate  aspect  of  the  tooth.     After  the  matrix  is 


AMALGAM  243 

ascertained  to  be  in  proper  relation  to  the  tooth  and  cavity,  and  it  is 
seen  that  it  properly  restores  the  lost  wall  of  the  tooth,  the  ligature 
should  be  tied  and  the  matrix  held  perfectly  in  place.  If  the  matrix 
does  not  fit  at  the  gingival  margin  it  is  advisable  sometimes  to  adapt 
a  small  orange-wood  wedge  at  the  gingival  margin  to  hold  the  matrix 


Fig.   191. — Matrix  tied  on. 

firmly  to  place  and  prevent  the  amalgam  being  forced  between  the  matrix 
and  the  tooth  into  the  gum.  If  this  happens,  and  it  is  not  discovered 
and  removed,  it  will  cause  a  very  sore  tooth  and  the  possible  loss  of  the 
same  by  the  severe  inflammation  which  such  an  irritant  may  cause. 
The  matrix  should  now  be  contoured  from  within  the  cavity  with  a 
small  ball  burnisher  and  the  contact  made  by  cutting  a  hole  in  the  cop- 
per matrix  with  a  No.  4  round  bur.     This  will  leave  a  hole  at  the  con- 


Matrix  wedged  at  gingival. 


tact  point  which  will  enable  the  operator  to  condense  the  amalgam  at 
that  point  directly  against  the  approximating  tooth,  preventing  the 
displacement  of  the  amalgam  and  making  it  possible  to  obtain  a  very 
tight  contact.  The  cavity  should  be  prepared,  dam  in  place,  matrix 
adapted  and  all  things  in  readiness  before  the  amalgam  is  mixed. 


244     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

When  making  an  amalgam  filling  the  point  of  greatest  interest  is  the 
choice  of  the  alloy,  for  failure  to  use  a  good  alloy  will  cause  a  failure  of 
the  filling.  The  operator  may  do  some  things  perfectly,  but  no  man 
can  operate  a  faulty  alloy  in  such  a  way  that  he  can  make  a  filling  that 
will  stand  the  stress  of  time  and  mastication.  At  the  present  time, 
happily,  there  is  little  need  of  making  a  faulty  selection.  Expansion 
and  shrinkage  of  the  filling  is  out  of  the  hands  of  the  operator  and  in 
the  hands  of  the  manufacturer,  but  the  strength  or  weakness  of  the 
filling  is  largely  an  operative  procedure.  Too  much  mercury  in  the 
mix,  so  that  a  sloppy  mass  is  the  result,  will  make  a  weak  filling,  while 
too  little  mercury  will  also  make  a  weak  filling  and  one  that  has  a 
tendency  to  be  very  brittle.  Therefore,  to  make  a  strong  filling  it  will 
be  safer  to  have  the  proper  amounts  of  alloy  and  mercury  at  each  mix. 
This  is  accomplished  by  weighing  the  separate  parts  of  the  mix  on  a 
balance,  first  ascertaining  the  proportion  of  alloy  and  mercury  to  take 
for  the  particular  alloy  that  is  to  be  used.  This  can  be  done  by 
experiment,  finding  the  amount  of  mercury  that  will  give  the  proper 
consistency  to  a  definite  amount  of  alloy.  The  amalgam  that  gives  the 
best  results  is  a  mix  that,  when  well  kneaded,  will  leave  the  print  of 
the  fingers  well  outlined  on  the  mass.  When  the  proper  amounts  to 
produce  this  consistency  have  been  obtained  it  is  advisable  to  weigh 
out  a  number  of  such  units  of  alloy  and  place  them  in  ordinary  gelatin 
capsules  and  set  them  aside  until  wanted.  The  same  may  be  done 
with  the  mercury.  The  proper  amount  of  mercury  is  weighed  and 
placed  in  capsules;  when  a  filling  is  to  be  made  a  capsule  of  alloy  and 
one  of  mercury  are  taken  and  the  mix  made  from  them.  If  the  proper 
amounts  have  been  ascertained  and  carefully  weighed  out  there  will 
be  approximately  the  right  mixes  every  time  without  the  care  and 
thought  whenever  a  filling  is  to  be  made. 

The  alloy  and  mercury  are  placed  in  a  good-sized  Wedgewood  mortar 
and  thoroughly  triturated  until  a  good  amalgamation  has  been  secured, 
when  the  mass  is  turned  into  the  hand  and  kneaded  thoroughly  for  some 
time  until  a  perfectly  homogeneous  mix  is  obtained,  which,  as  has  been 
said,  is  evidenced  by  the  fact  that  the  resultant  mass  will  reproduce 
the  marks  of  the  fingers  upon  its  surface.  There  is  one  school  of 
amalgam  operators  that  teaches  that  the  filling  should  be  made  from  a 
mix  that  is  so  soft  that  it  is  sloppy  in  order  to  obtain  a  more  perfect 
adaptation,  while  another  school  insists  upon  the  use  of  a  mix  that  is  so 
stiff  that  it  is  almost  impossible  to  get  it  into  the  cavity  before  it  has 
set.  Neither  school  is  correct,  for  the  sloppy  mix,  while  seemingly 
easier  to  adapt  to  the  walls  of  the  cavity,  in  reality  is  not  so,  and  the 
fact  that  such  a  mix  is  bound  to  make  a  filling  that  will  be  too  weak 
to  stand  the  stress  of  continued  use  would  be  enough  to  discredit  it. 


AMALGAM 


245 


The  too  stiff  mix  is  so  difficult  to  manipulate  that  the  majority  of  fillings 
made  with  it  will  be  found  of  faulty  adaptation.  The  better  way  is  to 
choose  the  medium  mix  which  will  make  possible  a  good  adaptation 
and  a  strong  permanent  filling,  if  properly  condensed.  This  mass 
should  be  broken  into  several  fragments  and  is  ready  for  the  filling.^ 

The  instruments  that  are  used  in  condensing  the  amalgam  are  those 
selected  by  Dr.  Crandall.  We  reproduce  the  illustrations  and  explana- 
tion of  their  use  by  their  designer: 


15 

40 

50 

60 

SO 

30 

18 

35 

50 

so 

8 

10 

10 

12 

12 

0 

0 

0 

0 

0 

10 

11 

12 

13 

14 

3 

6 

20 

20 

15 

16 

Fig.    193. — Walter  G.  Crandall's'amalgam'condensers. 


These  instruments  have  been  designed  to  fit  into  the  proximate  and 
occlusal  portions  of  such  cavities  as  are  usually  made  in  bicuspids  and 
molars  for  amalgam  fillings.  They  have  shortened  shanks,  bringing 
the  working  point  of  the  instrument  closer  to  the  grasp  that  controls 


1  The  reader  is  referred  to  the  section  on  Amalgam,  in  Chapter  VIII,  for  a  further 
discussion  of  this  subject. 


246     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

it  and  affording  great  leverage  and  very  accurate  control.  When  used 
as  pluggers  to  carry  a  mass  of  amalgam  and  to  condense  it  under  heavy 
hand  pressure  supplemented  by  mallet  force,  they  will  produce  the 
greatest  possible  density  and  strength  in  the  completed  restoration. 

Nos.  1  to  7  are  for  cavities  in  the  lower  teeth  which  are  inaccessible 
with  the  bayonet-shaped  instruments,  Nos.  8  to  14. 

Nos.  7  and  14  are  especially  valuable,  as  their  size  allows  them  to 
condense  a  mass  of  amalgam  over  all  of  the  margins  of  the  cavity 
simultaneously,  thus  avoiding  the  movement  away  from  some  portion 
of  the  margins  which  is  always  produced  by  the  use  of  small  pluggers. 

Nos.  15  and  16  are  amalgam  formers,  used  for  reducing  the  excess  of 
amalgam  to  the  cavity  margins  and  for  preliminary  carving  in  the 
restoration  of  the  natural  tooth  form. 

A  piece  of  amalgam  about  the  diameter  of  the  cavity  is  taken  in  the 
pliers  and  carried  to  the  cavity,  where  it  is  pressed  into  place  with  the 
finger,  and  pressed  firmly  to  the  floor  of  the  cavity  by  a  plugger  as  large 
as  the  entrance  will  permit.  Then  a  slightly  smaller  plugger  is  used  to 
condense  the  amalgam  against  the  walls,  carrying  the  material  from 
-the  center  of  the  cavity  toward  the  walls  thereof,  as  is  done  in  condens- 
ing a  gold  filling;  then  wedge  the  next  piece  in  between  the  amalgam 
condensed  against  the  walls,  thus  taking  advantage  of  the  wedging 
principle  in  forcing  the  material  more  tightly  in  its  adaptation  to  the 
walls  of  the  cavity.  This  should  be  continued  until  the  cavity  is  full, 
when  a  piece  of  amalgam  slightly  larger  than  the  orifice  is  placed  on 
the  filling  and  heavy  pressure  made  with  a  large  plugger,  which  may 
in  some  cases  be  advantageously  augmented  by  the  mallet.  The 
filling  is  made  more  dense  and  strong  in  proportion  to  the  pressure 
made  upon  the  amalgam  during  the  packing  of  the  filling.  Dr.  South- 
well, many  years  ago,  demonstrated  the  fact  that  very  few  amalgam 
fillings  were  able  to  withstand  a  pound  of  air-pressure  without  leaking, 
because  their  adaptation  to  the  walls  of  the  cavity  was  so  poor,  and 
Dr.  Crandall  admits  that  the  packing  of  an  amalgam  filling  in  order 
to  make  it  impervious  to  moisture  is  a  very  difficult  operation.  It 
therefore  behooves  the  student  to  study  the  technic  of  the  packing  and 
condensation  of  amalgam  with  the  greatest  care  if  he  expects  to  make  a 
success  of  its  manipulation. 

The  amalgam  should  be  allowed  to  set  for  several  minutes  until  it 
has  become  fairly  hard  before  the  matrix  is  removed,  and  then  care 
-must  be  exercised  not  to  break  the  filling  in  removing  it.  If  a  hole  has 
been  made  in  the  copper  at  the  point  of  contact,  and  the  portion  of  the 
matrix  extending  gingivally  above  the  surface  of  the  filling  has  been  cut 
.  before  the  matrix  is  applied,  the  matrix  can  usually  be  torn  asunder 
after  the  amalgam  has  hardened,  parting  at  the  point  where  the  hole 


AMALGAM  247 

was  made  for  the  contact,  when  the  two  ends  can  be  withdrawn  easily 
from  the  buccal  and  lingual  surfaces  and  the  filling  left  undisturbed. 
If  there  is  any  danger  of  breaking  the  filling  it  is  better  to  allow  it  to 
set  until  it  has  become  perfectly  hard,  when  it  may  be  manipulated 
as  desired. 

The  reason  that  it  is  desirable  to  remove  the  matrix  before  the 
amalgam  has  become  perfectly  hard  is  that  it  may  be  carved  to  form 
much  more  easily  before  it  attains  its  hardness. 

After  the  removal  of  the  matrix  the  filling  should  be  carved  to  con- 
tour with  the  Black  knives  and  polished  with  a  fine  sand-paper  strip, 
inserting  the  strip  between  the  teeth  gingivally  to  the  contact  point. 
This  can  be  done  more  expeditiously  if  the  strip  is  cut  to  a  point  and 
then  threaded  into  the  interproximate  space,  as  advised  in  the  finishing 
of  a  gold  filling. 

The  occlusal  surface  of  the  filling  should  be  made  to  resemble  the 
natural  tooth  as  closely  as  possible,  and  in  this  work  the  art  of  the 
operator  can  be  beautifully  demonstrated  in  the  carving  of  the  cusps 
and  sulci.  The  carving  of  an  amalgam  filling  is  so  easly  done  thatjthe 
making  of  a  flat  occlusal  surf  ace  on  an  amalgam  filling  is  little  short  of 
malpractice.     It  is  certainly  indicative  of  gross  carelessness. 

When  the  filling  is  carved  to  form  it  is  advisable  to  dismiss  the  patient 
and  polish  at  a  future  sitting,  when  the  filling  should  be  disked  to 
smoothness  and  polished  to  a  mirror  surface  by  the  use  of  rubber  cups 
and  pumice,  first  used  wet  and  then  dry  for  the  final  polish.  An 
amalgam  filling  so  made  will  give  the  patient  years  of  useful  service 
and  will,  in  a  high  degree,  resist  the  deposits  of  food  debris  upon  its 
surface  due  to  the  high  polish  which  it  will  take  and  retain. 

In  many  badly  broken-down  teeth  that  would  usually  require  crowns 
the  amalgam  filling  can  be  used  to  restore  the  tooth  to  usefulness  better 
than  a  crown.  In  these  cases  the  cavity  is  prepared  with  all  the 
retention  that  is  possible,  cutting  down  the  cusps  and  reinforcing  them 
by  carrying  the  metal  over  their  surfaces  and  restoring  them  with  the 
amalgam.  Frequently  in  those  cases  where  the  pulp  has  been  involved 
and  the  canals  filled  the  pulp  chamber  can  be  utilized  for  retention  and 
the  foundation  of  the  filling  made  in  it.  When  the  cavity  is  prepared 
a  copper  band  is  made  to  fit  the  case  or  a  ready-made  band  is  chosen 
and  adapted  to  the  tooth,  carefully  festooning  the  metal  where  it  would 
otherwise  impinge  upon  the  gum.  The  band  is  contoured  as  well  as  the 
skill  of  the  operator  will  permit,  which  can  be  done  more  easily  if 
the  band  is  slit  gingivally  from  the  contact,  thus  enabling  the  ligature 
to  adapt  it  more  closely  to  the  tooth.  The  band  will  be  allowed  to 
remain  upon  the  tooth  for  a  day  after  the  filling  has  been  made. 

The  contact  points  should  be  made  possible  by  cutting  a  hole  in  the 


248     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

band  at  the  proper  point  with  a  round  bur  and  the  cavity  is  ready  for 
the  fining.  Sometimes  it  is  difficult  to  adjust  the  dam  before  the  band 
has  been  placed.  If  so  it  will  be  an  easy  matter  to  place  it  after  the 
band  is  on  the  tooth,  for  it  will  take  the  form  of  the  tooth  and  the 
rubber  can  be  slipped  over  it. 


Fig.  194. — Copper  tube  festooned,  trimmed  and  prepared  for  mesio-occluso-distal 

cavity. 

The  amalgam  can  now  be  packed  into  the  band  using  all  the  care  that 
we  would  use  in  the  packing  of  an  ordinary  filling.  The  occlusal  sur- 
face should  be  carved  to  form  while  the  amalgam  is  still  plastic,  but  the 
remainder  of  the  finishing  would  better  be  left  until  the  following  day. 
The  band  should  be  left  in  place  until  that  time,  for  the  attempt  to 


Fig.    195. — Matrix  adjusted  and  tied. 

remove  it  would  be  likely  to  break  the  filling  and  spoil  the  entire  opera- 
tion. When  the  case  is  seen  the  next  day  the  band  should  be  split 
with  a  sharp  knife  and  removed  and  the  filling  dressed  to  shape 
with  stones,  disks  and  strips  and  polished  to  a  mirror  surface.  This 
operation  when  completed  will  be  of  better  service  than  that  given 


GUTTA-PERCHA  AND   THE  CEMENTS  249 

by  a  crown,  for  the  gingival  margin  is  smoother  and  less  liable  to  irrita- 
tion. In  all  operations,  whether  with  amalgam  or  any  other  material, 
one  of  the  objects  of  the  greatest  importance  is  to  obtain  a  smooth  and 
polished  surface  at  the  gingival  margin,  for  the  delicate  septal  tissue 
will  not  tolerate  the  slightest  roughness.  The  beginnings  of  pyorrhea, 
as  Drs.  G.  V.  and  Arthur  Black  and  others  have  pointed  out,  lie  in  the 
rough  gingival  margins,  due  either  to  faulty  dental  operations  or  to 
the  deposition  of  calcareous  substances  thereupon.  If  the  cause  is  a 
faulty  dental  operation  it  is  a  stigma  upon  the  operator  and  one  that 
the  student  should  teach  himself  to  abhor. 

In  summing  up,  making  an  acceptable  amalgam  filling  consists  of 
a  proper  cavity  preparation,  choice  of  a  good  alloy,  the  proper  manipu- 
lation of  the  alloy  and  mercury,  adaptation  of  a  well-made  matrix,  the 
condensation  of  the  filling,  the  removal  of  the  matrix  and  shaping  of 
the  filling  and  the  polishing  of  the  filhng. 

GUTTA-PERCHA  AND  THE  CEMENTS. 

Gutta-percha  is  a  very  valuable  temporary  filling,  but  is  not  used 
with  any  idea  of  permanency.  It  is  used  principally  as  a  sealing  for 
the  various  medicaments  used  in  the  treatment  of  teeth  and  as  a  stop- 
ping in  cavities  after  the  wax  pattern  is  made  for  an  inlay,  and  the 
patient  has  been  dismissed  for  a  future  sitting.  It  is  also  very  useful 
in  making  separations  where  the  teeth  have  fallen  together  by  reason 
of  extensive  decay,  and  it  is  necessary  to  separate  them  for  a  time  in 
order  to  produce  sufficient  space  to  restore  properly  the  mesio-distal 
diameter  of  the  tooth.  It  may  also  be  used  as  a  temporary  filling  in 
any  case  that  may  be  desirable,  but  not  with  any  thought  of  per- 
manency. 

The  cavity  preparation  for  gutta-percha  is  the  same  as  for  any  of  the 
plastics;  therefore  it  will  not  be  necessary  to  go  into  that  subject  in 
this  treatise. 

In  filling  the  cavity  with  gutta-percha  it  is  necessary  to  have  the 
cavity  dry,  for  the  material  will  not  adhere  to  a  wet  surface.  It  is  well 
to  moisten  the  cavity  with  the  oil  of  eucal}T)tus  or  oil  of  cajuput  prior 
to  the  introduction  of  the  filling,  for  these  oils  have  the  power  of  dis- 
solving gutta-percha  and  making  it  adhere  to  the  surface  of  the  tooth. 
The  gutta-percha  should  never  be  softened  in  the  flame,  for  to  do  so 
will  endanger  its  structure  by  overheating  and  consequent  disintegra- 
tion. If  too  high  a  degree  of  heat  is  used  it  will  catch  fire  and  burn. 
The  best  way  to  soften  it  is  to  place  small  pieces  of  the  material  on  a 
heating  tray  for  gold,  such  as  the  mica  that  is  used  over  an  alcohol 
lamp  to  heat  gold  or  if  the  Custer  gold  annealer  is  at  hand  it  may  be 


250     CAVITY  PREPARATION  AND   THE   FILLING  OF  TEETH 


used  conveniently  by  placing  a  piece  of  porcelain  or  glass  upon  it  and 
allowing  the  electricity  to  heat  the  porcelain  to  a  moderate  degree,  when 


1  [ 

': 

•  7  " " 

:,        J 

n   .^        njU 

uin"                               f 

i   >     U; 

SI  1 

"..                              S 

|"'iji 

|.,:" 

'■?             a 

f'Sl'S 

£S  nn 

J»"                    ! 

Hi 

ii 

1    1 

f.-sisg 

a,":" 

IS             : 

Fig.  196. — Rivet  plastic  instruments. 


GUTTA-PERCHA  AND   THE  CEMENTS  251 

the  heat  is  turned  off  and  the  gutta-percha  placed  on  the  porcelain. 
It  will  remain  warm  sufficiently  long  to  make  the  filling,  keeping  the 
gutta-percha  plastic,  the  very  best  possible  condition  for  use. 

A  suitable  set  of  instruments  for  the  introduction  of  the  gutta-percha 
and  cements  is  one  here  illustrated.  The  set  should  consist  of  smooth 
end  pluggers  of  slightly  curved  and  bent  angle  shape  in  order  to  make 
convenient  the  placing  of  the  material  in  any  cavity  no  matter  where 
situated;  also,  an  assortment  of  smooth  blades  of  slightly  curved  form 
for  the  trimming  of  the  material  in  the  proximate  surfaces. 

Gutta-percha  should  be  inserted  in  the  cavity  in  small  pieces  and 
adapted  to  the  walls  in  the  same  way  as  an  amalgam  filling,  that  is,  the 
material  should  be  forced  from  the  center  of  the  cavity  toward  the 
walls  thereof  and  the  following  pieces  inserted  in  the  space  in  the  center 
made  by  condensing  the  material  toward  the  walls  of  the  cavity,  this 
procedure  to  be  followed  until  the  cavity  is  full.  The  filling  may  be 
trimmed  to  form  with  the  warm  instrument,  for  to  attempt  to  cut  the 
gutta-percha  with  a  cold  instrument  will  pull  the  material  away  from 
the  walls  of  the  cavity  and  make  a  very  ragged  surface.  After  the 
filling  is  trimmed  to  form  it  may  be  further  smoothed  by  taking  a  firm 
piece  of  cotton  pellet  and  washing  the  surface  of  the  gutta-percha  with 
eucal3q3tus  or  cajuput. 

In  placing  gutta-percha  over  dressings  in  the  tooth  it  is  necessary  to 
use  a  great  deal  of  care  not  to  make  pressure  upon  the  medicament 
that  is  used,  for  if  over  a  pulp,  pressure  will  cause  a  great  deal  of  pain, 
and  if  over  a  dressing  placed  in  the  pulp  cavity  in  the  treatment  of 
root  canals  the  pressure  may  cause  a  portion  of  the  medicine  to  be  forced 
through  the  apical  foramen,  causing  intense  irritation  and  pain.  This 
may  be  obviated  by  the  careful  manipulation  of  the  material.  x\ 
small  piece  should  first  be  used  and  placed  over  the  medicine  saturated 
cotton  and  lightly  packed  to  place  with  a  warm  instrument  that  has 
been  moistened  with  eucalyptus.  After  this  piece  has  been  allowed  to 
harden  more  of  the  material  may  be  introduced,  but  care  should  be  used 
all  through  the  operation  not  to  use  too  much  pressure. 

Gutta-percha  is  invaluable  for  making  a  temporary  filling  in  a  cavity 
that  has  been  prepared  for  an  inlay  until  a  convenient  time  may  be 
obtained  for  the  setting  of  the  same.  In  such  cases  the  filling  should 
be  made  with  as  much  care  as  if  it  were  to  endure  for  a  longer  period 
for  if  the  gutta-percha  is  carelessly  jammed  into  the  tooth  and  up  into 
the  interproximate  space  it  will  crowd  out  the  septal  tissue  and  may 
cause  considerable  pain  as  w^ell  as  a  great  deal  of  damage. 

Gutta-percha  is  of  great  value  in  those  cases  in  which  the  gum  tissue 
has  crowded  into  a  cavity  in  a  tooth  that  has  had  the  decay  progress 
below  the  gum  and  has  caused  such  a  gingival  irritation  that  the 


252     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

gum  has  hypertrophied  to  such  an  extent  that  it  partly  or  entirely 
fills  the  cavity.  In  many  cases  it  is  possible  to  cut  out  the  tissue; 
but  some  cases  do  not  call  for  that  treatment,  when  a  gutta-percha 
plug  may  be  inserted  and  the  patient  instructed  to  call  again  the 
next  day.  If  the  tissue  has  been  displaced  to  the  extent  desired  a 
temporary  filling  of  the  gutta-percha  may  be  inserted,  care  being  used 
not  to  impinge  upon  the  septal  tissue  and  the  patient  dismissed  until  a 
time  desirable  for  finishing  the  operation.  If  the  tissue  is  not  suffi- 
ciently displaced  crowd  in  a  little  more  gutta-percha  until  the  gum  is 
entirely  clear  of  the  cavity  and  then  it  may  be  filled  as  usual. 

In  the  separation  of  teeth  which  have  fallen  together  by  reason  of 
decay  the  material  may  be  crowded  into  the  cavity  between  the  teeth, 
leaving  it  a  little  overfull,  so  that  the  patient  will  bite  upon  the  filling. 
In  doing  this  a  constant  pressure  will  be  made  against  the  two  teeth  and 
will  crowd  them  apart.  This  plug  may  be  worn  for  a  few  days  and  then 
replaced  with  a  new  one  that  is  again  a  little  more  than  full ;  this  treat- 
ment should  be  repeated  until  the  proper  amount  of  space  has  been 
obtained. 

CEMENTS. 

The  cements  used  in  dentistry  are  the  oxyphosphates  of  zinc  and 
copper  and  the  silicates.  The  student  is  referred  to  Chapter  VII  for 
a  description  of  the  chemical  and  physical  characteristics.  The  present 
article  will  only  comprehend  the  use  of  cements  in  dentistry. 

Practically  the  only  use  of  cements  for  the  filling  of  teeth  is  of  a 
temporary  nature,  for  the  permanent  cement  is  still  to  be  found. 
The  silicates  are  more  nearly  permanent,  but  the  silicate  that  will 
stand  the  test  of  permanency  is  yet  to  be  brought  to  the  attention  of 
the  profession.  It  is  a  great  mistake  that  will  undoubtedly  refiect 
upon  the  reputation  of  the  practitioner  to  tell  a  patient  that  any 
cement  is  permanent. 

It  may  be  good  practice  to  use  the  silicates,  for  their  esthetic  effect 
is  good  and  many  patients  prefer  it  to  the  unsightly  effect  of  gold;  but 
it  is  always  advisable  to  warn  the  patient  that  the  filling  may  have  to 
be  remade  from  time  to  time,  depending  upon  the  condition  of  the 
fluids  of  the  mouth  of  the  patient  under  consideration.  If  the  patient, 
with  this  understanding,  chooses  to  have  the  silicate  used,  well  and  good, 
but  a  patient  should  never  be  told  that  any  cement  filling  is  as  nearly 
permanent  as  some  other  materials. 

The  preparation  of  the  cavity  for  a  cement  filling  is  the  same  as  for 
any  other  filling  except  that  the  cavo-surf ace  angle  demands  a  different 
treatment,  owing  to  the  slight  edge  strength  possessed  by  the  cements. 


CEMENTS  253 

The  cavo-surface  angle  should  be  without  bevel  and  should  always 
follow  the  long  axis  of  the  enamel  rods,  so  that  there  will  be  no  short 
rods  upon  the  surface  of  the  cavity,  and  there  will  be  no  sharp  angle 
to  make  a  thin  portion  of  cement  at  the  edge  of  the  filling,  for  to  do  so 
will  be  to  cause  the  edge  to  break  away  and  leave  a  vulnerable  point 
for  the  beginning  of  a  recurrent  decay. 

For  a  filling  of  any  kind,  the  silicates  are  usually  to  be  preferred,  as 
they  are  less  soluble,  are  harder,  decidedly  more  harmonious  in  color 
and  will  make  a  more  lasting  filling  than  one  made  of  any  of  the 
zinc  cements;  therefore,  in  the  description  of  the  filling  of  teeth  with 
cement  the  silicates  are  understood. 

The  filling  must  be  made  under  the  most  exacting  conditions  of 
dryness,  for  the  slightest  amount  of  moisture  before  the  cement  has  set 
is  inimical  to  good  work  and  the  lading  quality  of  the  material.  The 
rubber  dam  should  therefore  always  be  placed  upon  the  tooth  before 
the  operation  and  the  cavity  dried  thoroughly.  It  is  nearly  always 
advisable  to  use  a  matrix  of  some  kind.  A  matrix  made  of  celluloid  is 
preferred,  as  it  imparts  a  smooth,  polished  surface  to  the  filling  and 
does  not  endanger  the  color  by  imparting  any  deleterious  product  to 
the  cement  during  its  manipulation  as  a  metal  matrix  might.  The 
slightest  foreign  substance  incorporated  with  the  cement  will  endanger 
its  integrity  and  will  be  likely  to  cause  a  discoloration  of  the  filling. 

If  the  filling  is  to  be  made  in  the  proximate  surface  of  an  incisor  a 
strip  of  thin  celluloid  is  inserted  between  the  surfaces  of  the  teeth  on 
the  side  opposite  the  one  that  is  to  be  filled,  and  then  one  end  brought 
around  the  lingual  surface  of  the  tooth  and  carried  over  the  cavity. 
To  illustrate:  if  a  cavity  presents  in  the  distal  surface  of  an  upper  left 
central  incisor  one  end  of  the  celluloid  strip  should  be  inserted  between 
the  two  central  incisors  and  the  other  end  carried  over  the  lingual  sur- 
face of  the  left  central  up  between  the  central  and  lateral,  thus  making 
the  strip  act  as  a  matrix  for  the  cavity  in  the  distal  surface  of  the  left 
central.  The  matrix  can  be  manipulated  with  the  fingers  to  suit  the 
operator  and  form  the  cement  under  the  celluloid  matrix. 

If  the  filling  is  to  be  in  a  proximate  surface  of  any  of  the  posterior 
teeth  the  celluloid  can  be  used  just  as  with  the  copper  matrix  for  an 
amalgam  filling,  only  using  the  celluloid  instead  of  the  copper. 

The  cement  should  be  mixed  upon  a  slab  made  by  using  the  surface 
of  a  large  flat  bottle.  This  bottle  is  to  be  filled  with  water  at  a  tem- 
perature of  about  60°  F.,  for  a  cement  mixed  at  that  temperature  will 
give  the  best  results.  In  case  the  day  is  too  hot  and  humid  such  a 
procedure  may  not  be  best,  as  the  cool  bottle  in  such  an  atmosphere 
will  have  moisture  condense  upon  its  surface  and  the  result  be  worse 
than  using  a  slab  at  room  temperature.     Therefore,  the  temperature 


254     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

and  humidity  of  the  atmosphere  must  be  taken  into  consideration.^ 
The  siHcates  are  so  sensitive  that  weather  conditions  may  either  make 
or  mar  an  operation.  A  portion  of  the  powder  should  be  placed  on  one 
end  of  the  slab  and  a  portion  of  the  liquid  at  the  other.  A  small  portion 
of  the  powder  should  be  incorporated  in  the  liquid  and  mixed  thoroughly 
with  an  agate  spatula.  One  made  of  any  of  the  metals  will  be  likely 
to  discolor  the  filling  by  the  abrasion  of  its  surface  and  the  incorpora- 
tion of  the  abraded  particles  into  the  mass  of  the  filling.  A  spatula  of 
tantalum,  however,  may  be  used,  for  it  is  of  such  hard  consistency  that 
it  will  suffer  little  abrasion  and  will  not  discolor  the  cement. 

The  mix  should  be  of  a  soft  putty  consistency  and  should  be  thor- 
oughly spatulated  until  the  mass  of  powder  is  perfectly  incorporated 
in  the  liquid. 

The  instruments  that  are  used  for  the  insertion  of  the  silicate 
should  be  not  of  steel  but  of  ivory,  tortoise  shell  or  tantalum.  The 
tantalum  instruments  are  preferred  as  they  are  stiffer  and  can  be 
made  of  more  convenient  shapes  and  can  be  used  with  more  force  than 
the  others.  The  cement  should  be  placed  in  the  cavity  as  quickly  as 
possible  and  shaped  to  form  before  crystallization  begins,  and  should 
not  be  disturbed  after  it  begins  to  set,  for  if  it  is  the  forming  crystals 
will  be  broken  up  and  the  best  results  not  obtained. 

After  the  cement  has  hardened  it  may  be  trimmed  to  form  after 
which  it  should  be  allowed  to  set  under  the  protection  of  the  rubber 
dam  for  at  least  fifteen  minutes,  when  it  may  be  coated  with  the  varnish 
furnished  by  the  manufacturers  or  by  a  varnish  made  by  the  solution 
of  white  rosin  in  ether.  The  rubber  dam  may  then  be  removed  and  the 
patient  dismissed. 

The  silicates  may  be  used  in  the  form  of  a  crown  for  the  restoration  of 
badly  broken-down  teeth  by  the  use  of  the  Caulk' s  tooth  forms.  These 
are  hollow  celluloid  forms  of  the  teeth,  and  are  so  made  that  when 
the  proper  form  is  selected  it  may  be  filled  with  the  enamel  in  the 
proper  shades  to  suit  the  case,  making  the  gingival  portion  a  little 
yellow,  the  central  portion  of  the  color  of  the  approximating  teeth  and, 
if  called  for,  shading  the  incisal  with  a  little  blue  to  simulate  the  enamel 
that  is  without  a  dentin  background,  as  is  the  case  in  long  thin  incisors. 
In  making  these  mixes  at  the  same  time  it  will  be  necessary  to  have  an 
assistant  make  one  mix  while  the  operator  makes  the  other. 

The  form  filled  with  the  suitable  silicate  is  pressed  down  upon  the 
prepared  tooth  and  allowed  to  harden.  It  should  be  kept  dry  for  fifteen 
or  twenty  minutes  and  then  the  patient  dismissed  with  the  celluloid 
form  in  position,  with  instructions  to  call  the  following  day  to  have  it 

1  The  reader  is  referred  to  Chapter  VII  for  a  further  discussion  of  this  subject. 


MANAGEMENT  OF  CHILDREN'S  TEETH  255 

removed  and  the  crown  polished,  if  necessary.  If  the  work  has  been 
done  carefully  there  will  be  very  little  polishing  necessary,  for  the 
polished  surface  of  the  celluloid  form  will  give  a  high  polish  to  the 
enamel  crown. 

In  the  same  manner,  broken  bridge  facings  may  be  repaired  with  the 
same  material.  In  this  case  the  forms  are  not  entire  crowns,  but 
merely  the  facings,  which  may  be  selected  for  the  case  and  filled  with 
the  suitable  material  and  pressed  to  place  over  the  pins  in  the  backing 
of  the  broken  facing.  When  the  cement  has  hardened  the  form  is 
removed,  the  facing  coated  with  varnish  and  the  patient  dismissed. 
In  these  and  many  other  ways  that  will  suggest  themselves  to  the 
ingenious  dentist  the  silicates  fill  a  large  place  in  the  practice  of  a  busy 
man  and  serve  the  patient  very  well  indeed.  But  to  reiterate,  a  restora- 
tion of  any  kind  made  with  a  cement  is  not  permanent  if  the  cement  is 
exposed  to  the  fluids  of  the  mouth  and  the  friction  of  mastication. 

The  oxyphosphates  are  valuable  for  all  kinds  of  temporary  work, 
the  sealing  in  of  medicaments  in  root  treatment,  the  treatment  of 
children's  teeth  and  the  setting  of  inlays,  crowns  and  bridges. 

The  inlay  regime  has  brought  the  cements  into  use  more  than  ever 
before,  and  protected  by  a  perfectly  fitting  inlay,  this  makes  about  as 
near  the  ideal  restoration  of  broken-down  tooth  tissues  as  modern 
science  has  yet  attained. 

For  an  inlay  it  is  necessary  to  mix  the  cement  a  little  thinner  than  for 
a  filling,  for  if  the  mix  is  made  too  stiff  the  inlay  will  not  go  to  place. 
The  mix  should  be  of  a  heavy  cream  consistency  about  as  stifle  as  will 
drop  from  the  spatula  when  held  up  from  the  slab.  It  should  be  placed 
in  a  dry  cavity,  but  the  modern  hydraulic  cements  of  the  oxyphosphate 
type  do  not  need  to  be  kept  dry  after  the  inlay  is  seated.  The  fact  is 
the  makers  say  that  it  is  necessary  to  have  the  addition  of  moisture 
to  perfect  the  setting.     (See  Chapter  VII.) 

For  the  setting  of  crowns  and  bridges  the  oxyphosphates  are  also 
used  and  are  found  the  best  medium  for  that  purpose,  for  their  tenacity 
is  such  that  they  add  somewhat  to  the  retention  of  the  crown.  It  will 
be  found  necessary  to  make  the  mix  for  crowns  and  bridges  thinner 
than  for  fillings,  but  a  little  stiff er  than  that  used  for  the  setting  of  the 
inlay. 

THE  MANAGEMENT  OF  CHILDREN'S  TEETH. 

The  first  point  in  the  management  of  the  teeth  of  children  should  be 
the  instruction  of  the  parents  in  the  importance  of  the  temporary  or 
deciduous  teeth,  for  very  few  of  them  realize,  in  any  degree,  the 
necessity  for  maintaining  the  deciduous  teeth  in  any  sort  of  health. 
The  frequent  expression,  "Oh!  they  are  only  first  teeth  and  he  will 


256     CAVITY  PREPARATION  AND   THE   FILLING  OF   TEETH 

soon  lose  them,"  is  indicative  of  the  carelessness  with  which  the 
average  parent  views  the  ravages  of  decay  in  relation  to  the  first, 
deciduous  teeth.  Therefore  it  should  be  the  business  of  the  dentist 
to  institute  a  campaign  of  education  among  the  parents  of  children  to 
instruct  them  in  the  importance  of  the  deciduous  teeth  in  relation  to 
the  comfort,  health  and  development  of  the  child.  From  the  manner 
in  which  many  dentists  dismiss  the  subject,  it  is  evident  that  they  also 
need  a  little  enlightenment  upon  the  subject,  or  at  least  should  have 
their  conscience  awakened  by  being  taught  the  baneful  effects  upon  the 
growing  child  of  a  mouth  full  of  diseased  teeth. 

In  this  day,  when  we  are  taught  that  many  of  the  ills  of  the  human 
family  are  directly  traceable  to  foci  of  infection  in  and  about  the 
teeth,  we  should  not  overlook  the  fact  that  an  abscess  at  the  root  of  a 
deciduous  tooth  harbors  the  same  organisms  that  make  the  one  on  a 
permanent  tooth  dangerous.  If  these  organisms  are  dangerous  to  the 
adult  they  are  in  even  a  larger  degree  dangerous  to  the  child.  Not 
only  so,  but  the  fact  that  the  teeth  in  decaying  cause  irritated  pulps 
with  consequent  pulpitis  and  all  forms  of  toothache,  which  are  as 
painful  to  the  child  as  to  the  adult,  should  make  every  lover  of  children 
do  all  in  his  power  to  avert  the  needless  suffering  that  is  thus  caused. 
That  suffering  by  reason  of  toothache  is  the  cause  of  much  of  the  ill- 
health  of  childhood  is  an  undoubted  fact,  for  the  nervous  system  of 
children  is  easily  upset  and  the  reflex  action  caused  by  a  severe  and 
long-continued  attack  of  toothache  will  frequently  so  disturb  the  nerve 
balance  of  the  child  that  a  severe  illness  and  possible  fatal  result  may 
ensue. 

The  decay  of  the  teeth  causes  an  inability  to  eat  properly,  and  the 
child,  with  a  mouth  full  of  decayed  teeth,  either  refuses  food  or  bolts 
it  whole  or  very  imperfectly  masticates  it.  Food  thus  entering  the 
stomach  of  the  child  is  not  fit  for  digestion  and  the  child  suffers  from 
all  of  the  ills  that  follow  in  the  train  of  digestive  disturbances.  Not 
only  so,  but  the  constant  swallowing  of  the  millions  upon  millions  of 
bacteria  and  their  toxins,  that  are  holding  high  carnival  upon  the 
substance  of  the  teeth,  is  not  conducive  to  the  health  and  development 
of  the  child.  Many  an  adult  today  is  suffering  from  digestive  disturb- 
ances and  faulty  food  habits  that  are  the  result  of  neglected  conditions 
in  the  deciduous  teeth. 

Cavities  in  the  teeth  are  ideal  culture  mediums  for  all  sorts  of  patho- 
genic organisms,  and  the  child  who  has  overcome  an  attack  of  diph- 
theria, scarlet  fever  or  any  other  infectious  disease  becomes  a  carrier 
of  that  disease  by  harboring  the  organism  in  the  cavities  of  the  teeth, 
and  then  expelling  them  in  the  saliva,  in  expectorating,  coughing  or 
sneezmg,  to  the  detriment  of  all  of  the  other  children  m  the  vicinity. 


MANAGEMENT  OF  CHILDREN'S  TEETH  257 

One  of  the  strongest  arguments  for  the  compulsory  exammation  and 
care  of  the  teeth  of  children  is  this  fact.  The  child  with  decayed  and 
diseased  teeth  is  not  only  a  menace  to  himself,  but  also  to  every  child 
with  whom  he  comes  in  contact.  It  may  not  make  very  much  diflfer- 
erence  to  us  how  much  the  children  of  the  poor  may  suffer,  but  when 
we  reahze  the  truth  that  they  will  not  and  do  not  suffer  alone,  but  pass 
on  the  germs  of  their  misery  to  your  child  and  mine,  it  makes  us  think. 

The  future  generation  will  never  be  what  it  could  be  until  the  teeth 
of  the  children  of  this  generation  are  kept  from  the  ravages  of  decay, 
and  the  sooner  the  public  realizes  this  truth  the  sooner  will  the  world 
enter  upon  a  real  foundation  of  the  prevention  of  disease. 

The  first  thing,  then,  in  the  treatment  of  children's  teeth  is  prophy- 
laxis, the  prevention  of  disease.  The  child  should  be  under  the  care  of 
the  dentist  as  soon  as  the  first  teeth  erupt,  and  sometimes  it  is  necessary 
to  see  them  before  the  emergence  of  the  teeth  from  the  gums,  for  if  the 
teeth  do  not  erupt  easily  the  disturbances  to  the  nervous  system  of  the 
child  may  be  very  serious,  even  to  the  point  of  bringing  on  convulsions. 
If  the  gums  are  inflamed  and  tender  and  the  child  irritable  and  crosg^ 
with  every  indication  of  painful  dentition,  it  will  be  good  practice  to 
lance  the  dense  gum  tissue  over  the  erupting  tooth  or  teeth  and  assist 
nature  in  bringing  the  tooth  to  the  surface.  In  doing  this  a  very  sharp 
lancet  should  be  used  and  the  cut  made  in  accordance  with  the  needs 
of  the  case.  If  it  is  an  incisor  a  straight  cut  following  the  incisal  edge 
of  the  tooth  will  be  all  that  is  necessary.  If  a  molar  it  will  be  wise  to 
make  a  cross-cut,  one  from  the  disto-lingual  angle  and  one  from  the 
disto-buccal  angle,  diagonally  across  the  gum  where  the  tooth  is  to 
emerge.  These  two  incisions  will  cross  each  other  at  about  the  point 
of  the  center  of  the  tooth  and  continue  to  the  opposite  angle  from 
whence  they  started. 

It  is  usually  only  necessary  to  lance  one  or  two  teeth  at  a  time,  for 
there  are  not  more  than  four  erupting  at  any  one  time,  and  there  are 
not  many  cases  in  which  all  are  gum-bound.  The  relief  given  to  the 
child  is  usually  almost  immediate  and  the  reflex  symptoms  rapidly 
abate. 

When  the  teeth  have  been  erupted  they  should  be  kept  clean  and  the 
mother  and  nurse  should  be  instructed  in  the  importance  of  so  doing. 
The  cleansing  of  the  teeth  with  a  soft  cloth  will  do  for  the  first  few 
months,  but  as  soon  as  possible  the  child  should  be  accustomed  to  the 
proper  use  of  the  brush.  Simply  sweeping  the  brush  over  the  labial  and 
buccal  surfaces  of  the  teeth  will  do  little  good  and  may  do  much  harm, 
for  it  gives  a  false  sense  of  security  to  the  patient.  A  small  brush 
should  be  obtained,  and  following  the  system  of  Dr.  Charters,  of  Des 
Moines,  Iowa,  the  bristles  at  the  heel  of  the  brush  should  be  cut  oft' 
17 


258     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

with  a  sharp  knife,  leaving  a  tuft  of  bristles  at  the  end.  In  use  the 
brush  should  be  placed  at  right  angles  to  the  teeth  and  the  bristles 
inserted  between  them,  so  that  they  enter  the  interproximate  spaces, 
and  then  the  brush  should  be  rotated  in  such  a  manner  that  the 
bristles  may  scrub  the  approximating  surfaces  of  the  teeth,  just  the 
places  where  the  bacterial  plaques  first  attach  themselves.  If  these 
surfaces  are  kept  clean  there  will  be  no  possibility  of  the  bacteria  form- 
ing the  destructive  plaque,  and  the  teeth  will  not  decay.  After  the 
teeth  have  been  thus  treated  from  the  labial  surface  the  brush  should  be 
inserted  in  the  embrasures  from  the  lingual  surface  and  the  method  of 
cleansing  the  proximate  surfaces  of  the  teeth  followed  from  within  the 
arch.  This  method  cleanses  the  portions  of  the  teeth  that  need  it, 
and  in  addition  to  that  the  friction  of  the  brush  upon  the  septal  tissue 
makes  it  firm,  resistant  and  healthy.  Tooth  pastes  and  mouth  washes 
are  not  essential,  but  a  bland  paste  of  pleasant  taste  and  a  normal  salt 
mouth  wash  are  all  that  are  necessary.^  The  child  should  be  encouraged 
to  rinse  the  mouth  forcibly  after  each  meal,  this  to  be  done  by  holding 
the  lips  together  with  the  fingers  and  then  forcing  the  wash  between 
the  teeth  with  so  much  force  that  it  would  be  sprayed  out  of  the  mouth 
were  not  the  lips  held  tightly  together  with  the  fingers.  A  pleasant 
and  efficient  mouth  wash  may  be  made  at  home  by  taking  one  tea- 
spoonful  of  salt,  one  of  bicarbonate  of  soda  and  ten  drops  of  the  oil 
of  cassia  to  the  pint  of  water;  this  to  be  brought  to  a  boil  and  then 
bottled  for  future  use.  This  wash  is  pleasant  to  the  taste  and  the 
children  usually  like  to  use  it.  Also,  it  makes  them  think  they  are 
using  something  more  than  water,  so  the  psychology  of  its  use  is  good. 

The  children  should  be  brought  to  the  dentist  at  least  every  six 
months  after  the  eruption  of  the  teeth  for  a  cleansing  and  any  repara- 
tive work  that  may  be  necessary.  If  this  is  faithfully  carried  out  there 
will  be  little  danger  of  dental  complications  in  childhood.  In  cleaning 
the  teeth  a  soft  piece  of  wood  should  be  shaped  to  a  point  and  charged 
with  the  flour  of  pumice.  With  this  every  surface  of  the  teeth  should 
be  thoroughly  polished,  all  the  time  making  play  of  it.  Life  to  a  child 
is  one  big  game  and  the  dentist  who  can  enter  into  the  spirit  of  play 
with  them  and  make  the  operation  a  game  will  have  little  difficulty  in 
the  management  of  children. 

Incipient  decay  in  the  pits  and  fissures  of  the  teeth  may  be  treated 
with  nitrate  of  silver.  The  Howe  ammonium  solution  is  of  splendid 
service.  The  silver  solution  should  be  infiltrated  into  the  defective 
places  in  the  teeth  after  having  dried  the  tooth  and  protected  the 
mouth  with  a  cotton  roll  or  napkin. 

1  The  reader  is  referred  to  Chapter  III  for  a  further  discussion  of  this  subject. 


MANAGEMENT  OF  CHILDREN'S  TEETH  259 

After  the  silver  solution  has  had  a  chance  to  soak  into  the  fissure, 
reduce  the  silver  with  eugenol.  This  will  cause  a  deposit  of  metallic 
silver  within  the  defect  and  will  not  only  sterilize  the  cavity  but  will 
infiltrate  the  decayed  process  with  metallic  silver  and  protect  it  from 
a  recurrence  of  decay  for  some  time  at  least.  The  process  of  using  the 
silver  solution  and  reducing  with  eugenol  should  be  repeated  several 
times  to  make  the  deposit  as  heavy  as  possible.  In  case  the  decay  has 
progressed  so  far  that  an  appreciable  cavity  is  in  evidence  the  enamel 
margins  should  be  cut  away  as  much  as  necessary  and  as  much  of  the 
decay  removed  as  can  be  without  pain  to  the  patient.  It  is  desirable 
to  cause  as  little  pain  to  the  patient  as  consistent  with  the  preservation 
of  the  teeth.  This  is  particularly  true  of  the  first  few  times  they 
are  operated  upon.  After  the  confidence  of  the  child  is  won  he  will 
bear  a  great  deal  if  he  is  told  honestly  that  it  will  hurt  some.  Never 
deceive  a  child,  for  if  his  confidence  is  once  destroyed  it  will  be  impos- 
sible to  do  much  with  him.  After  removing  as  much  decay  as  possible, 
sterilize  that  remaining  with  the  silver  solution  and  fill  with  one  of  the 
cements,  gutta-percha  or  copper  amalgam. 

Cement  in  children's  teeth  is  very  valuable,  in  that  the  operator  is 
enabled  to  introduce  it  into  a  cavity  which  would  not  retain  a  metal 
filling.  By  reason  of  its  adhesiveness  it  will  maintain  itself  in  a  shallow 
cavity  for  a  considerable  time,  and  is  a  very  valuable  material  with 
which  to  temporize  in  the  treatment  of  children.  It  is  much  better  to 
make  a  cement  filling  that  will  have  to  be  made  over  in  a  few  months, 
and  not  hurt  the  child,  than  to  make  a  permanent  filling  and  destroy 
the  confidence  of  the  child  in  dentists  forever. 

The  engine  should  be  used  very  sparingly  indeed  in  the  treatment  of 
children's  teeth  for  several  reasons:  (1)  because  of  the  dread  children 
have  for  the  instrument,  and  (2)  because  the  use  of  a  bur  in  the  decidu- 
ous teeth  is  dangerous  in  that  the  pulp  is  very  close  to  the  surface,  and 
a  little  injudicious  cutting  with  a  bur  is  likely  to  penetrate  the  pulp 
chamber  causing  intense  pain  to  the  child  and  the  loss  of  the  pulp.  The 
cavity  preparation  should  be  nearly  all  made  with  hand  instruments, 
and  inasmuch  as  we  are  not  expecting  the  fillings  to  endure  for  a  long 
time,  sufficient  retention  can  be  obtained  for  all  practicable  purposes. 

Gutta-percha  is  also  a  valuable  material  to  use  in  children's  teeth, 
but  should  not  be  used  in  proximo-occlusal  cavities,  for  the  nature  of  the 
material  is  such  that  it  will  jam  into  the  interproximate  space  under 
mastication  and  cause  annoyance  and  pain.  In  occlusal  cavities  or 
proximate  cavities  which  do  not  involve  the  occlusal  surface  its  use  is 
good  practice. 

One  of  the  best  materials  for  use  in  children's  teeth  is  copper  amal- 
gam.    It  is  black  in  color,  but  in  the  posterior  teeth  of  children  that  is 


260     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

of  little  importance.  Its  antiseptic  qualities  and  the  fact  that  it 
does  not  shrink  make  it  most  valuable  in  filling  such  teeth.  The 
fact  that  it  wears  out  in  time  is  an  objection  to  its  use  in  the 
permanent  teeth,  but  it  lasts  long  enough  to  be  of  great  service  in  the 
deciduous  teeth.  Its  physical  characteristics  are  also  in  its  favor,  for 
its  plasticity  enables  the  operator  to  place  it  in  the  child's  tooth  quickly 
and  efHciently, 

In  making  a  proximate  filling  the  contact  point  should  be  maintained 
as  well  as  in  a  filling  for  an  adult,  for  the  same  reason.  The  packing  of 
fibrous  food  into  the  interproximate  space  is  as  much  of  an  irritant  to 
the  child  as  it  is  to  an  adult,  and  the  same  measures  should  be  insti- 
tuted to  prevent  it. 

Unfortunately  the  dentist  does  not  have  control  of  all,  nor  indeed  of 
many  of  his  little  patients,  and  the  first  time  that  he  sees  most  of  them 
is  when  they  are  brought  to  the  office  suffering  with  a  toothache,  and 
in  many  cases  frightened  almost  to  convulsions  with  fear  of  the 
dentist.  In  such  cases  it  requires  the  greatest  tact  and  patience  to 
accomplish  anything  for  the  little  sufferers.  The  only  thing  that 
should  be  done  is  to  attempt  to  relieve  the  pain.  In  case  it  is  a  pulpitis 
this  may  be  done  by  washing  out  the  debris  as  gently  as  possible  and 
avoiding  the  use  of  instruments  except  those  absolutely  required.  The 
food  debris  may  be  washed  out  with  a  warm  solution,  flavored  with  a 
little  oil  of  cassia,  which  will  attract  the  attention  of  the  child  if  he  is 
told  that  it  is  candy  water,  and  he  will  usually  learn  to  like  it  and  even 
to  ask  for  it.  If  it  is  necessary  to  remove  some  of  the  decay,  do  it 
carefully  so  as  not  to  cause  the  slightest  pain,  and  then  flow  into  the 
cavity  a  thin  solution  of  zinc  oxid  in  eugenol.  Over  this  drop  a  thin 
portion  of  an  oxyphosphate  cement,  tamp  it  gently  to  place  with  a 
moist  piece  of  cotton  and  dismiss  the  patient.  The  next  time  be  as 
gentle  as  possible,  all  the  time  gaining  the  confidence  of  the  little  man 
or  woman  and  in  a  short  time  he  will  allow  the  dentist  to  work  at  will 
with  him.  In  cases  of  pulpitis  that  respond  to  treatment  it  may  not  be 
necessary  to  extirpate  the  pulp.  If  the  hyperemia  subsides,  remove  as 
much  of  the  decay  as  possible  without  exposing  the  pulp,  then  thorough- 
ly infiltrate  with  the  silver  eugenol  solution  and  make  a  cement  filling, 
carefully  watching  the  patient  for  symptoms  of  a  dying  pulp.  It  is 
much  better  to  preserve  the  pulp  if  possible,  but  on  the  first  symptom 
of  its  death  the  tooth  should  be  opened  and  the  pulp  removed. 

The  extirpation  of  the  pulp  in  the  teeth  of  children  is  a  difficult  and 
trying  operation.  Arsenic  should  not  be  used  at  all  in  deciduous  teeth. 
If  the  pulp  must  be  devitalized,  it  can  be  accomplished  by  the  repeated 
application  of  phenol,  ammonia  or  formocresol  in  cases  of  a  putrescent 
odor.    In  the  removal  of  the  pulp  and  the  filling  of  the  canal  the  same 


GOLD  INLAY  261 

asepsis  should  be  observed  as  in  the  treatment  of  the  adult  teeth,  for 
the  child  is  susceptible  to  the  same  organisms  and  may  suffer  the  same 
general  diseases  due  to  focal  infections.  If  possible  to  place  the  dam 
it  should  be  done.  But  the  difficulty  of  doing  so  with  a  child  in  the 
treatment  of  deciduous  teeth  is  realized.  If  not  possible,  much  can 
be  accomplished  with  cotton  rolls  and  the  saliva  ejector,  the  assistant 
helping  with  both. 

Howe's  silver  solution  is  invaluable  in  the  treatment  of  the  root 
canals.  The  solution  should  be  introduced  into  the  pulp  chamber  and 
allowed  to  penetrate  the  canals  by  capillary  attraction.  Much  instru- 
mentation should  be  avoided,  for  if  the  solution  is  forced  past  the  apical 
foramen  it  will  cause  an  irritation  that  will  be  difficult  to  relieve.  If 
not  forced  through  by  instrumentation  there  is  little  danger,  however. 
In  the  teeth  of  children  it  is  advisable  to  reduce  the  silver  with  eugenol 
rather  than  use  the  formic  acid  method,  because  of  its  non-irritating 
property.  This  method  seals  the  tubuli  and  sterilizes  them  at  the 
same  time,  after  which  the  canals  can  be  filled.  The  filling  is  accom- 
plished with  Buckley's  euca-percha,  followed  by  a  cone  that  has  had 
the  end  clipped  off'  so  that  it  will  not  penetrate  the  foramen;  the  pulp 
chamber  is  filled  with  gutta-percha  and  the  cavity  finished  with  a 
cement.  Later  on  the  cavity  may  be  filled  with  amalgam  if  desirable. 
All  deciduous  teeth  that  have  had  the  pulp  removed  and  the  root 
canals  filled  should  be  watched  from  time  to  time  to  see  that  no  marked 
destruction  has  taken  place  and  that  the  coming  tooth  in  the  permanent 
set  is  erupting  properly,  for  in  many  cases  the  roots  of  the  deciduous 
teeth  will  not  be  absorbed  and  the  permanent  teeth  will  not  come  into 
their  proper  places  in  the  arch  as  a  consequence.  If  either  happens 
extract  the  deciduous  tooth.  It  is  advisable  for  the  development  of 
the  arch  to  retain  the  deciduous  teeth  as  long  as  nature  intended,  but  if 
infection  or  irregularity  is  likely  to  occur  as  a  consequence  of  the 
retention  of  a  pulpless  tooth  it  is  the  part  of  wisdom  to  choose  the  lesser 
of  the  evils  and  extract  the  offending  tooth.  Abscesses  on  deciduous 
teeth  are  an  indication  that  such  teeth  should  invariably  be  removed. 
It  is  not  wise  to  take  the  chance  of  a  possible  systemic  infection  with  a 
child. 

GOLD  INLAY. 

The  preparation  of  a  cavity  for  the  reception  of  a  gold  inlay  does 
not  differ  materially  from  that  for  a  gold  filling.  The  only  difference 
is  that  a  cavity  for  a  gold  filling  may  be  made  so  that  it  offers  some 
internal  retention  in  the  way  of  undercuts,  which  are  obviously  contra- 
indicated  in  making  a  cavity  for  a  gold  inlay,  for  if  an  undercut  were 
made,  the  wax  pattern  would  not  draw  and,  if  it  did,  the  inlay  would 


262     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

not  go  to  place  when  completed.  Fundamentally,  however,  the  prin- 
ciples of  making  a  cavity  for  a  gold  inlay  are  the  same  as  for  a  gold 
filling.  Therefore,  it  will  not  be  necessary  to  discuss  the  preliminary 
observations  on  cavity  preparation,  as  they  have  been  given  in  the 
article  on  gold  fillings,  to  which  the  reader  is  referred.  The  same 
sequence  of  operation  and  cavity  classification  will  be  followed  in  this 
article. 


a  b 

Fig.  197. — Mesio-occlusal  cavity  in  the  upper  first  molar:  a,  for  gold  inlay;  b,  for  gold  foil. 

The  principles  governing  the  construction  of  a  gold  inlay  are  compre- 
hended in  the  preparation  of  the  cavity;  making  the  model  or  pattern; 
investing  and  burning  out  the  pattern;  casting;  and  cementing  and 
finishing. 


Fig.  198. — Preparation  of  a  cavity  in  the  occlusal  surface  of  a  lower  molar,  and  cross- 
section  thereof,  showing  the  flat  pulpal  wall,  the  parallel  axial  walls  and  the  bevel  of  the 
cavo-surface  angle. 

Cavity  Preparation. — Class  I  cavities  are  prepared  with  flat  seats 
and  parallel  walls.  These  cavities  are  those  occurring  in  the  occlusal 
surfaces  of  molars  and  bicuspids  and  the  buccal  pits  of  molars  and 
lingual  pits  of  the  incisors.     The  buccal  and  lingual  walls  are  cut  out 


GOLD  INLAY 


263 


with  a  cross-cut  fissure  bur,  No.  702,  and  the  pulpal  wall  made  flat 
with  the  same  instrument. 

The  preparation  of  the  cavo-surface  angle  is  a  little  different  from 
that  of  a  cavity  for  a  gold  filling,  for  the  bevel  is  a  little  longer.  This  is 
done  for  the  reason  that  it  makes  a  longer  flange  upon  the  inlay  and  for 


Fig.   199. 


-Occlusal  cavity  in  lower 
first  molar. 


Fig.  200. — -Occlusal  cavity  with  ex- 
tension in  buccal  groove  in  lower  second 
molar. 


the  additional  reason  that  a  short  bevel  on  the  inlay  would  not  have  as 
great  edge  strength  as  a  malleted  filling,  as  the  gold  in  the  filling  is 
harder  than  the  gold  in  an  inlay.  The  bevel  for  the  inlay  should  be 
nearly,  if  not  quite,  the  depth  of  the  enamel  and  should  make  an  angle 
with  the  wall  of  the  cavity  of  about  90  degrees. 


Fig.  201. — Occlusal  cavity  in  upper 
first  molar. 


Fig.  202. — Occlusal  cavity  with  exten- 
sion in  disto-lingual  groove  in  upper  second 
molar. 


There  is  practically  no  difference  in  the  preparation  of  Class  II 
cavities  from  that  for  the  gold  filling.  The  steps  are  made  flat,  the 
walls  parallel  and  the  cavo-surface  angle  is  beveled  all  around.  The 
emphasis  should  be  placed  upon  making  the  walls  parallel,  for  the 
retention  of  an  inlay  depends  a  great  deal  upon  frictional  resistance. 
Dependence  cannot  be  placed  upon  any  internal  retention,  for  that 


264     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

would  militate  against  the  making  of  an  inlay,  and  in  proportion  as  we 
depart  from  the  paralleling  of  the  walls  and  make  the  cavity  cone- 
shaped,  with  the  base  at  the  occlusal  and  the  walls  converging  pulpall}^, 
we  lose  the  frictional  resistance  of  the  walls  of  the  cavity,  and  the 


Fig.  203. — Mesio-occlusal  upper  first  bicuspid. 


Fig.  204. — Mesio-occlusal  upper  first 
molar  extending  to  oblique  ridge. 


Fig. 


205. — Mesio-occlusal  upper  first 
molar  involving  distal  pit. 


Fig.  206. — Mesio-occlusal  lower  first  molar. 


retentive  form  thereof.  Retention  is  secured  by  the  paralleling  of  the 
walls  plus  depth  of  cavity.  If  the  cavity  is  not  of  sufficient  depth, 
there  will  not  be  enough  wall  to  make  resistance  even  though  it  be 
made  parallel.  The  cavity  should  never  be  less  than  the  thickness  of 
the  enamel,  and  usually  considerably  more,  depending  entirely  upon 


GOLD  INLAY  265 

the  amount  of  stress  the  finished  inlay  will  have  to  resist.  All  inlays 
and  fillings  should  be  anchored  in  the  dentin  and  never  in  the  enamel. 
If  there  is  Httle  or  no  occlusion  it  will  be  necessary  only  to  clear  the 
enamel  and  anchor  in  the  dentin,  but  if  the  stress  is  great,  the  cavity 
should  be  cut  proportionately  deeper. 


a  b  c 

Fig.   207. — Mesio-occluso-distal  cavity  in  upper  first  bicuspid:   a,  mesial  view; 
b,  occlusal  view;  c,  distal  view. 

Mesio-occluso-distal  cavities  in  molars  and  bicuspids,  while  following 
the  general  principles  outlined,  may  have  the  mesial  and  distal  walls 
converge  slightly,  as  in  this  class  of  cavities  there  is  sufficient  frictional 
resistance  offered  by  the  great  amount  of  wall  space  to  afford  plenty  of 
retention  and  the  converging  walls  make  the  obtaining  of  the  pattern 
and  the  placing  of  the  inlay  a  much  easier  matter. 


Fig.  208. — -Mesio-occluso-distal  cavity  Fig.  209. — Mesio-occluso-distal  cavity 

in  upper  first  bicuspid  with  buccal  cusp  in  upper  first  bicuspid,    both  cusps  cut 

cut  away  for  protection.  away  for  protection. 

If  there  is  a  weakness  of  the  buccal  or  lingual  walls  it  is  advisable  to 
cut  off  a  portion  of  the  cusps  and  build  the  inlay  over  them  in  order  to 
prevent  the  fracture  of  either  wall  under  stress.  The  inlay  lends  itself 
beautifully  to  this  class  of  operative  procedures  and  many  teeth  that 


266     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

formerly  would  have  been  crowned  are  now  restored  by  the  inlay.  In 
some  instances,  where  much  of  the  dentin  is  gone  and  the  pulp  has  been 
removed,  the  inlay  is  anchored  in  the  pulp  chamber  and  a  subpulpal 
seat  made  for  retention. 


Fig.  210. — Mesio-occluso-distal  cavity 
in  lower  second  molar  with  buccal  cusp 
cut  away  for  protection. 


Fig.  211. — Mesio-occluso-distal  cav- 
ity in  lower  first  molar  with  lingual  cusps 
cut  away  for  protection. 


Class  III  cavities  are  approached  from  the  lingual  surface  and  the 
preparation  differs  considerably  from  that  for  the  gold  filling.  With  a 
fissure  bur.  No.  702,  entrance  is  gained  into  the  cavity  from  the  lingual 
surface  and  the  axial  wall  made  flat,  cutting  to  a  depth  that  will  leave 
a  small  amount  of  dentin  between  the  cavity  and  the  labial  wall  of 
enamel. 


Fig.  212. — Mesio-occluso-distal  cavity  in  upper  first  molar  with  disto-lingual  cusp  cut 

away. 


The  labial  cavity  outline  need  not  be  very  great  if  the  decay  does  not 
demand  it.  The  enamel  on  the  labial  surface  should  be  cut  only  far 
enough  to  cause  the  inlay  to  clear  the  approximating  tooth,  thus 
making  for  a  clean  margin  and  satisfying  the  law  of  extension  for 
prevention.  This  is  done  for  the  purpose  of  hiding  the  gold  as  much 
as  possible  and  also  allowing  a  seat  for  the  inlay,  which  in  this  class 
of  cases  is  against  the  labial  wall.    The  gingival  and  incisal  walls 


GOLD  INLAY  267 

should  be  made  to  slope  slightly  away  from  each  other,  the  gingival 
one  sloping  apically  and  the  incisal  one  incisally,  thus  causing  them  to 
diverge  as  they  approach  the  axial  wall.  This  will  make  a  dovetail 
in  the  preparation  that  will  prevent  any  lateral  displacement  and  will 
allow  the  inlay  to  be  inserted  from  the  lingual  and  from  no  other  direc- 
tion. The  cavo-surface  angle  should  be  beveled  all  around,  but  it  is 
obvious  that  there  can  be  no  real  bevel  made  upon  the  labial  margin 
or  the  wax  would  not  draw.  Fortunately,  we  find  that  the  lay  of  the 
enamel  rods  in  this  position  is  such  that  a  straight  cut  through  the 
tooth  from  labial  to  lingual  will  leave  no  short  rods  upon  the  surface, 
for  the  natural  curve  of  the  tooth  is  such  that  as  the  rods  bend  over  in 
conformity  to  the  shape  of  the  tooth  they  are  cut  in  such  a  way  that 
all  rods  reaching  the  surface  are  those  that  have  their  base  in  contact 


a  be 

Fig.  213. — a.  cavity  for  inlay  in  upper  central  incisor,  lingual  aspect;  b,  same 
cavity,  labial  view;  c,  same  cavity,  proximate  view. 

with  the  dentin.  Therefore  a  straight  cut  through  from  lingual  to 
labial  is  to  all  intents  and  purposes  a  bevel  and  a  flange  will  be  cast 
upon  the  inlay  to  perfect  contact  with  the  enamel.  The  approaching 
of  the  cavity  from  the  lingual  surface  in  the  upper  incisors  affords 
additional  security  in  that  the  stress  of  occlusion  comes  from  the 
lingual  surface  as  the  lower  teeth  impinge  upon  the  upper  from  that 
direction,  which  serves  to  pound  the  inlay  into  the  cavity,  and  there  is 
little  danger  of  its  displacement.  In  the  lower  incisors  this  is  not  true. 
Nevertheless,  we  approach  the  cavity  from  the  lingual,  for  the  labial 
approach  is  of  such  bad  esthetic  form  that  it  is  absolutely  contra- 
indicated.  If  the  incisal  angle  is  not  involved  there  is  little  danger  of 
the  incisal  stress  displacing  an  inlay  in  a  lower  incisor  that  is  made 
from  the  lingual,  for  there  is  really  no  stress  that  reaches  the  inla}';  but 
if  the  incisal  angle  is  involved  it  will  be  necessary  to  obtain  additional 


268    CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

retention  by  making  an  incisal  step  cavity  and  a  sufficiently  deep 
incisal  anchorage. 

In  Class  IV  cavities  we  again  depart  considerably  from  the  conven- 
tional gold-foil  preparation  on  account  of  the  difference  in  retentive 
problems. 

There  are  two  methods  of  obtaining  retention  in  this  class  of  cavities : 
one,  the  incisal  step  and  the  other  the  lingual  dovetail  cavity. 

In  making  the  incisal  step  cavity  a  portion  of  the  incisal  surface  of 
the  tooth  is  ground  down  with  a  carborundum  stone,  as  for  a  gold  foil 
operation,  and  the  outline  form  obtained  on  the  labial  surface  in  the 
same  manner;  but  the  outline  form  on  the  lingual  surface  is  different 
from  that  used  in  the  foil  preparation  by  reason  of  the  fact  that  the 


Fig.  215  Fig.  216 

Figs.  214,  215  and  216. — Mesio-incisal  cavity  in  upper  central:  Fig.  214,  labial  view; 
Fig.  215,  incisal  view;  Fig.  216,  lingual  view. 

internal  preparation  demands  a  treatment  that  makes  the  outline  form 
on  the  lingual  surface  of  different  shape.  The  form  of  an  incisor  or 
cuspid  is  wedge-shaped  or  conical;  therefore,  the  treatment  of  the 
lingual  and  labial  walls  takes  on  the  laws  governing  conic  sections. 
We  know  that  parallel  lines  must  leave  the  cone  at  some  point  and  the 
farther  apart  are  the  lines  the  sooner  will  they  leave  the  cone  in  their 
progress  toward  the  apex  thereof.  We  cannot  make  the  internal  prepa- 
ration of  the  cavity  in  such  a  way  that  there  will  be  any  undercuts 
or  retention  that  will  not  permit  the  wax  to  draw,  therefore  the 
walls  are  made  parallel,  as  far  as  the  shape  of  the  tooth  will 
permit.  But  as  the  lines  must  leave  the  tooth  at  some  place  we 
choose  to  make  the  walls  parallel  at  the  labial  contour  of  the  tooth, 
as  then  the  labial  line  does  not  leave  the  tooth  at  all  but  travels  along 


GOLD  INLAY 


269 


the  long  axis  of  the  tooth  until  it  reaches  the  ineisal  angle.  Therefore, 
the  wall  along  the  lingual  aspect  will  of  necessity  leave  the  tooth  sooner 
than  it  otherwise  would,  and  it  does  so  at  about  the  beginning  of  the 
middle  third  of  the  tooth.  This  method  of  preparation  is  chosen  for 
esthetic  reasons,  for  if  the  line  at  the  labial  were  allowed  to  leave  the 
tooth  at  any  portion  thereof  it  would  make  a  very  unsightly  appearance 
in  the  labial  outline  form.  Inasmuch  as  the  wall  at  the  lingual  leaves 
the  tooth  at  the  middle  third  there  is  very  little  retention  due  to  the 
parallel  walls,  and  it  is  necessary  to  obtain  some  additional  retention. 
This  is  done  by  cutting  a  pit  in  the  pulpal  wall  of  the  preparation  after 
the  cavity  passes  the  lines  of  pulpal  recession,  for  to  cut  a  pit  at  the 
line  of  recession  would  endanger  the  pulp.  The  cavo-surface  angle  is 
beveled  all  around  as  in  any  other  cavity. 


Fig.  217  Fig.  218 

Figs.  217  and  218. — Mesio-incisal  cavity  in  upper  central  incision.    Fig.  217,  lingual 
view.     Fig.  218,  labial  view. 


The  lingual  dovetail  preparation  is  made  by  approaching  the  cavity 
from  the  lingual  surface  as  in  a  simple  Class  III  cavity,  but  as  the  ineisal 
angle  has  been  destroyed  by  the  progress  of  decay,  additional  retention 
is  necessary.  This  is  obtained  in  the  lingual  dovetail  preparation  by 
making  the  cavity  as  nearly  retentive  as  possible,  following  the  method 
of  the  simple  Class  III  preparation  and  then  cutting  an  additional  dove- 
tail in  the  lingual  surface  of  the  tooth.  The  stress  of  mastication  on 
an  upper  incisor  tends  to  drive  the  inlay  farther  into  the  cavity  rather 
than  out  of  it,  and  this  makes  this  preparation  of  particular  value.  It  is 
necessary  to  be  very  careful  not  to  expose  the  pulp  in  the  preparation 
of  the  lingual  dovetail,  as  there  is  danger  of  doing  if  the  cavity  at  this 
point  is  made  too  deep.     It  is  only  necessary  to  cut  the  dovetail  through 


270     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

the  enamel  and  anchor  well  into  the  dentin.  If  this  is  done  there  is  no 
danger  of  pulpal  complications.  If  it  is  thought  necessary  to  make  a 
deeper  preparation  for  the  lingual  dovetail  by  reason  of  extreme  stress 


Fig.  219  Fig.  220 

Figs.   219  and  220. — Disto-incisal  cavity  in  upper  cuspid.     Fig.  219,  labial  view.     Fig. 
220,  lingual  view  showing  lingual  dovetail. 

or  abnormal  occlusion  in  the  region  opposite  the  proximate  surface  in 
which  the  cavity  is  located,  sink  the  dovetail  deeper  into  the  dentin. 
This  will  give  a  preparation  that  will  make  a  thinner  mass  of  gold  as 


Fig.  221  Fig.  222 

Figs.  22 1  and  222. — Mesio-inciso-distal  cavity  in  upper  central  incisor, 

it  passes  over  the  pulpal  area,  but  will  be  deeper  and  heavier  and  sink 
farther  into  the  dentin  when  in  safe  territory.  The  cavo-surface  angle 
is  beveled  all  around  this  cavity  as  well,  observing  the  rule  on  the  labial 


GOLD  INLAY  ■  271 

surface  that  obtains  in  the  preparation  of  the  cavo-surface  angle  in 
Class  III  cavities. 

This  preparation  provides  a,  restoration  that  is  much  more  esthetic 
than  the  incisal  step  cavity,  and  one  that  is  fully  as  likely  to  maintain 
itself  against  the  stress  of  mastication  and  wear. 

The  same  rules  apply  to  cavities  in  the  lower  incisors  and  cuspids,  but 
owing  to  their  diminutive  size  the  preparation  is  more  difficult  and  calls 
for  a  larger  degree  of  patience  and  skill  to  accomplish  the  desired  result. 

Class  V  cavities  occurring  in  the  gingival  thirds  of  any  of  the  teeth 
are  treated  much  the  same  as  like  cavities  in  the  gold-filling  series.  The 
outline  forms  and  the  axial  walls  are  the  same,  the  only  difference  being 
in  the  preparation  of  the  mesial,  distal,  gingival  and  occlusal  walls. 
These  will  not  admit  of  any  undercuts  and  must  be  made  as  nearly 
parallel  as  the  skill  of  the  operator  will  permit.  The  departure  from 
the  parallel  walls  will  proportionately  make  for  a  lack  of  retention,  and 
while  there  is  practically  no  stress  that  falls  upon  inlays  in  this  position, 
it  is  a  fact  that  if  there  is  not  sufficient  retention  these  inlays  will  fall 
out.  The  saucer  preparation  is  decidedly  contra-indicated  in  making 
a  gold  inlay.     The  cavo-surface  angle  is  beveled  all  around  the  cavity. 

Making  the  Pattern. — Any  good  wax  that  is  hard  at  mouth  tempera- 
ture and  perfectly  disappears  under  the  amount  of  heat  to  which  it  is 
thought  desirable  to  submit  the  investment  may  be  used.  It  is  pref- 
erable to  use  one  that  is  hard  at  mouth  temperature,  as  all  of  the  steps 
of  making  the  pattern,  investing,  etc.,  should  be  carried  out  at  the  same 
temperature,  and  if  a  wax  were  used  that  was  so  soft  that  it  required 
a  dash  of  cold  water  to  harden  it,  it  would  shrink  so  much  that  a  good 
pattern  would  not  be  obtained.  Heat  expands  and  cold  contracts; 
therefore  if  the  pattern  is  to  be  a  perfect  reproduction  of  the  cavity 
it  must  be  handled  at  as  nearly  the  same  temperature  throughout  the 
operation  as  it  is  possible  to  do. 

The  wax  may  be  warmed  in  any  way  that  is  convenient  but  should 
not  be  melted  in  the  warming.  If  softened  over  a  flame  it  should  be 
held  high  enough  above  the  heat  so  that  it  softens  slowly  and  should 
be  constantly  turned  and  watched  to  see  that  it  does  not  melt.  After 
a  little  trial  the  color  of  the  wax  will  be  the  index  to  the  eye  of  the 
operator  of  the  degree  of  softness. 

The  wax  may  also  be  softened  in  warm  water  of  about  130°  F.  A 
convenient  way  to  do  this  is  to  obtain  a  large  flat  cork  and  thrust  a 
number  of  pins  through  the  cork.  Upon  these  pins,  portions  of  the 
wax  may  be  impaled  and  the  cork  then  inverted  in  a  glass  of  water  of 
the  proper  temperature.  In  a  short  time  the  wax  will  be  of  the  right 
consistency  to  use.  Dr.  Taggart  has  invented  a  very  valuable  instru- 
ment which  is  designed  to  keep  the  wax  at  the  proper  temperature. 


272     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

The  wax  should  be  drawn  to  an  elongated  cone,  the  apex  of  which  is 
slightly  softened  a  little  more  than  the  rest  of  the  wax  by  holding  it  for 
a  moment  over  a  flame:  this  for  the  purpose  of  making  a  softer 
portion  of  wax  to  be  inserted  into  the  cavity  and  the  harder  part  to  act 
as  a  piston  to  force  the  wax  mto  every  part  of  the  cavity.     Pressure  should 


Fig.  223. — Taggart  automatic  heater  for  casting  wax. 

be  made  upon  the  wax  from  every  direction  and  maintained  until  the 
wax  is  hard.  This  pressure  is  obtained  by  using  the  index  finger  and 
thumb  of  the  left  hand  on  the  lingual  and  buccal  sides  of  the  tooth  if  a 
molar  or  bicuspid,  and  on  the  lingual  and  labial  if  an  incisor  or  cuspid. 
This  forms  a  matrix  into  which  the  wax  is  forced  by  the  pressure  of  the 


GOLD  INLAY  273 

index  finger  or  thumb  of  the  right  hand  as  it  presses  the  wax  into  the 
cavity.  This  pressure  is  necessary  as  the  wax  shrinks  in  hardening 
and  as  the  pressure  is  maintained  more  wax  is  forced  into  the  cavity 
to  take  the  place  of  the  shrunken  portions,  thus  obviating  a  discrepancy 
and  a  more  nearly  perfect  reproduction  of  the  cavity  is  obtained.  After 
the  wax  has  hardened  it  may  be  carved  to  form.  It  is  not  advisable 
to  allow  the  patient  to  bite  into  the  wax  to  obtain  the  occlusion,  for  the 
wax  has  now  hardened  and  biting  into  it  will  disturb  the  adaptation. 
The  pattern  should  be  carved  to  occlusion  and  anatomic  form.  The 
patient  may  try  the  occlusion  very  easily  from  time  to  time  if  thought 
desirable,  but  the  skillful  operator  will  not  need  much  of  that,  for  he 
will  know  his  dental  anatomy  so  well  that  if  there  is  no  abnormal  occlu- 
sion he  will  have  very  little  difficulty  in  carving  to  form  and  occlusion. 
If  there  is  an  abnormality  of  occlusion,  or  if  for  any  other  reason  the 
operator  desires  to  obtain  the  direct  occlusion  of  the  opposing  teeth, 
he  may  do  so  by  warming  slightly  the  occlusal  surface  of  the  wax  with 
a  warm  ball  burnisher  or  the  hot-air  syringe,  then  allowing  the  patient 
to  bite  into  the  warm  wax.  The  body  of  the  wax  being  hard  and  the 
surface  soft  there  will  be  no  danger  of  the  distortion  of  the  pattern. 
One  of  the  best  instruments  to  use  in  carving  the  proximate  surface  of 
the  pattern,  and  especially  that  portion  near  the  gingival  margin,  is  a 
large  sickle-shaped  exploring  instrument,  the  fine  prong  of  which  can  be 
inserted  into  the  interproximate  space  and  the  wax  carved  out  at  will. 
It  is  also  convenient  in  obtaining  the  adaptation  at  the  gingival  below 
the  free  margin  of  the  gum  and  cutting  off  any  overhanging  wax.  The 
occlusal  surface  should  be  carved  to  anatomic  form,  being  careful  to 
restore  the  marginal  ridge.  The  inlay  lends  itself  beautifully  to  the 
artistic  reproduction  of  all  of  the  markings  of  the  tooth,  and  an  impres- 
sion taken  of  the  tooth  after  the  inlay  is  in  place  should  look  as  though 
it  were  the  perfect  tooth  instead  of  a  restoration  thereof. 

When  the  carving  is  finished  the  whole  pattern  should  be  washed 
with  the  oil  of  cajuput,  which  will  smooth  the  surface  by  slightly  dis- 
solving a  film  of  the  wax. 

In  removing  the  model  a  sprue  wire  of  the  proper  size  may  be  warmed 
and  allowed  to  melt  its  way  into  the  pattern  and  kept  there  until  it  is 
perfectly  cool  and  the  wax  around  it  has  hardened,  when  the  pattern 
may  be  lifted  out  of  the  cavity  very  easily.  Or  if  a  curved  explorer  be 
used  the  point  should  be  inserted  into  the  inlay  about  where  the  contact 
should  be  and  the  pattern  carefully  lifted  out.  Force  should  never  be 
used  in  dislodging  the  pattern,  for  to  do  so  will  endanger  the  perfection 
of  the  impression.     A  slight  distortion  will  spoil  the  entire  operation. 

If  the  model  has  been  made  for  a  proximo-occlusal  cavity  it  is  mse  to 
take  a  shaving  of  the  wax  where  it  comes  in  contact  with  the  occlusal 
18 


274     CAVITY  PREPARATION  AND   THE  FILLING  OF   TEETH 

step.  In  the  preparations  it  will  be  noticed  that  there  are  no  shelves 
in  the  cavity  on  which  the  inlay  may  ride,  and  all  of  the  lines  of  the 
preparation  flow  into  the  cavity,  so  that  if  the  inlay  did  not  reach  the 
gingival  portion  of  the  cavity  through  some  slight  shrinkage  of  the  wax 
or  gold  it  would  sink  down  into  the  cavity  until  it  rested  on  the  gingival 
seat  if  it  were  not  for  the  occlusal  step.  Therefore,  the  relieving  of  the 
wax  at  that  point  will  allow  any  descrepancy  at  the  gingival  to  be 
corrected  by  the  inlay  seating  a  little  deeper  into  the  cavity,  thereby 
making  a  perfect  adaptation  at  all  of  the  margins. 


Fig.  224. — Position  of  hands  while  inserting  warmed  sprue  into  wax  pattern  after  it  has 
been  removed  on  an  explorer. 

The  pattern  should  be  invested  as  soon  as  removed  from  the  tooth 
to  prevent  any  movement  of  the  wax  through  any  change  of  tempera- 
ture that  it  might  encounter  in  lying  around  the  office  waiting  for  the 
investment.  The  pattern  should  be  washed  with  a  soft  camel's  hair 
brush,  using  peroxide  of  hydrogen,  alcohol  or  soap  and  water — to 
remove  any  oily  or  muciferous  materials  from  its  surface  so  that  the 
investing  material  will  more  easily  adapt  itself  to  the  wax.  The 
water  in  which  the  investing  compound  is  mixed  should  be  the 
same  temperature  as  that  used  to  cool  the  wax  while  carving  to  avoid 
a  change  in  the  volume  of  the  wax. 


Fig.  225. — Taggart  measuring  device  for  investing  material  and  water;  large  end  for 
investing  material,  small  end  for  water. 


Any  good  investing  compound  may  be  used,  or  the  operator  may 
make  one  himself  that  is  very  satisfactory  by  taking  3  parts  by  measure 
of  finely  pulverized  silex  to  1  part  of  plaster  of  Paris,    This  should  be 


GOLD  INLAY 


275 


thoroughly  mixed  together.  It  may  be  mixed  by  taking  an  ordinary 
flour-sifter,  such  as  housekeepers  use  in  making  bread,  and  sifting  the 
mix  through  this  three  or  four  times,  when  a  homogeneous  mass  will 


Fig.  226. — Position  of  plaster  bowl  while  it  is  being  revolved  and  jolted  on  the  bench. 


Fig.   227. — Taggart  automatic  mixing  device  for  investing  material  and  water. 


be  obtained.  A  balance  or  some  kind  of  measuring  device  should 
always  be  used  so  that  the  proper  proportions  of  the  investing  material 
and  water  may  be  used  each  time.    The  mix  should  be  thoroughly 


276     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

spatulated  and  then  the  bowl  turned  around  and  around,  at  the  same 
time  jolting  it  on  the  bench  to  cause  the  bubbles  in  the  mix  to  rise  to 


Fig.  228. — Automatic  mixer  for  investing  material  and  water  attached  to  ordinary 
laboratory  lathe.     (Suggested  by  Taggart.) 


Fig.  229. — Taggart's  crucible  former  with  sprue  inserted  into  the  wax  and  into  crucible 
former  ready  for  investing. 


Fig.  230. — Inlay  covered  with  investing 
material  previous  to  placing  ring  on  cruci- 
ble former. 


Fig.  231. — Casting  ring  filled  with 
hardened  investing  material,  and  cru- 
cible former  and  sprue  removed. 


BURNIXG  OUT  OF   THE  PATTERN  277 

the  surface  and  break,  thus  obviating,  to  a  great  extent,  the  danger  of 
bubbles  upon  the  pattern,  with  a  consequent  ball  of  gold  cast  on  the 
inlay  where  the  bubble  appeared  on  the  pattern  (Figs.  226, 227  and  228) . 
The  pattern  on  its  sprue  is  placed  in  a  crucible  former  supplied  with  the 
casting  machine  used  and  the  investing  compound  is  painted  upon  the 
sui'face  (Figs.  229,  230  and  231).  Great  care  should  be  used  to  see  that 
the  investing  compomid  is  evenly  and  thoroughly  adapted  to  every 
surface  and  inequality  of  the  pattern,  repeatedly  blowing  the  invest- 
ment off  of  the  pattern  and  repainting,  to  be  sure  there  are  no  air 
bubbles  adhering  to  its  surface.  The  flask  should  be  inverted,  placed 
on  a  piece  of  paper  and  filled  vdih  the  compound,  and  the  pattern  as  it 
is  painted  with  the  investing  material  should  be  slowly  inserted  into 
the  mass,  all  the  time  vibrating  the  pattern  as  it  sinks  into  the  in- 
vestment, to  clear  it  of  any  air  that  might  attach  to  its  surface. 
The  investment  should  be  allowed  to  harden,  but  not  remam  too  long 
before  the  burning  out  is  begmi. 

THE  BURNING  OUT  OF  THE  PATTERN. 

One  of  the  most  important  parts  of  the  entire  operation  is  that  of 
bmiiing  out  the  wax.  It  is  necessary  to  dissipate  the  pattern  in  order 
to  make  the  mold  for  the  reception  of  the  gold,  but  too  great  a  degree 
of  heat  vnll  disintegrate  the  plaster  and  cause  a  distortion  of  the 
finished  inlay.  ]More  misfits  are  caused  by  the  injudicious  use  of  heat 
in  the  bm-ning  out  of  the  wax  than  any  other  cause.  A  flame  should 
never  touch  the  investing  material  or  flask  and  the  temperature  should 
never  rise  above  320°  F.  "\Mien  the  wax  is  dissipated,  allow  the  flasks 
to  cool  perfect!}'  and  cast  cold  (Fig.  232). 

In  casting  gold  into  a  mold  as  small  as  one  must  be  in  order  to  make 
an  inlay  for  a  human  tooth  it  is  necessary  to  use  some  force  in  order  to 
cause  the  metal  to  flow  into  the  mold.  It  is  also  necessary  to  resort 
to  some  method  m  making  the  model  that  is  a  departure  from  the  usual 
method  of  making  molds,  that  is,  the  method  of  using  separable  flasks 
and  making  the  mold  in  these  flasks,  then  separating  the  flask  and 
removing  the  model,  then  replace  the  separate  parts  of  the  flask  in 
immediate  contact  and  cast.  In  the  case  of  an  article  as  small  as  the 
inlay,  and  one  that  requues  the  exactness  of  duplication,  the  separable 
flask  is  out  of  the  question;  therefore  use  is  made  of  the  principle  of 
the  disappearing  model.  The  model  should  be  made  of  a  material  that 
would  disappear  under  the  influence  of  heat  and  then  mto  the  mold  so 
made  the  melted  metal  is  forced.  There  are  a  number  of  devices  for 
casting  the  inlay.  The  first  to  be  considered  is  the  Taggart  machme 
(Fig.  233).    This  is  automatic  in  action  and  consists  of  a  stand  for  the 


278    CAVITY  PREPARATION  AND  THE  FILLING  OF  TEETH 

reception  of  a  nitrous  oxid  gas  cylinder,  which  is  used  for  the  purpose 
of  making  the  oxyhydrogen  flame  to  be  used  in  melting  the  gold  and 
also  for  the  purpose  of  making  pressure  with  which  to  force  the  gold  into 
the  mold.  On  the  same  base  is  located  the  receptacle  for  the  flask 
containing  the  mold.  This  seat  for  the  flask  is  immediately  under  a 
movable  disk  which  is  actuated  by  a  lever  which  forces  it  down  upon 
the  flask,  completely  closing  it.  When  the  lever  closes,  the  flask  also 
automatically  throws  the  blowpipe  away  from  the  crucible  contained 


Fig.   232. — Taggart  automatic  gas  apparatus  for  burning  out  the  wax.^ 


in  the  upper  part  of  the  flask  in  which  the  gold  is  melted,  and  releases 
the  gas  from  the  cylinder,  which  by  its  pressure  immediately  forces 
the  molten  gold  into  the  flask,  thereby  filling  the  mold  with  gold  and 
completing  the  operation  of  casting. 

The  advantage  of  the  Taggart  machine  is  its  automatic  action,  and 
having  all  the  operations  of  casting,  such  as  the  blowpipe,  release  of 

1  Several  electric  devices  have  been  designed  for  burning  out  the  wax,  but  none  seem 
to  have  been  developed  to  a  greater  accuracy  than  the  gas  device. 


BURNING  OUT  OF   THE  PATTERN 


279 


19         -      17  15 

Fig.  233. — Taggart  casting  appliance. 


Fig.  234. — Monson's  centrifugal  casting  machine. 


280     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

the  pressure  principle,  etc.,  in  the  same  machine,  the  art  of  casting  is 
quite  simple.  Besides,  it  enables  the  operator  to  retain  pressure  upon 
the  casting  as  long  as  necessary,  a  very  essential  part  of  the  casting 
principle. 

Another  very  effective  method  is  the  centrifugal  one  (Fig.  234). 
This  method  takes  advantage  of  the  force  that  causes  all  matter  to  fly 
off  at  a  tangent  when  revolved.  The  machine  consists  of  an  arm  that 
revolves  around  a  central  base  of  some  kind;  the  arm  is  actuated  by 
a  spring  or  geared  wheel,  which  on  being  turned  rapidly  causes  the  arm 
to  revolve.  At  the  end  of  the  arm  is  placed  a  receptacle  for  the  flask. 
The  gold  may  be  melted  in  a  crucible  in  the  top  of  the  flask,  as  in  some 
machines,  or  it  may  be  melted  in  a  crucible  placed  in  front  of  the 
orifice  of  the  flask.  In  either  case,  when  the  gold  is  melted  and  the 
machine  actuated,  as  the  flask  begins  to  revolve  the  gold  is  thrown  into 
the  flask  and  held  there  by  centrifugal  force.  This  method  of  casting 
is  very  popular  and  beautiful  results  are  obtained  by  its  use.  Its 
advantages  are  simplicity  of  operation,  possibility  of  retaining  pressure, 
and  in  the  machines  that  have  a  crucible  away  from  the  flask  itself, 
the  possibility  of  melting  the  gold  without  heating  the  flask  or  invest- 
ment— a  very  desirable  feature. 

The  suction  method  is  an  adaptation  of  the  air-pressure  principle, 
but  instead  of  using  direct  pressure,  atmospheric  pressure  is  used,  by 
exhausting  the  air  in  the  flask  and  thereby  causing  the  pressure  of  the 
atmosphere  to  force  the  gold  into  the  mold.  The  machine  consists 
of  a  vacuum  chamber,  from  which  the  air  is  exhausted  by  an  air  pump, 
a  table  upon  which  the  flask  rests,  which  is  connected  to  the  vacuum 
chamber  by  a  pipe  to  which  is  attached  an  air  valve,  which  releases  the 
vacuum  when  desired.  The  flask  must  rest  upon  the  vacuum  table 
with  a  contact  that  is  perfectly  air  tight,  or  the  vacuum  will  not  be 
communicated  to  the  flask  but  will  be  dissipated  by  the  entrance  of 
air  through  the  leak  between  the  table  and  flask.  This  method  is 
popular  with  some  operators  and  good  results  are  obtained  with  it,  but 
it  is  not  so  convenient  nor  simple  as  either  of  the  other  methods. 

There  are  several  crude  methods  that  are  used  with  home-made 
machines,  using  the  principle  of  steam  and  mechanical  pressure.  The 
steam-pressure  method  consists  of  heating  the  gold  in  a  crucible  in  the 
flask  and  when  melted  forcing  a  wet  asbestos  pad  on  the  flask,  which 
seals  it,  and,  by  the  action  of  the  heat  contained  in  the  melted  gold, 
produces  steam  which  forces  the  gold  into  the  mold.  This  method  is 
very  uncertain  and  the  same  amount  of  pressure  is  never  obtained  at 
two  consecutive  castings,  owing  to  the  difference  of  heat  and  the 
amount  of  moisture  contained  on  the  pad.  At  best  it  is  an  unreliable 
method.     The  mechanical  pressure  method  consists  of  making  a  pad  of 


FINISHING  THE  INLAY  281 

molding,  and  upon  the  gold  being  melted  the  pad  is  forced  into  the 
crucible,  when  it  seals  the  top  of  the  flask  and  then  by  reason  of  its 
softness  is  forced  deeper  into  the  crucible  and  the  gold  is  forced  into  the 
mold.  This  method  is  the  least  desirable  of  any  and  should  not  be 
used,  if  possible  to  make  use  of  any  other. 

When  it  is  said  to  cast  cold  it  is  meant  to  cast  cold  and  not  to  heat  up 
the  flask  to  a  red  heat  in  making  the  cast,  as  is  the  habit  of  some. 
The  flask  should  be  so  cool  after  the  cast  is  made  that  it  can  be  picked 
up  immediately  in  the  fingers.  In  order  to  accomplish  this  a  blowpipe 
must  be  used  and  the  small  flame  directed  upon  the  gold  nugget  and 
not  allowed  to  touch  any  part  of  the  flask  or  investment  compound. 
If  a  centrifugal  machine  is  used  the  gold  can  be  fused  in  a  crucible 
away  from  the  flask  in  some  machines,  and  when  melted  the  spring  is 
released  and  the  molten  gold  thrown  into  the  cold  flask.  Pressure 
should  be  maintained  for  at  least  one  minute  in  order  to  force  additional 
gold  into  the  mold  as  the  fused  gold  takes  on  the  solid  state.  Experi- 
ments conducted  by  Dr.  Weston  A.  Price  have  appeared  to  demon- 
strate that  up  to  a  certain  point  additional  gold  will  flow  into  the 
freezing  mass,  thereby  reducing  shrinkage  to  the  minimum.  The 
breaking  away  of  the  sprue  from  the  inlay  and  the  pitting  of  the  inlay 
at  or  near  the  insertion  of  the  sprue  wire  are  sure  indications  that 
pressure  has  not  been  maintained  sufficiently  long  to  allow  the 
compensation  of  additional  fused  gold  to  the  freezing  mass. 

The  inlay  should  be  allowed  to  cool  slowly  before  the  flask  is  opened. 
When  cold  remove  the  inlay,  wash  and  pickle  in  hydrofluoric  acid, 
boil  in  hydrochloric  acid  or  heat  and  drop  into  a  50  per  cent,  solution 
of  sulphuric  acid,  and  the  inlay  is  ready  for  finishing. 

FINISHING  THE  INLAY. 

The  inlay  should  be  partially  finished  before  it  is  tried  in  the  cavity. 
If  the  model  or  pattern  has  been  well  made  there  will  be  little  finishing 
to  be  done,  as  the  casting  will  be  like  the  pattern.  The  sprue  should 
be  cut  off  and  the  sanded  finish  smoothed  with  a  disk;  then  it  should  be 
placed  in  the  cavity  and  malleted  to  place.  If  it  does  not  go  to  place 
perfectly  it  should  be  removed  and  search  made  for  any  bubble  or  fault 
in  the  investment  that  might  militate  against  its  perfect  adaptation 
to  the  walls  of  the  cavity.  When  perfectly  adapted  it  should  be 
burnished  toward  the  walls  all  around  the  cavity,  in  order  to  make  sure 
that  the  adaptation  is  perfect.  An  inlay  that  is  not  perfect  will  save 
the  tooth  for  a  time  because  the  cement  will  fill  up  the  defect,  but  the 
operator  who  depends  upon  a  bruised  reed  of  that  kind  for  the  security 
of  his  operations  will  surely  come  to  grief.     An  inlay  that  shows  a 


282     CAVITY  PREPARATION  AND   THE  FILLING  OF  TEETH 

discrepancy  at  any  margin  should  be  discarded  and  a  new  one  made. 
The  entire  inlay  may  now  be  disked,  always  running  the  disk  toward 
the  margin  of  the  cavity  and  never  away  from  it.  In  this  way  the  gold 
is  flowed  toward  the  margin  and  a  more  perfect  adaptation  is  obtained. 
If  the  inlay  is  worth  using  the  margins  should  be  so  tight  that  they  are 
not  discernible  to  the  naked  eye.  If  so  the  adaptation  is  so  good  that 
with  the  sealing  virtue  of  the  cement  the  inlay  will  save  the  tooth  as 
long  as  the  patient  will  need  it,  as  far  as  any  infiltration  decay  is  con- 
cerned. 

Wheii  this  adaptation  is  secured  the  inlay  should  be  removed  aad  the 
tooth  made  ready  for  cementation.  (See  also  Chapter  V.)  The  ideal 
method  is  to  place  the  rubber  dam  and  dry  the  tooth  with  warm  air 
supplemented  by  a  bath  of  alcohol  or  chloroform.  But  most  operators 
and  patients  object  to  the  use  of  the  dam  for  so  short  an  operation,  and 
the  use  of  cotton  rolls  and  the  saliva  ejector  will  keep  the  cavity  dry 
sufficiently  long  to  enable  the  operator  to  dry  and  disinfect  the  cavity- 
and  place  the  inlay.  If  so  the  cement  slab  with  the  proper  portions 
of  cement  should  be  on  the  bracket  ready  for  use,  the  cavity  should  be 
washed  out  with  a  strong  dash  of  warm  water  from  a  good  water  syringe 
and  the  cotton  rolls  immediately  placed  in  position.  The  tooth  should 
be  dried  and  washed  out  with  alcohol  or  chloroform,  again  thoroughly 
dried  with  the  hot-air  syringe  and  the  cement  mixed  to  a  creamy  con- 
sistency. By  a  creamy  consistency  is  meant  a  mix  that  will  drop  off  of 
the  spatula  rather  easily  and  yet  will  follow  the  instrument  for  some 
little  distance  as  it  is  lifted  in  the  air.  If  the  mix  is  too  thick  the  inlay 
will  not  go  into  place,  and  if  too  thin  the  cement  will  not  have  sufficient 
body  to  make  a  good  cementation  medium.  The  cavity  should  be  filled 
with  cement,  care  being  used  to  see  that  all  of  the  margins  of  the  same 
are  covered.  Many  failures  have  been  noted  on  account  of  not 
perfectly  filling  the  cavity  with  cement,  thereby  making  a  discrepancy 
between  the  inlay  and  tooth  at  some  point,  which  later  on  will  start 
an  infiltration  decay.  If  the  inlay  is  well  made  this  is  about  the  oiily 
possibility  for  infiltration  decay,  for  if  the  cement  has  been  well  adapted 
and  protected  by  the  inlay  there  is  no  possibility  of  a  percolation  of  the 
fluids  of  the  mouth  between  the  inlay  and  dentin.  If  there  is  to  be  any 
further  burnishing  it  must  be  done  while  the  cement  is  soft  and  before 
it  begins  to  crystalize,  but  there  should  be  no  necessity  for  burnishing 
at  this  time;  the  burnishing  that  might  have  been  necessary  should 
have  been  done  when  the  inlay  was  tried  in  the  cavity.  After  the 
cement  has  set,  either  at  this  time  or  at  some  future  engagement,  the 
inlay  may  be  polished  with  sandpaper  disks,  rubber  and  pumice. 
The  amount  of  polish  that  may  be  given  is  at  the  discretion  of  the 
operator,  but  better  results  are  obtained  by  a  finish  that  is  not  too  high, 


INDIRECT  METHOD  OF  MAKING  GOLD  INLAYS  283 

for  too  great  a  polish  will  so  reflect  the  light  that  the  gold  will  look 
black  in  some  lights.  Be  sure  that  there  is  no  cement  under  the  free 
margin  of  the  gums  or  between  the  teeth,  wash  out  all  cement  particles 
and  dismiss  the  patient. 

INDIRECT  METHOD  OF  MAKING  GOLD  INLAYS. 

The  reader  is  referred  to  Chapter  VI   for  a  description  of  this 
process. 


CHAPTER  V. 
GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS. 
By  MARCUS  L.  WARD,  D.D.Sc. 

This  chapter  is  written  as  a  short  supplement  to  Chapter  IV,  in 
order  to  fill  what  appeared  to  some  of  my  colleagues  a  void  in  the 
presentation  of  modern  operative  dentistry. 

During  very  recent  years,  with  the  development  of  better  technic 
for  the  construction  of  cast  gold  inlays,  there  has  been  a  quite  general 
use  of  the  gold  inlay  as  a  bridge  attachment  which  has  brought  a  new 
branch  of  work  from  the  field  of  bridge-work  into  operative  dentistry. 
With  the  rapid  recognition  of  the  many  advantages  of  the  inlay  form 
of  attachment  for  bridge-work  it  appears  likely  there  will  be  an  even 
more  general  use  of  the  gold  inlay,  thereby  bringing  the  subjects  of 
crown  and  bridge-work,  and  what  has  formerly  been  designated  as 
operative  dentistry,  into  such  close  relationship  that  it  will  be  difficult 
to  distinguish  one  from  the  other.  It  is  this  probability  that  makes 
the  presentation  of  the  subject  of  gold  inlays  appear  incomplete 
without  some  reference  to  their  use  as  bridge  attachments.  It  does 
not  seem  advisable  to  enter  into  a  discussion  of  the  subject  of  bridge- 
work  in  this  chapter,  for  that  would  involve  a  discussion  of  many 
problems  that  are  at  the  present  time  properly  assigned  to  books  on 
bridge- work.  It  is  rather  to  enlarge  upon  the  statements  made  by  the 
authors  of  Chapter  IV  with  respect  to  the  advantages  of  the  gold  inlay 
than  to  enter  into  a  discussion  of  the  subject  of  bridge-work.  This  is 
particularly  true  regarding  the  amount  of  stress  that  a  gold  inlay  will 
resist  without  dislodgment. 

It  has  been  pointed  out  in  Chapter  IV  that  all  fillings,  gold  inlays 
included,  should  have  as  nearly  parallel  walls  as  possible,  and  flat 
seatings  in  order  to  best  resist  the  stress  of  mastication.  This  is 
unquestionably  the  most  rational  practice  to  pursue  with  every  form  of 
filling  except  possibly  the  gold  inlay.  Inasmuch  as  many  operators 
have  found  it  more  advantageous  to  deviate  from  this  form  of  cavity 
preparation  in  some  cases,  there  has  developed  a  group  of  operators 
who  believe  that  the  cavity  for  the  gold  inlay  does  not  necessarily  need 
parallel  walls  for  retention.  Not  only  do  they  believe  that  parallel 
walls  are  not  always  necessary  for  the  single  inlay,  but  they  believe 
( 284 ) 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


285 


that  quite  extensive  fixed  bridges  may  be  attached  to  them  without 
dislodgment,  provided  certain  precautions  have  been  taken  to  resist 
stress  from  certain  directions.  There  is  practically  a  unanimity  of 
opinion  on  the  technic  of  construction  of  the  gold  inlay,  except  the 
necessity  for  parallel  walls,  and  the  reader  is  referred  to  Chapter  IV 


Fig.  235 

for  this  discussion.  This  chapter,  therefore,  will  be  devoted  to  a  brief 
consideration  of  tapered  walled  cavities  for  gold  inlays  and  their  use 
in  the  construction  of  inlay  attachments  for  bridge-work. 

Fig.  236  shows  a  tooth  and  cavity  which  represent  approximately 
the  form  of  cavity  preparation  that  the  author  used  for  gold  inlays 
during  the  years  just  preceding  and  those  immediately  following  the 


Fig.  236 


introduction  of  the  cast  gold  inlay  in  1907.  The  length  of  the  bevel 
shown  at  B  was  varied,  as  necessity  seemed  to  demand  in  order  that  the 
requirements  of  acceptable  cavity  formation  might  be  met.  Bucco- 
lingual  extensions,  as  well  as  cervical  extensions,  were  also  varied  wdth 
the  susceptibility  or  immunity  of  the  case  in  hand.     Likewise  the  depth 


286 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


of  the  occlusal  portion  of  the  cavity  was  varied  with  the  stress  likely 
to  be  applied,  especially  at  the  proximo-occlusal  margin. 

In  October,  1908,  on  assuming  charge  of  the  inlay  clinics  at  the 
University,  an  investigation  was  made  with  a  view  of  improving 
the  technic  of  making  cast  gold  inlays  which  were  receiving  general 
attention.  Many  of  the  casts  made  at  that  time  did  not  fit,  some  for 
one  reason  and  some  for  another.  Oftentimes  it  seemed  impossible  to 
get  certain  casts  near  to  an  acceptable  fit  of  the  cavity  notwithstanding 
that  much  effort  had  been  made  to  obtain  one.  It  was  noted  that 
mesio-occluso-distal  cavities  were  the  most  difficult  to  manage,  the 
greatest  defect  appearing  at  the  cervical  portion  of  the  inlay.  Many 
other  operators  made  the  same  observation.  One  large  dental  society 
had  one  of  the  profession's  distinguished  men  give  a  clinic  a  second 
time  to  show  how  to  remedy  the  defect  observed  by  the  use  of  crystal 
gold.    The  defect  observed  at  the  cervical  portion  of  the  casting  was 


Fig.  237 


large  enough  so  that  an  explorer  could  be  passed  between  the  casting 
and  the  cervical  wall  of  the  cavity,  and  could  be  seen  with  the  naked 
eye  in  ordinary  light.  Many  dentists  and  a  few  investigators  attrib- 
uted this  defect  to  the  shrinkage  of  the  gold.  Others,  however,  knew 
that  the  shrinkage  of  gold  on  a  piece  of  the  size  of  an  M  O  D  inlay  in  a 
molar  could  not  be  seen  with  the  naked  eye  as  readily  as  the  observed 
defect  could,  and  proceeded  to  investigate  other  parts  of  the  technic 
with  the  thought  in  mind  that  perhaps  the  form  of  the  cavity  was  a 
factor  of  importance.  The  author  was  one  of  the  latter  and  had  made 
some  hard  metal  molar  teeth  with  cavities  in  them  on  the  same  plan 
as  those  shown  in  Figs.  235,  236  and  237  and  several  forms  from  which 
wax  patterns  could  be  made.  The  hardness  of  the  metal  teeth  and  the 
metal  forms  made  bright  spots  on  the  castings  at  the  places  of  contact 
when  a  little  pressure  was  applied  to  the  castings.  In  the  MOD 
casting  the  bright  spot  occurred  first  at  points  A  and  B  (Fig.  237). 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS  287 

As  the  pressure  was  applied  to  the  occlusal  part  of  the  casting  it 
continued  to  bulge  out  at  the  cervical  part  C  and  D  until  there  was  a 
space  between  the  casting  and  cavity  that  would  allow  the  passage  of 
an  ordinary  explorer  with  ease.  At  this  time  it  was  observed  that  the 
casting  had  not  become  seated  at  the  occlusal  part  E,  which  led  to  the 
belief  that  the  shape  of  the  cavity  had  much  to  do  with  the  production 
of  the  defect  so  generally  observed  at  the  points  C  and  D,  for  the  casting 
had  been  brightened  by  the  metal  tooth  at  points  A  and  B  and  at  no 
others. 

Cavities  were  then  made  in  metal  forms  to  correspond  to  the  cavities 
shown  in  Figs.  235  and  236  from  which  castings  were  made.  Careful 
inspection  showed  no  particular  place  on  the  castings  made  for  the 
occlusal  cavity  (Fig.  235),  which  seemed  to  come  in  contact  with  the 
tooth  before  other  places  did.  They  seemed  to  go  to  place  without 
pressure  and  without  any  fitting.  The  castings  made  for  the  cavity 
shown  in  Fig.  236  almost  always  had  a  bright  place  on  them  at  A 
when  pressure  was  applied.  When  the  bright  spot  was  removed  by 
grinding  these  castings  would  go  to  place  without  force.  The  conclu- 
sion drawn  was  that  the  angle  formed  by  the  axial  and  occlusal  v/alls  of 
the  cavity  at  A  was  reproduced  in  the  investing  material  and  was  not 
strong  enough  to  resist  the  force  of  the  gold  when  it  was  thrown  into 
the  mold.  In  other  words,  it  appeared  that  there  had  been  a  slight 
compression  of  the  investing  material  at  the  point  A,  resulting  in  a 
little  too  much  gold  in  the  casting.  Work  was  then  taken  up  on  the 
MOD  cavity  (Fig.  237)  in  connection  with  the  M  O  cavity  (Fig.  236). 
In  both  cases  the  angles  A,  Fig.  236,  and  A  and5.  Fig.  237,  were  removed, 
making  a  distinctly  flat  surface  instead  of  an  approximate  right  angle. 
Castings  made  for  these  improved  cavities  showed  that  our  conclusions 
were  right.  There  had  been  a  compression  of  the  investing  material 
at  this  attenuated  point.  The  bright  line  did  not  appear  at  A,  Fig.  236, 
when  pressure  was  applied  and  these  castings  went  to  place  almost  as 
well  as  those  made  for  the  occlusal  cavity,  Fig.  235.  The  castings 
made  for  the  MOD  cavity  did  not  go  to  place  so  well  as  did  those  for 
the  occlusal  and  mesio-occlusal  cavities.  The  bright  line  that  had 
previously  appeared  at  A  and  B,  Fig.  237,  now  appeared  slightly  nearer 
to  the  cervical  portion  of  the  casting.  This  led  to  the  conclusion  that 
the  gold  had  shrunk,  and  that  shrinkage  prevented  placing  the  casting 
over  the  septum  of  dentin  between  the  mesial  and  distal  portions  of  the 
tooth.  This  presented  an  entirely  different  problem  than  was  presented 
in  the  compression  of  the  attenuated  part  of  investing  material.  In 
neither  the  mesio-occlusal  nor  the  occlusal  cavity  had  it  been  necessary 
to  construct  a  casting  that  would  go  over  the  septum  of  dentin  which 
separated  the  mesial  and  distal  portions.    As  we  ground  away  the 


288 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


mesial  and  distal  axial  walls  of  the  cavity  at  A  and  B,  and  toward  the 
cervical,  these  castings  did  not  bulge  out  at  C  and  D  as  before.  From 
this  it  appeared  that  a  problem  in  cavity  preparation  was  presented  in 
the  MOD  cavity  that  did  not  exist  in  any  others.  It  was  evident 
that  a  casting  which  had  shortened  in  a  mesio-distal  direction  in  the 
slightest  degree  would  not  go  to  place  until  ?t  had  been  stretched.     This 


Fig.  238 


deduction  led  to  the  adoption  of  tapered  axial  walls  and  the  production 
of  other  metal  teeth  (Figs.  238,  239  and  240),  with  one  incline  from  the 
seat  of  the  cavity  to  the  margins  instead  of  the  two  inclines  that  we  had 
used  previously,  and  which  are  shown  in  Figs.  235,  236  and  237.  This 
was  done  on  the  basis  of  first  being  able  to  get  a  wax  pattern  that  was 
more  accurate,  and  second,  and  equally  important,  to  stretch  the  gold 


Fig.  239 


Fig.  240 


better  with  a  cone-shaped  septum  of  dentin  than  with  a  septum  which 
had  parallel  walls.  The  results  with  this  form  of  cavity  were  very 
gratifying.  The  castings  before  they  were  fitted  did  not  go  to  place. 
With  the  gradual  taper  that  was  given  to  the  axial  walls,  however, 
only  a  little  pressure  was  necessary  to  force  castings  of  pure  gold  to 
place.     In  fact,  these  castings  were  forced  to  place  so  easily  that  one 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


289 


was  hardly  conscious  of  having  exerted  any  pressure.  When  other 
materials  were  used  for  these  castings  much  more  difficulty  was 
encountered  in  fitting  excellent  castings.  Such  materials  as  dark  22 
carat  gold,  clasp  metal,  etc.,  required  repeated  annealings  and  an  equal 
number  of  applications  of  pressure  in  order  to  get  them  to  fit  as  accu- 
rately as  the  pure  gold  ones  did  with  little  pressure. 

The  fact  that  the  alloys  of  gold  did  not  go  to  place  as  easily  as  the 
pure  gold  castings  led  many  to  believe  that  greater  shrinkage  had 
taken  place  when  the  former  rather  than  the  latter  were  used.  While 
it  is  possible  that  future  research  may  demonstrate  a  greater  coefficient 
of  volume  change  for  the  alloys  of  gold  than  for  pure  gold,  it  has  not 
been  done,  and,  as  a  result,  we  are  left  with  only  one  explanation  for 


. 


1     J" 


Fig.  241 


Fig.  242 


Fig.  243 


the  greater  ease  with  which  the  pure  gold  castings  are  fitted,  namely, 
they  stretch  easily.  The  ease  with  which  pure  gold  may  be  stretched 
may  be  shown  by  the  use  of  a  hardened  steel  cone  such  as  is  shown  in 
Figs.  241  to  244  inclusive.  Fig.  241  shows  a  receptacle  for  the  forma- 
tion of  a  wax  washer  and  a  paralleling  device  for  the  removal  of  the  wax 
without  distorting  it.  Fig.  242  shows  the  device  partially  opened  with 
the  wax  lifted  from  its  seat  and  not  touching  the  steel  cone.  Fig.  243 
shows  the  device  with  the  wax  trimmer  placed  over  the  cone  for  the 
purpose  of  making  the  wax  washer  perfectly  flat  on  the  top  and  of  the 
same  thickness  all  around.  The  steel  cone  is  three  inches  high  and 
0.03  of  an  inch  smaller  at  the  top  than  the  bottom  which  is  0.250  of  an 
inch,  and  is  as  nearly  a  perfect  taper  as  can  be  made.  Fig.  244  shows  a 
19 


290 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


set  of  six  steel  cones  with  tapers  of  1,  5,  10,  15,  20  and  25  per  cent,  per 
inch  taper.  The  longest  of  the  six  cones  is  three  inches  high  and  is 
exactly  like  the  one  shown  in  Fig.  241.  This  makes  it  possible  to  remove 
a  wax  washer  from  the  wax  former  and  from  it  make  a  gold  washer, 
which  may  be  used  either  on  the  cone,  on  the  wax  former  or  on  the  set 
of  cones  with  their  different  tapers.  If  such  a  gold  washer  be  made 
under  the  best  technic  known  at  present  it  will  not  go  to  the  bottom  of 
the  steel  cone  from  which  the  wax  washer  came.  It  will  go  to  about 
the  place  shown  on  the  cone  at  the  left  end  of  Fig.  244.  If  it  be  cast 
from  pure  gold,  slight  pressure  will  carry  it  farther  down  on  the  cone. 
Thorough  annealing  and  another  application  of  pressure  will  carry  it 
nearer  to  the  base  of  the  cone.  A  repetition  of  the  process  of  annealing 
and  application  of  pressure  will  carry  it  still  farther  down.  If,  on  the 
other  hand,  the  washer  be  made  from  dark  22  carat  gold,  coin  gold 
or  clasp  metal  it  will  be  found  very  difficult  to  get  the  washer  down  by 


Fig.  244 


repeated  annealings  and  applications  of  the  same  pressure  as  was  used 
on  the  pure  gold  washer.  In  fact,  it  will  require  a  mallet  to  make  much 
progress  with  a  washer  containing  as  much  gold  as  the  one  used,  which 
was  0.500  of  an  inch  in  diameter,  0.100  of  an  inch  in  thickness  and  had  a 
hole  in  the  center  0.250  of  an  inch  in  diameter.  If  a  washer  be  made 
from  the  same  material  that  contains  less  gold  it  will  be  just  that  much 
easier  to  carry  it  to  the  base  of  the  cone. 

If  a  perfectly  straight  rod  be  placed  in  the  wax  former  instead  of  the 
cone  with  its  1  per  cent,  per  inch  taper  and  a  pure  gold  washer  be  made, 
it  will  not  even  start  over  the  rod  on  account  of  shrinkage  of  the  gold. 
Any  attempt  to  force  it  will  result  in  an  upsetting  of  the  gold  at  the  edge 
of  the  hole  in  the  washer.  This  appears  to  be  exactly  what  takes  place 
when  MOD  cast  inlays  are  made  from  cavities  with  parallel  axial 
walls,  for  it  is  at  this  place  that  the  shrinkage  of  the  gold  first  interferes 
with  placing  the  casting.    Ffonj  this  it  seems  not  only  inipracticable, 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS  291 

but  impossible  to  construct  satisfactory  MOD  cast  gold  inlays  from 
patterns  made  from  cavities  with  parallel  axial  walls.  Some  claim 
that  they  can  do  it,  but  it  is  doubtful  if  their  observations  are  correct 
with  respect  to  the  walls  being  parallel,  for  it  does  not  seem  possible 
in  the  laboratory  where  accurate  measurements  can  be  taken.  In  the 
mouth  it  is  not  possible  to  tell  whether  the  walls  are  parallel  or  not. 
A  taper  of  1  per  cent,  per  inch  on  the  walls  of  most  cavities  is  not  visible 
to  the  naked  eye.  Indeed,  it  is  not  distinctly  visible  on  the  steel  cones 
until  the  cone  has  been  carried  to  a  height  of  about  three  inches.  With 
a  special  caliper  the  author  has  been  unable  to  be  certain  of  tapered 
axial  walls  until  about  5  per  cent,  per  inch  had  been  made  on  the  average 
cases  that  have  come  to  the  clinics.  (See  second  cone  from  left  end.) 
As  the  taper  reaches  25  per  cent,  per  inch  (see  cone  at  right  end)  it 
may  be  seen  readily  even  on  very  short  cones. 

With  the  set  of  cones  as  a  guide  and  the  special  caliper  the  author 
and  his  staff  have  made  a  careful  study  of  the  amount  of  taper  that 
could  be  used  not  only  on  the  axial  walls,  but  on  the  buccal  and  lingual 
portions  of  both  the  proximate  and  occlusal  parts  of  such  cavities  as 
shoTMi  in  Figs.  238,  239  and  240  as  well  as  their  modifications  due  to 
caries,  and  have  the  castings  resist  the  forces  of  occlusion  without 
dislodgment.  The  results  of  this  study  lead  us  to  believe  that  from  5 
per  cent,  per  inch  (see  second  cone  from  left  end)  to  20  per  cetit.  per 
inch  (see  second  cone  from  right  end)  is  permissible,  the  amount  used 
depending,  first  upon  the  length  of  the  castiag  from  the  cervical  to  the 
occlusal,  and  second,  upon  the  amount  of  stress  to  be  applied.  Short 
teeth  which  require  short  castings  from  cervijcal  to  occlusal  are  not 
suitable  for  bridge  attachments  in  the  work  of  mastication,  for  the 
amount  of  resistance  to  lateral  stress  is  not  sufficient  to  hold  an  ordinary 
fixed  bridge. 

In  fact,  it  seems  that  the  length  of  the  cavity  from  cervical  to  occlu  al 
is  one  of  the  most  essential  factors  to  be  considered,  and  upon  this  question 
alone  one  may  settle  the  question  of  advisability  of  using  an  inlay  attach- 
ment for  a  bridge.  It  seems  to  make  little  difference  whether  there  is 
a  taper  of  5  to  20  per  cent,  per  inch  provided  the  cavity  is  in  a  tooth 
that  is  long  from  the  cervical  to  the  occlusal.  On  the  other  hand,  if 
the  tooth  be  one  that  is  short  from  cervical  to  occlusal  there  can  be  no 
question  but  that  the  least  taper  consistent  with  the  removal  of  the 
wax  pattern  and  the  fitting  of  the  casting  the  better  will  be  the  reten- 
tion, though  success  cannot  even  then  be  expected  to  attend  the  use  of 
such  teeth  for  attachments  for  bridge- work  unless  the  pulp  be  removed 
and  a  dowel  inserted  into  the  pulp  chamber. 

These  deductions  have  led  many  to  a  deviation  from  the  accepted 
policy  of  paralleling  the  walls  of  cavities  for  the  reception  of  fillings. 


292  GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 

These  deviations  as  shown  in  Figs.  238,  239  and  240  are  hmited  to  the 
preparation  of  cavities  for  the  reception  of  cast  inlay  filHngs  and  bridge 
attachments  for  the  following  reasons : 

1.  Parallel  walls  cannot  be  detected  in  cavities  in  teeth  in  the  mouth. 
It  requires  upward  of  5  per  cent,  per  inch  on  short  axial  walls  in  order 
to  be  certain  that  there  are  no  undercuts. 

2.  Parallel  walls  will  not  permit  the  removal  of  an  accurate  wax 
pattern  from  the  cavity. 

3.  Tapered  walls  facilitate  the  fitting,  especially  in  M  O  D  castings. 

4.  Parallel  walls  are  not  necessary  for  the  retention  of  cast  gold 
inlays  either  as  fillings  or  bridge  attachments  except  in  teeth  which  are 
short  from  cervical  to  occlusal.  In  such  cases  it  is  a  question  whether 
the  judgment  of  the  profession  will  not  eventually  lead  us  to  consider 
such  cases  contra-indicated  for  bridge  attachments. 

5.  A  sharp  angle  in  any  part  of  a  cavity  such  as  is  shown  at  A, 
Fig.  236  or  A  B,  Fig.  237,  will  produce  an  attenuated  place  in  the. 
present  investing  materials  and  result  in  an  inaccurate  casting. 

A  study  similar  to  the  one  made  on  the  shapes  of  cavities  for  fillings 
has  been  made  on  castings  that  are  capable  of  retaining  fixed  bridges 
of  four  and  five  teeth,  for  example,  one  from  cuspid  to  first  or  second 
molar  or  from  cuspid  to  cuspid  either  in  maxilla  or  mandible.  Care- 
ful records  of  scores  of  cases  have  shown  that  the  MOD  cast  inlay  in 
molars  (Fig.  240)  or  bicuspids  that  have  their  pulps  in  them  and  have 
not  had  the  dentin  cut  away  between  the  mesial  and  distal  portions, 
and  are  of  the  average  length  from  cervical  to  occlusal,  will  hold  the 
average  fixed  bridge  of  the  length  mentioned,  provided  the  casting  has 
been  done  with  an  alloy  of  gold  that  is  as  strong  or  stronger  than  dark 
22  carat  gold.  It  should  be  obvious  that  a  molar  which  has  the  dentin 
cut  away  between  the  mesial  and  distal  portions  is  likely  to  fracture 
when  the  stress  of  a  bridge  involving  only  three  teeth  is  attached  to  it. 
A  bicuspid  being  a  smaller  tooth  has  even  less  dentin  on  the  buccal 
and  lingual  walls  if  a  channel  has  been  cut  through  the  dentin  con- 
necting the  buccal  and  lingual  walls  by  previous  filling  or  caries,  and 
is,  as  a  result,  less  desirable  than  a  molar  under  such  conditions  from 
the  standpoint  of  the  fracture  of  the  tooth.  Such  inlays  will  often 
become  dislodged  more  easily  than  those  made  from  teeth  which  have 
a  good  septum  of  dentin  between  the  buccal  and  lingual  walls. 

From  the  standpoint  of  liability  of  fracture  of  the  tooth  and  the 
greater  chance  of  dislodgment,  the  MOD  inlay  seems  contra-indicated 
in  cases  which  do  not  have  a  good,  strong  septum  of  dentin  between 
the  buccal  and  lingual  walls  in  either  teeth  with  pulps  in  them  or 
pulpless  teeth. 

Many  different  forms  of  partial  crowns  have  been  suggested  which 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


293 


would  protect  the  tooth  from  fracture,  but,  as  a  general  rule,  this  has 
been  done  without  having  first  given  special  attention  to  the  forces  which 
fracture  such  teeth.  Some  of  the  partial  crowns  that  have  been  suggested 
as  bridge  attachments  have  covered  entirely  too  much  of  the  tooth  and  the 
result  has  been  either  devitalized  or  irritated  pulps  within  a  year  or  two  after 
the  insertion  of  such  a  bridge.  The  adventitious  effect  of  large  masses  of 
metal  in  contact  with  tooth  tissue  has  been  studied  by  several  pathol- 
ogists, and  some  work  has  been  reported  which  seems  to  indicate  the 
use  of  the  least  amount  of  metal  in  contact  with  the  tooth  tissue  that 
is  consistent  with  strength.  It  is  necessary  that  the  inlay  or  partial 
crown  does  not  stretch  under  the  stress  of  mastication,  for  if  it  stretches 
even  a  slight  amount  it  is  usually  dislodged  soon  afterward.  The 
stretching  will  manifest  itself  by  a  pulling  away  from  the  remainder  of 
the  inlay  of  the  proximate  portion  of  the  inlay  that  is  soldered  to  the  re- 
mainder of  the  bridge.    This  may  be  prevented  by  making  the  occlusal 


Fig.  245 


Fig.  246 


portion  of  the  inlay  deeper  and  wider  and  by  extending  the  gold 
around  the  lingual  portion  of  the  tooth  as  shown  in  the  upper  molar 
(Fig.  245)  and  around  the  buccal  portion  of  the  lower  molar^  (Fig.  246) . 
These  castings  will  stretch  when  pressed  over  a  conical  piece  of  dentin 
but  will  not  stretch  under  the  stress  of  mastication  if  proper  precautions 
are  taken  to  get  the  proper  resistance  to  stress. 

Some  have  suggested  the  extension  of  the  gold  toward  the  cervical 
to  the  point  A,  Fig.  247,  and  a  similar  place,  Figs.  245,  246  and  249, 
but  it  seems  to  have  only  one  thing  in  its  favor,  namely,  it  furnishes 
a  little  more  surface  retention  for  the  cement  between  the  tooth  and 
inlay.  The  additional  amount  of  metal  that  this  extension  necessi- 
tates in  contact  with  the  tooth  at  a  vulnerable  point  appears  to  more 
than  counterbalance  any  other  thing  in  its  favor.    Up  to  the  present 


1  The  location  of  the  contact  points  on  the  lower  molars  and  bicuspids  usually  makes 
it  more  practicable  to  use  the  buccal  side. 


294 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


time  inlays  from  such  cavities  as  shown  in  Fig.  248  seem  to  be  much 
less  irritating  to  the  pulps  of  teeth  than  those  which  extend  near  to 
the  cervical  portion  of  the  teeth.  This  form  of  inlay  attachment  is 
simply  an  M  O  D  inlay  which  has  been  extended  over  to  the  buccal 
and  lingual  surfaces  sufficiently  far  to  prevent  fracture  of  the  tooth. 


Fig.  247 

It^may  be  seen  that  the  hold  which  this  attachment  has  on  the  tooth 
is  much  like  that  of  a  crown,  though  it  has  much  less  metal  in  contact 
with  the  tooth  than  the  crown  has.  This  attachment  has  been  very 
satisfactory  for  pulpless  teeth  and  for  teeth  with  pulps  in  them  which 
have  had  the  dentin  between  the  mesial  and  distal  portions  cut  away. 
In  fact  this  attachment  is  doing  all  that  any  gold  crown  has  done  in 


Fig.  248 


the  author's  hands  and  has  been  the  means  of  nearly  eliminating  the 
full  crown.  It  permits  the  retention  of  the  pulp  when  the  teeth  are 
vital,  and  in  all  cases  makes  it  unnecessary  to  employ  a  band,  thereby 
eliminating  one  of  the  most  frequent  sources  of  irritation  and  infection. 
Fig.  249  shows  tooth  and  an  attachment  for  upper  bicuspids  similar 


GOLD  INLAYS  AS  ISRtDGE  ATTACHMENTS 


295 


to  the  one  for  molars,  which  has  been  equally  satisfactory  though 
applicable  in  a  less  number  of  cases  on  account  of  the  greater  objection 
to  the  exposure  of  gold  to  view  as  the  teeth  are  located  anterior  to  the 
molars. 


f%\ 

/. 

>^ 

I            K"v>*" 

^J/\ 

\ 

/      If  i 

r-i 

Kill 

I  •^ 

^   \ 

1 

L- 

J| 

\ 

V          W^  • "  ~- 

■ 

Fig.  249 


Fig.  250 


Fig.  250  shows  a  lower  bicuspid,  an  M  O  D,  and  a  partial  crown  pre- 
paration.    It  is  seldom  that  the  MOD  inlay  is  indicated  in  the  lower 


296 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


bicuspids,  for  the  lingual  wall  is  usually  weak.  On  account  of  the  low 
lingual  cusp,  especially  on  the  first  bicuspid,  and  the  narrowness  from' 
mesial  to  distal  of  the  lingual  side  of  these  teeth,  the  preparation  shown 
in  Fig.  250  c,  is  preferable  in  nearly  all  cases.  The  location  of  the 
contacts  of  these  teeth  with  adjacent  teeth  makes  it  necessary,  as  a  rule, 


Fig.  251 

to  make  the  partial  crown  preparation  in  order  to  get  room  to  solder 
the  attachment  to  the  remainder  of  the  bridge. 

Figs.  251  and  252  show  MOD  inlays  for  cuspids  that  will  carry  one 
end  of  a  bridge  from  cuspid  to  the  first  or  second  molar.  They  are 
simply  MOD  inlays  that  have  either  one  22  gauge  iridio-platinum  pin 
set  each  side  of  the  horn  of  the  pulp,  Fig.  251,  or  a  groove  from  mesial 
to  distal  (A,  Fig.  252)  for  the  purpose  of  resisting  stress  from  the  labial. 


Fig.  252 


Some  have  suggested  preparations  for  the  cuspid  teeth  that  were  cut 
on  the  lingual  to  the  position  A,  Fig.  253.  Such  castings,  however, 
will  not  resist  labio-lingual  and  bucco-lingual  stresses  as  well  as  those 
made  from  the  cavities  shown  in  Figs.  251  and  252,  unless  a  groove  has 
been  cut  along  the  axial  wall  at  B,  Fig.  253.    Some  claim  they  are  able 


GOLD  INLAYS  AS  BRIDGE  ATTACHMENTS 


297 


to  do  this,  but  the  author  has  been  unsuccessful  in  his  attempts  to  teach 
students  to  cut  grooves  along  the  axial  walls  of  proximate  cavities 
except  in  the  teeth  of  middle  aged  and  old  people. 

The  development  of  the  attachment  shown  in  Figs.  251  and  252 
seems  to  meet  the  demands  of  both  young  and  old  people,  and  for  the 
present  the  grooving  of  all  axial  walls  has  been  abandoned. 


Fig.  253 

Figs.  254  and  255  show  preparations  that  have  been  successful  in 
central  incisors  that  are  very  similar  to  the  cuspid  preparations.  As 
in  the  cuspid  preparation  the  abseace  of  the  lingual  cusp  makes  it 
necessary  to  use  either  the  pins,  A,  Fig.  254,  or  groove,  A,  Fig.  255, 
to  prevent  force  from  the  labial  from  dislodging  the  attachment.     It 


Fig.  254 


Fig.  255 


should  be  remembered  that  cuspids,  incisors,  lower  bicuspids  and  often 
second  lower  bicuspids  do  not  have  the  same  resistance  to  forces  from 
the  labial  and  buccal  that  a  molar  or  upper  bicuspid  has,  and  when 
an  attachment  for  a  bridge  is  to  be  made  for  these  teeth  some  form  of 
resistance  to  these  stresses  must  be  made.  Three  ways  have  been 
suggested,  namely: 


298  COLD  INLAYS  AS  BRIDGE  ATTACHMmTS 

1.  Extension  of  the  metal  to  either  the  labial  or  buccal  or  lingual, 
or  both  walls. 

2.  Placing  small  pins  in  the  incisal  portion  of  the  tooth. 

3.  Cutting  a  groove  either  across  the  incisal  portion  of  the  tooth  or 
along  the  axial  walls,  the  latter  usually  applicable  to  teeth  of  persons 
who  are  middle  aged  or  older. 

It  may  be  noted  that  all  of  the  attachments  suggested  as  having  been 
successful  are  made  on  the  plan  of  tapered  walls.  Scores  of  these 
attachments  have  been  inserted  during  the  last  seven  or  eight  years 
under  all  kinds  of  conditions  except  in  short  teeth.  None,  in  recent 
years,  have  been  placed  in  teeth  which  were  short  from  cervical  to 
occlusal,  for  success  has  not  attended  this  kind  of  practice,  notwith- 
standing that  the  walls  of  such  cavities  have  been  made  as  nearly 
parallel  as  possible,  with  proper  protection  against  undercuts.  With 
the  exception  of  the  short  teeth,  therefore,  and  with  proper  attention 
to  the  precautions  pointed  out  with  respect  to  liability  to  fracture, 
stretching  of  the  inlay  at  the  occlusal  portion,  protection  against 
labial  and  buccal  stresses  on  teeth  without  lingual  cusps,  the  tapered 
walled  cast  inlay  attachment  may  be  regarded  one  of  the  most 
rational  methods  of  practice. 


CHAPTER  VI. 

HIGH  FUSING  PORCELAIN  INLAYS. 

By  W.  a.  capon,  D.D.S. 

PREPARATION  OF  CAVITIES. 

The  success  of  an  inlay  will  depend  largely  upon  four  points  of  differ- 
ence between  its  cavity  preparation  and  that  for  those  of  foil,  gutta- 
percha, amalgam,  or  cements,  viz.,  upright  walls,  square  enamel  edges, 
no  undercuts,  and  depth.  The  walls  being  perpendicular  or  nearly  so, 
allow  the  easy  withdrawal  of  the  metal  matrix  either  of  platinum  or 
gold,  or  in  the  case  of  the  impression  for  casting  with  wax  or  any  mate- 
rial for  the  purpose  of  making  a  model.  The  enamel  edges  are  made 
square  so  that  the  inlay  will  have  no  overhanging  frail  edges  of 
porcelain. 

An  undercut  will  prevent  the  easy  removal  of  the  matrix  frequently 
distorting  it,  and  when  using  wax  not  even  the  slightest  undercut  is 
permissible.  In  connection  with  porcelain,  depth  of  cavity  has  much 
to  do  with  retention,  in  fact  it  is  more  important  than  various  keys  and 
irregular  forms  advocated  by  many  writers  on  this  subject.  Unfor- 
tunately we  cannot  always  get  sufficient  depth,  and,  on  the  contrary, 
many  cavities,  when  entirely  cleared  of  decay,  are  too  deep  to  obtain 
an  unmutilated  matrix  particularly  with  platinum;  however,  when  this 
condition  exists,  it  is  an  easy  matter  to  reduce  it  by  partially  filling 
with  cement  or  gutta-percha. 

The  advantages  of  depth  are  retention,  strength,  through  quantity 
of  material,  and  purity  of  shade  by  having  sufficient  volume  of  porcelain 
which  assists  materially  in  reducing  the  opacity  caused  by  the  cement. 

This  rule  pertaining  to  deep  cavities  has  not  the  same  value  when 
applied  to  the  cast  gold  inlay,  and  it  is  well  to  note  that  the  same  rules 
which  apply  to  porcelain  inlays  are  applicable  to  matrix  gold  inlays, 
except  that  point  pertaining  to  shading,  because  cavities  prepared 
for  matrices  have  always  the  burnishing  feature  prominent,  which 
means  curves  and  all  surfaces  accessible  to  the  burnisher. 

The  formation  of  cavities  is  greatly  assisted  by  special  burs,  stones 
and  chisels  of  various  sizes  and  curves,  as  illustrated  in  Figs.  256  and 
257. 

(299) 


300 


HIGH  FUSING  PORCELAIN  INLAYS 


The  following  representations  of  various  cavities  in  natural  teeth 
where  porcelain  is  indicated  and  applicable  are  shown  with  the  same 
cavity  prepared  and  ready  for  the  matrix.  By  this  means  the  student 
will  readily  note  what  is  requisite  and  necessary  without  detailed 
description  and  technical  nomenclature. 


4  5  6  7  8  9  10  11 

Fig.  256. — Simpson's  automatic  chisels  (proximate). 


*2 


1      ■      ■ 


O  0 


D  D 


13 


Fig.  257. — ^Burs  and  stones. 


Simple  Cavities. — Figs.  258  to  265  show  simple  cavities,  and  in  each 
case  the  border  has  been  extended  beyond  the  outline  of  decay,  for  the 
same  consideration  with  respect  to  extension  is  applied  in  this  class  of 
work  as  if  the  cavity  were  to  be  filled  with  gold. 

Figs.  266  and  267  are  in  the  same  class  but  are  more  difficult,  for  they 
have  resulted  from  another  cause,  viz.,  abrasion  or  erosion,  and  it  is 
noted  particularly  because  this  condition  is  common,  and  the  cavity 
preparation  much  more  difficult.  The  depth  is  insufficient  and  the 
margins  are  never  defined,  which  necessitates  extensive  cutting  into 
hard  and  unusually  sensitive  dentin,  and  as  this  kind  of  cavity  is  almost 
as  common  in  lower  teeth,  the  difficulty  of  preparation  and  general 
manipulation  is  increased.    This  applies  to  all  labial  cavities  and  is 


PREPARATION  OF  CAVITIES 


301 


noticed  more  in  porcelain  operations,  because  when  the  cavity  is  ready 
the  matrix  must  be  held  in  position  firmly,  a  procedure  interfered  with 


Fig.  258 


Fig.  259 


Fig.  260 


Fig.  261 


Fig.  262 


Fig.  263 


by  the  lower  lip  and  the  saliva.  The  use  of  rubber  dam  is  not  desirable 
because  it  reduces  the  working  space,  but  it  has  other  advantages 
occasionally. 


302 


HIGH  FUSING  PORCELAIN  INLAYS 


Proximate  Cavities. — Figs.  268  to  277  show  cavities  presenting  greater 
difficulties  both  in  preparation  and  general  manipulation.  The  prep- 
aration of  cavities  in  such  positions  requires  ample  space  between  the 


Fig.  264 


Fig.  265 


Fig.  266 


Fig.  267 


adjoining  teeth,  otherwise  a  matrix  cannot  be  withdrawn  or  the  finished 
filling  inserted.  Sometimes  it  is  impossible  to  get  sufficient  space  for 
drawing  the  matrix  without  distortion;  in  such  instances  the  cavity  is 


PREPARATION  OF  CAVITIES  303 

prepared  with  this  point  as  a  first  consideration.    Fig.  277  shows  a 
cavity  of  this  kind.     If  there  is  not  much  difference  in  outHne  of  the 


Fig.  268  Fig.  269  Fig-  270 

cavity  labiallyor  Hngually,  choose  the  labial  side  from  which  to  remove 
the  matrix;  or,  if  cutting  the  labial  margins  does  not  interfere  with 
the  welfare  of  the  tooth,  resort  to  this  assistance  in  preference  to  diffi- 


FiG.  271  Fig.  272 

culties  of  lingual  matrix  removals.      In  Figs.  269  and  271  the  matrix 
under  ordinary  condition^  will  be  withdra,wn  lingually.    Figs.  270  ^nd 


304 


HIGH  FUSING  PORCELAIN  INLAYS 


272  show  uncertain  incisal  edges  which  are  reduced  in  Figs.  273  and  275; 
therefore  the  difficulties  of  drawing  a  matrix  in  this  case  are  very  much 


Fig.  273 


Fig.  274 


Fig.  275 


Fig.  276 


Fig.  277 


reduced,  for  the  cavity  is  so  large  that  working  space  is  greatly  ex- 
tended. Large  proximate  cavities  of  Fig.  272  type,  where  the  incisal 
edge  is  of  greater  strength  and  is  retained,  are  very  difficult  and  frequent. 


PREPARATION  OF  CAVITIES 


305 


The  matrix  formation  requires  skill  and  patience,  but  the  reward  is 
durability — for  the  inlay  in  this  case  is  thoroughly  protected  and  is 
rarely  unseated. 

Figs.  278  and  279  show  a  cavity  on  the  gingival  border  extending  under 
the  gum  margin  and  involving  a  considerable  portion  of  the  tooth 
mesially  and  distally.  It  is  a  typical  representation  of  this  form  of 
cavity  and  the  position  is  one  demanding  a  restoration  with  porcelain. 
The  cavity  walls  are  governed  by  its  extent,  for  the  matrix  will  warp 
if  a  strict  rule  of  upright  walls  is  carried  out  here.  The  cervical  wall 
will  not  be  at  right  angles  to  the  pulpal  wall  or  floor,  or  if  so  made  they 
cannot  be  of  that  form  at  the  extreme  mesial  and  distal  border;  there- 
fore, in  these  cavities  strict  adherence  to  a  right  angle  upright  wall  is 
not  possible  for  the  best  result.    When  the  matrix  is  burnished  it  should 


Fig.  278 


Fig.  279 


be  packed  with  gum  camphor  in  preference  to  other  materials  recom- 
mended. It  is  not  always  possible  to  make  a  very  extensive  inlay  of 
this  kind  of  one  piece,  therefore  it  should  be  divided  at  the  median  line 
of  the  tooth  and  two  operations  made. 

Proximo-incisal  Cavities. — Figs.  280  to  284  represent  extensive  proxi- 
mate cavities  or  fractures  extending  to  the  incisal  edge,  and  in  a  position 
where  porcelain  is  of  great  importance.  The  apparent  insufficient 
anchorage  deters  many  operators  from  using  porcelain,  and  the  prep- 
aration of  these  cavities  is  the  cause  of  more  different  opinions  than 
any  other.  It  is  claimed  that,  without  a  key  or  step  on  the  lingual 
surface,  porcelain  will  not  be  retained  by  the  ordinarily  prepared 
cavity,  and  unnecessary  cutting  of  good  tooth  structure  is  taught  with 
most  deplorable  results — in  many  instances,  irregularity  of  cavity  and 
its  borders  increase  the  matrix-formation  difficulties,  therefore  a  simple 
20 


306  HIGH  FUSING  PORCELAIN  INLAYS 

preparation  is  taken  advantage  of.     With  few  exceptions  the  cavity 
can  be  prepared  similarly  to  Fig.  280,  defining  the  labial  and  lingual 


Fig.  280  Fig.  281 

walls  and  anchorage  increased  by  a  groove  with  a  round  bur  at  the 
gingival  border  resembling  a  deep  undercut,   as  for  a  gold  filling. 


Fig.  282  Fig.  283  Fig.  284 

Anchorage  is  also  increased  by  grooving  between  the  enamel  plates  at 
the  incisai  edge.    The  matrix  must  be  burnished  to  these  surfaces, 


PREPARATION  OF  CAVITIES  307 

otherwise  the  value  of  the  preparation  is  lost.  The  labial  outline, 
Fig.  283,  can  be  varied  in  many  ways,  but  angles  are  to  be  avoided 
whenever  possible.  Very  often  the  corner  is  of  the  form  of  an 
irregular  triangle  tapering  to  a  wedge  point  at  the  cutting  edge.  The 
porcelain  at  that  point  is  very  frail  and  will  break,  leaving  an  irrepar- 
able notch.  To  avoid  this,  cut  an  axial  wall  as  in  Fig.  284,  and  thus 
make  a  body  of  porcelain,  giving  strength  at  a  weak  point.  This  same 
cavity  is  sometimes  so  extensive  that  anchorage  is  made  by  wire  pins 
or  staples.  In  instances  where  the  incisal  section  of  the  tooth  has 
been  lost  by  accident  or  decay,  this  process  of  retention  is  preferable 
and  highly  recommended  for  permanency. 


Fig.  285 

Fig.  285  shows  a  central  tooth,  a  matrix,  and  the  porcelain  section  with 
wire  anchorage.  This  case  shows  loss  of  one-fourth  of  the  tooth  and 
the  cavity  made  by  cutting  the  dentin  to  the  required  depth,  an  opera- 
tion possible  with  few  exceptions.  The  enamel  edges  are  made  true 
by  a  fiat  stone,  after  which  the  matrix  is  made  of  the  walls  and  edges, 
and  shown  without  a  floor.  The  wire  is  iridio-platinum,  gauge  24, 
made  in  the  form  of  a  staple  or  loop,  and  inserted  while  the  matrix 
is  in  place;  with  these  in  position,  porcelain  in  paste  form  is  pressed 
over  all  and  excess  moisture  is  absorbed  by  holding  a  napkin  or  bibu- 
lous paper  to  its  surface.  The  combination  is  carefully  taken  from  the 
cavity  and  fused,  thus  forming  a  base  with  a  wire  loop  or  pins  held 
securely  without  soldering.  This  foundation  is  now  placed  on  the 
tooth  and  matrix  edges  thoroughly  burnished,  after  which  the  opera- 
tion is  completed  by  repeated  fusing.  When  the  matrix  is  removed, 
the  contoured  tip  will  resemble  the  third  section  of  Fig.  286,  and  is  ready 
for  cementing.  When  the  first  porcelain  is  applied  it  will  likely  fill  the 
loop,  but  this  must  not  be  corrected  until  after  fusing,  when  the  porce- 
lain is  easily  broken  away  with  blunt  pliers.  Frequently  the  staple  or 
loop  is  inverted  to  suit  conditions,  but  the  form  represented  is  the 
most  durable  in  every  particular.  The  difficulties  of  this  operation 
are  increased  by  the  irregular  form  of  fracture,  for  usually  they  extend 
lingually  and  frequently  quite  to  the  gum  margin;  a  restoration  of 


308 


HIGH  FUSING  PORCELAIN  INLAYS 


this  kind  should  not  be  attempted  until  the  operator  has  had  con- 
siderable practice,  for  the  making  of  an  incisal  tip  acceptably  is  one 
of  the  most  difficult  operations. 


Fig.  286 


Fig.  287 


Fig.  288 


Fig.  290 


Fig.  291 


Fig.  292  Fig.  293  Fig.  294  Fig.  295  Fig.  296 

Figs.  286  to  296  show  the  staples  in  various  applications,  including  corner  restorations. 

Bicuspid  and  Molar  Cavities. — Figs.  297  to  306  show  cavities  in  bicus- 
pids and  molars  for  porcelain  inlays.  The  forms  are  very  similar  and 
directions  for  cavity  technique  are  applicable  in  either  instance.  The 
value  of  porcelain  in  these  positions  is  questioned  because  the  force  of 


Fig.  297 


Fig.  298 


Fig.   299 


contact  is  increased  and  the  esthetic  value  is  decreased.  There  are 
many  exceptions,  and  the  opportunities  exist  in  mesial  surfaces  of 
superior  biscupids  and  molars.  The  occlusion  is  the  first  consideration, 
size  and  depth  of  cavity  are  next,  although  the  latter  is  generally 


PREPARATION  OF  CAVITIES 


309 


regulated  by  a  step  as  shown  in  the  sketches.     This  step  is  made  of 
cement  or  gutta-percha  and  not  of  the  same  extent  as  if  preparing  for 


Fig.  300 


Fig.  301 


a  gold  inlay.  The  gingival  borders  are  more  curved  and  the  step  is 
rounded  and  allowance  made  for  greater  thickness  of  porcelain  at  the 
occlusal  surface.     The  inlay  will  be  more  secure  without  a  step  or 


Fig.  302 


Fig.  303 


interior  preparation  of  any  other  material,  but  bicuspid  and  molar 
cavities  are  usually  too  deep  for  successful  matrix  formation.     If 


310 


HIGH  FVBING  PORCELAIN  INLAYS 


this  can  be  accomplished,  there  still  remains  the  difficulty  of  placing 
the  inlay,  because  of  greater  bulk  than  it  is  possible  to  get  space  for; 
however,  there  can  be  no  set  rule,  circumstances  and  good  judgment 


Fig.  304 


Fig.  305 


must  be  factors  at  all  times.  In  any  case  the  cavity  must  not  extend 
into  the  sulci  between  cusps  unless  the  sulci  are  of  sufficient  size  to 
assure  strength  of  porcelain.  Figs.  302,  304  and  306  show  enamel  sur- 
face edges  without  any  extension  to  the  sulci. 


F 

^ 

1 

■ 

1 

^.«#*" 

Hre"  ■ 

1 

^H 

p^'^l^l 

K: 

rl 

^^^K -n 

B 

1 

Fig.  306 


The  following  illustrations  represent  what  may  be  termed  unusual 
cavities  both  in  form  and  extent  for  porcelain  inlays. 


PkEPARAfiON  OF  CAVlfiM 


311 


Fig.  307  incisal  edge,  requiring  very  accurate  adaptation  because  of 
small  opportunity  of  retention.  If  the  mesial  and  distal  walls  are  not 
too  thin  on  the  incisal  enamel,  a  groove  in  the  cavity  will  assist,  but 
the  general  form  of  the  tooth  will  govern  this  suggestion. 

Fig.  308  an  unusually  large  form  of  labial  cavity  extending  to  the 
extreme  mesial  and  distal  borders  and  leaving  only  the  lingual  enamel 
plate. 

Fig.  309  a  labial  cavity  toward  the  incisal  edge  more  frequently 
seen  at  the  gingival  border. 


Fig.  307 


Fig.  308 


Fig.  309 


Fig.  310  represents  a  tj^e  of  preparation  for  a  porcelain  tip,  the 
original  enamel  being  defective  in  form  and  color. 

Fig.  311  a  mesial  cavity  extending  from  the  gingival  border  to  the 
incisal  edge  of  a  central.  Cavity  converging  extensively  labially  and 
the  lingual  cutting  edge  shortened  because  of  decay  and  weak  enamel. 


Fig.  310 


Fig.    311 


Fig.  312  linguo-mesial  cavity  extending  to  incisal  edge.  Lingual  wall 
reduced  because  of  weakness  of  enamel,  but  that  loss  is  added  strength 
to  the  porcelain  inlay. 

Fig.  313  an  extensive  labial  cavity  involving  the  whole  mesial  surface 
and  extending  lingually.  In  preparing  this  cavity  the  pulpal  wall 
angles  must  not  be  so  acute  that  the  matrix  cannot  be  withdra-wn  from 
the  incisal  section  between  the  enamel  plates  or  reducing  the  axial 
wall  at  the  incisal  edge  to  a  plaia  surface  may  be  necessary  to  prevent 
distortion  of  the  metal. 


312 


BIGH  FUSING  PORCELAIN  INLAYS 


Fig.  314  incisal,  labial  and  lingual  preparation  with  angles  to  assist 
retention. 

Fig.  315  lingual  preparation  for  mesio-incisal  restoration,  more  appli- 
cable to  gold  inlays.    This  form  of  retention  for  porcelain  is  not  gener- 


FiG.  312 


Fig.  313 


ally  recommended  because  of  increased  difficulty  in  obtaining  a  matrix 
from  the  under  surface  and  the  doubtful  assistance  of  a  substance  of 
such  friable  composition. 


Fig.  314 


Fig.  315 


PORCELAIN  RESTORATION  FOR  CHILDREN'S  TEETH. 

One  of  the  most  difficult  operations  for  any  dentist  is  the  restoration 
of  a  broken  permanent  incisor  of  a  child  between  the  ages  of  seven  and 
twelve  years.  The  tooth  is  generally  broken  by  an  accident  and  fre- 
quently the  pulp  is  not  affected,  but  the  tooth  is  extremely  sensitive. 
If  the  pulp  is  exposed,  devitalization  is  the  only  resort,  and  the  restora- 
tion can  be  made  with  porcelain,  using  an  iridio-platinum  pin  extending 
into  the  canal,  or  a  wire  loop  of  the  same  metal.  No.  24,  anchored  in 
the  remaining  part  of  the  crown. 

This  work  is  comparatively  easy,  because  the  main  requisite  for 
strength  is  anchorage,  which  is  possible  under  these  conditions.  When 
the  pulp  is  alive  and  apparently  healthy  it  is  generally  desired  that  such 
a  condition  be  preserved,  which  is  not  an  easy  matter  under  these 


PORCELAIN  RESTORATION  FOR  CHILDREN'S  TEETH 


313 


circumstances.  Something  must  be  applied  for  protection,  and  there- 
fore cement  is  used  because  of  its  tenacity.  No  mechanical  anchorage 
is  possible.  The  child  is  young  and  the  teeth  are  undeveloped,  there- 
fore they  must  be  kept  comfortable,  if  not  presentable,  for  some  years, 
for  it  is  my  experience  that  a  case  of  this  kind  at  the  age  mentioned 
is  irresponsible  and  the  dentist  must  bear  the  burden,  which  means  con- 
tinual replacement  and  general  botheration.  I  recommend,  therefore, 
that  nothing  permanent  be  attempted  until  the  case  has  arrived  at  an 
age  of  maturity,  when  the  patient  is  willing  to  use  care  with  what  has 
been  done  and  has  arrived  at  the  age  when  personal  appearance  has 
some  value. 

A  girl  patient  will  be  ready  for  a  permanent  operation  about  two 
years  before  a  boy.  Therefore,  it  is  fairly  safe  to  consider  a  finished 
operation  at  the  age  of  thirteen  to  fifteen  years.  In  the  meantime, 
during  the  intervening  years,  fracture  surfaces  must  be  covered  in  some 
agreeable  manner,  and  to  that  end  I  present  the  following  plan  of 
making  a  presentable  restoration. 


Fig.  316 


Fig.  317 


Fig.  316  represents  the  case  of  a  boy,  aged  eight  years,  left  central 
broken  by  a  fall,  pulp  not  exposed,  but  too  sensitive  to  allow  any  instru- 
mentation whatever.  I  kept  the  surface  covered  with  cement  for  one 
year,  which  demonstrated  the  fact  that  the  pulp  was  not  materially 
affected  by  the  fracture.  The  parents  insisted  that  something  more 
presentable  be  done,  so  an  accurate  impression  of  the  broken  section 
was  taken  in  plaster,  and,  after  drying,  a  model  was  made  of  Mellotte's 
metal.  Platinum  foil  No.  38  was  swaged  to  fit  the  broken  surface, 
extending  lingually  to  the  gum  line  and  labially  one  millimeter. 

This  formed  an  accurate  shell,  which  covered  the  tooth  except  on 
the  labial  and  proximate  surfaces.  This  thin  platinum  form  was  then 
reinforced  by  25  per  cent,  platinum  solder  and  a  small  staple  attached 
to  the  broken  surface  (Fig.  317)  for  the  purpose  of  holding  the  porcelain. 
After  three  fusings  the  restoration  was  completed  as  shown  in  Fig.  318. 
The  small  line  of  platinum  on  a  labial  surface  did  not  detract  from  the 
finished  operation  to  any  objectionable  extent  because  the  porcelain 


314 


til  Gil  FUSING  PORCELAIN  INLAYS 


corner  was  so  much  greater  in  size;  however,  the  improvement  quite 
paid  for  the  trouble. 

Wire  used  for  the  staple  was  iridio-platinum  No.  24.  The  surface 
of  porcelain  contact  was  etched  to  give  every  opportunity  of  attach- 
ment. This  case  was  in  use  for  five  years  and  had  the  advantage  of 
easy  replacement  of  either  the  whole  shell  or  repair  of  porcelain  if 
necessary.  If  gold  is  preferred,  the  metal  can  be  cast  direct  to  the 
foundation,  which  should  be  made  of  gold  instead  of  platinum. 


Fig.  318 


FORMATION  OF  THE  MATRIX  FOR  PORCELAIN. 

The  difficulties  pertaining  to  the  making  of  a  matrix  are  much 
reduced  by  having  plenty  of  space  between  the  teeth,  and  this  must  be 
obtained  prior  to  the  operation  by  means  of  tape,  cotton,  or  rubber 
wedges.  Mechanical  appliances  may  be  used  as  an  assistant  when  the 
inlay  is  made  and  the  space  for  easy  insertion  is  insufficient,  but  holding 
the  teeth  apart  while  making  the  matrix  is  usually  an  interference  that 
can  be  avoided  by  giving  this  part  of  the  work  proper  consideration. 
Room  to  work  is  a  good  rule  to  follow  in  any  operation,  but  it  is  posi- 
tively necessary  with  the  inlay,  because  the  mass  is  hard  and  unyield- 
ing with  breakable  edges.  It  must  be  placed  while  the  cement  is  soft, 
and  without  delay,  and  the  slightest  interference  may  mean  much  loss 
of  time  and  poor  results. 

A  gold  inlay  can  be  forced  to  place  without  damage,  but  an 
unpleasant  experience  or  two  with  porcelain  will  demonstrate  the 
desirability  of  having  plenty  of  space. 

The  reproduction  of  the  form  of  a  cavity  in  foil  for  an  inlay  is  called 
the  matrix,  in  which  the  porcelain  is  moulded  by  heating  to  a  degree 
required  to  fuse  the  component  parts  of  the  material  to  a  vitrified  mass. 
The  metal  most  generally  used  is  pure  platinum  foil,  tto¥  of  an  inch 
in  thickness.  Gold  foil  No.  40  is  also  largely  used,  but  only  in  connec- 
tion w^ith  a  low  fusing  porcelain  which  fuses  at  a  temperature  of  300° 
to  500°  less  than  gold.  Platinum  has  the  advantage  in  the  fact  that  it 
cannot  be  affected  by  any  heat  required  to  fuse  the  highest  grade  porce- 
lain.   It  is  not  so  ductile,  nor  so  easily  moulded  to  form,  but  this  dis- 


PORMATiON  OF  THE  MAfRIX  FOR  PORCELAIN 


Sl5 


advantage  is  counterbalanced  by  its  stability,  which  allows  greater 
freedom  from  care  as  to  the  changing  of  its  form  while  filling  with 
porcelain. 

A  gold  matrix  is  invariably  invested  to  prevent  its  changing  form 
and  protect  it  from  overheat.  This  requires  time  and  care,  therefore 
platinum  is  more  desirable  from  many  points,  and  practice  will  assist 
greatly  toward  easy  manipulation.  There  has  been  much  discussion  in 
the  past  upon  the  proper  thickness,  but  it  is  now  generally  conceded 
that  ToV  0"  of  an  inch  will  suit  all  cases  better  than  any  degree  thinner 
or  thicker.  A  thinner  material  has  not  the  stretching  quality,  and 
an3i;hing  heavier  will  cause  a  thicker  cement  line. 


Fig.  319 


A  simple  cavity  on  the  labial  surface  of  a  central  will  serve  to  illus- 
trate the  mode  of  procedure,  which  is  the  cutting  of  a  square  section 
of  the  foil  sufficiently  large  to  extend  over  the  adjoining  teeth,  holding 
the  corners  in  the  manner  of  Fig.  319,  and  while  held  securely  by  the 
fingers,  press  the  foil  over  the  cavity  with  some  material  such  as  spunk, 
cotton,  small  chamois  disks,  or  a  soft  rubber  point  like  a  pencil  end,  and 
in  this  manner  the  cavity  will  be  outlined  on  the  foil  and  that  portion 
covering  the  cavity  concaved  so  there  can  be  no  mistake  as  to  what 
portion  is  to  be  burnished.  Then  use  ball-pointed  burnishers  of  various 
sizes,  such  as  amalgam  instrmnents  shown  in  Figs.  320  to322,and  gently 
rotate,  gradually  pushing  the  burnished  surface  to  the  cavity  walls  and 
floor,  using  care  not  to  break  the  margins.  The  metal  will  probably 
split  or  break  as  it  is  forced  to  place,  but  unless  extremely  ruptured,  it 
will  not  interfere  with  final  results.  When  the  interior  portion  is  fairly 
fitted,  packed  with  spunk,  cotton,  or  gum  camphor,  and  held  seciu-ely 
with  a  blunt  instrument,  a  flat,  blunt  instrument  should  be  used  to  get 
perfect  margins.  Then  the  packing  is  removed  (except  when  using 
camphor,  which  is  biunt  out),  the  matrix  released  with  very  fine 


316 


HIGH  FUSING  PORCELAIN  INLAYS 


pointed  pliers,  and  results  noted.     Three  desirable  sets  of  burnishing 
instruments  are  illustrated  in  Figs,  323,  324  and  325. 

If  satisfactory,  the  next  step  is  filling  the 
mold  with  porcelain. 

Platinum  foil  should  be  thoroughly  an- 
nealed in  the  furnace  muffle;  the  heat  re- 
quired to  improve  its  softness  is  at  least 
2200°  F.  The  foil  purchased  at  the  present 
time  is  usually  ready  for  making  the  matrix, 
having  already  been  thoroughly  softened  at 
a  very  high  temperature.  A  matrix  of 
complex  character  will  require  more  than 
usual  burnishing,  which  will  have  a  ten- 
dency to  make  the  metal  harsh.  It  can 
then  be  re-annealed  to  advantage,  provided 
the  temperature  is  not  less  than  the  degree 
already  mentioned. 

An  excess  of  material  is  recommended  in 
labial  cavities  for  the  purpose  of  holding 
securely,  but  in  other  places  the  reverse 
..i  i^  ^1  is  desired;  notably  on  proximate  surfaces, 
where  the  excess  will  interfere  with  removal 
after  taking  the  form  of  the  tooth.  Bur- 
nishing the  matrix  in  proximate  cavities, 
corners,  and  tips  is  greatly  assisted  by 
strips  of  either  cotton,  rubber  dam,  or  gold- 
beater's skin  held  securely  over  the  metal, 
insuring  its  proper  position  and  preventing 
tearing  on  the  sharp  cavity  edges  (Fig.  326). 
Avoid  lapping  or  folding  of  matrix  on  cavity 
edges. 

After  the  matrix  is  made,  the  next  pro- 
cedure is  filling  it  with  porcelain.  This  is 
done  by  holding  the  mold  in  straight,  fine- 
pointed  pliers,  applying  the  porcelain  with 
a  fine  sable  pencil  brush,  or  the  end  of  a 
spatula  made  for  the  purpose  (Fig.  327). 
The  porcelain  powder  is  mixed  with  pure 
water,  distilled  preferably,  into  a  stiff  paste. 
Fig.  320    Fig.  321  Fig.  322  and  after  applying,  it  is  shaken  to  position 

either  by  tapping  or  drawing  the  serrated 
instrument  handle  across  the  pliers.  This  jarring  brings  the  moisture 
to  the    surface,  and  after  tracing  the  cavity  outline  and  removing 


FUSING  THE  INLAY 


317 


excess  with  brush,  it  is  laid  face  down  on  a  clean  towel,  bibulous  or 
blotting  paper,  which  absorbs  the  excessive   moisture.     The  inlay  is 


4  5        6  7         8         9  10 

Fig.  323. — Reeves  set  of  inlay  burnishers. 


then  dried  out  in  front  of  the  furnace  mufHe,  gradually  pushed 
into  the  furnace,  and  fused.  Too  rapid  drying  will  cause 
porcelain  to  jump  from  the  mold.  A  high  fusing  porcelain 
mixed  into  a  stiff  paste  will  shrink  about  one-fifth  its  bulk, 
therefore  a  second  or  third  fusing  is  required  before  the  inlay 
can  be  called  finished.  If  the  porcelain  is  thin,  its  proportion 
of  shrinkage  will  be  greater,  and  it  will  not  bridge  or  carry  its 
weight  across  any  tear  or  aperture  that  may  exist  in  the 
bottom  of  the  matrix;  and  in  deep  cavities  this  condition  is 
nearly  always  present;  therefore  it  is  necessary  to  always 
turn  the  matrix  wrong  side  up  and  carefully  note  its  condi- 
tion. Clean  ofi^  any  excess  with  the  brush  and  thus  avoid  a 
misfit,  for  it  is  impossible  to  remove  fused  porcelain  without 
distorting  the  matrix  or  totally  destroying  the  work  up  to 
this  point. 

FUSING  THE  INLAY. 

The  first  fusing  is  usually  called  "first  bake"  or  "biscuit," 
which  is  a  stage  wherein  the  component  parts  of  porcelain  are 
brought  together  by  the  heat  and  made  into  a  hard,  homo- 
geneous mass  without  gloss. 

It  is  at  this  stage  that  shrinkage  is  most  apparent,  and  it  is  a 
condition  that  exists  in  every  porcelain  operation  of  whatever 
dimensions.    Shrinkage  is  governed  by  quantity  and  quality  of  material 
and  is  a  prominent  factor  toward  success  or  failure.   In  small  inlays  shrink- 
age is  of  less  import,  but  in  proportion  to  size  it  must  be  dealt  with.     This 


318 


HIGH  FUSING  PORCELAIN  INLAYS 


shrinkage  may  be  sufficient  to  distort  the  matrix  or  cause  porcelain  to 
attach  to  the  matrix  walls.  As  it  is  never  consistent,  it  is  very  impor- 
tant to  control  it,  but  this  is  only  possible  to  a  small  extent.  Shrinkage 
toward  the  matrix  wall  is  most  desired  and  can  be  assisted  by  a  slight 
cut  or  groove  across  its  greatest  extent,  thereby  giving  the  porcelain 
an  impetus  in  that  direction.  In  large  spaces  much  assistance  in  con- 
trolling shrinkage  is  derived  from  using  small  particles  of  baked 
porcelain  mixed  with  the  unfused  paste. 


Fig.  324. — ^Weber's  glass  burnishers. 


After  the  first  fusing  of  the  inlay  the  excess  platinum  or  matrix 
material  should  be  trimmed,  leaving  a  working  margin  to  allow  a 
refitting  in  the  cavity.  In  small,  simple  cases  this  may  not  be  neces- 
sary, but  in  the  majority  of  cavities  it  will  assist  greatly.  If  the  matrix 
has  become  slightly  altered  by  shrinkage  or  careless  handling,  the  change 
is  noted  at  once  and  corrected.  In  contour  work  it  will  assist  the  eye 
to  determine  where  to  add  or  reduce;  in  fact,  there  can  be  only  very 
small  argument  against  a  trial  of  the  embryo  inlay  in  its  place  and 
reburnishing  the  cavity  edges. 


FUSING  THE  INLAY 


319 


Selecting  the  shade  is  the  first  requirement,  as  the  foundation  should 
approximate  the  final  shade,  but  after  the  inlay  is  reburnished,  this 


2  3  4  5  6 

Fig.   325. — Sausser's  matrix  burnishers. 


question  must  be  settled  in  the  operator's  mind,  and  the 
final  fusing  proceeded  with.  First,  clean  off  the  inlay  with  a 
brush  dipped  in  alcohol  or  warm  water,  thus  removing  saliva, 
blood  or  any  undesirable  particles,  then  carefully  fill  any  crevice 
caused  by  shrinkage  or  breakage,  finally  filling  the  matrix  or 
building  the  contour  or  section  as  desired,  always  considering 
shrinkage.  A  second  bake  may  be  sufficient,  but  usually  a 
third  is  required  or  even  a  fourth.  Frequent  firing  is  not 
harmful,  provided  the  porcelain  has  not  been  carried  to  a 
finishing  heat  previously.  Shrinkage  must  be  overcome, 
therefore  withdraw  the  work  from  the  furnace  before  it  is 
fused  and  note  its  condition. 

After  the  inlay  is  properly  fired  the  matrix  is  removed  by 
turning  the  metal  back  from  the  edge  with  pointed  pliers,  re- 
leasing the  inlay.  Frequently  small  particles  of  metal  adhere 
to  the  porcelain.  If  a  pointed  instrument  fails,  use  a  discarded 
bur,  but  in  larger  inlays  small  quantities  of  adhering  metal  will 
make  no  difference  in  any  way.  The  inlay  is  now  tried  in  place, 
having  the  cavity  wet,  which  helps  the  porcelain  to  blend  with 
the  natural  tooth,  and  at  this  stage  the  patient  should  be 
shown  the  results,  for  at  a  later  period  the  cement  and  dry- 
ing of  the  tooth  make  a  change  not  always  satisfactory,  but 
fortunately  this  is  largely  corrected  by  time. 

The  inlay  is  grooved  or  undercut  by  wheel  disks  such  as 
hard-rubber,  corundum,  or  copper  coated  with  diamond  dust. 
An  additional  retention  is  secured  by  using  hydrofluoric  acid. 
This  acid  has  a  great  affinity  for  all  vitrified  surfaces,  therefore 
great  care  is  necessary  that  the  outer  and  finished  surface  is  ^ 
thoroughly  protected,  and  the  most  simple  method  is  to  soften  the 
surface  of  a  small  piece  of  paraffin  or  beeswax,  and  embed  the  inlay  face 


320 


HIGH  FUSING  PORCELAIN  INLAYS 


downward .   Then  cover  the  exposed  surface  with  a  few  drops  of  the  hydro- 
fluoric acid,  and  after  about  five  minutes  wash  with  a  spray  of  water . 
The  use  of  acid  for  this  purpose  is  very  common,  and  the  tendency 
to  carelessness  is  sometimes  checked  by  a  bad  burn,  which  is  always 


Fig.  326 


painful  and  very  slow  to  heal.  After  the 
inlay  has  been  subjected  to  acid,  it  should 
be  soaked  in  alcohol,  which  will  soften  the 
white  scale,  which  is  removed  by  scraping 
the  surface  with  a  sharp  instrument,  and 
thereby  give  the  cement  a  better  attach- 
ment to  the  roughened  surface.  This  is  a  fjq  327 
point  not  generally  considered,  but  it  is 
reasonable  and  practicable,  and  many  small  inlays  have 
been  lost  through  non-observance  of  this  fact. 

As  the  inlay  is  now  ready  for  inserting,  the  tooth  is  dried 
and  protected  from  moisture  either  by  napkins  or  rubber 
dam.  The  latter  is  preferable,  but  not  necessary,  provided 
the  operator  can  use  a  napkin  properly.  Successful  inlays 
depend  upon  perfect  adaptation  and  cementation,  but 
frequently  the  operation  is  spoiled  through  carelessness 
or  a  desire  to  hurry  the  case  to  a  finish,  therefore  too  much 
stress  cannot  be  placed  on  this  important  part  of  the  work. 
The  cement,  the  shade  of  which  should  approximate  that 
of  the  tooth  and  inlay,  must  be  mixed  thoroughly,  be  of 
creamy  consistency  and  of  medium  to  slow  setting  quality. 
Apply  it  to  the  cavity  with  a  small  spatula  tip,  then 
gently  press  the  inlay  into  position,  wipe  off  excess  with 
spunk  or  tape,  and  note  the  line  of  demarcation.  If  this 
is  satisfactory,  hold  the  inlay  in  position  until  the  cement 
has  commenced  to  harden,  then  protect  from  moisture 
by  covering  with  melted  paraffin,  wax,  sandarac  varnish, 
or  chlora-percha.  If  the  inlay  is  extensive,  it  can  be  ligated 
with  floss  silk  or  held  by  a  wedge,  always  avoiding  the 
use  of  excessive  force,  or  the  delicate  porcelain  edges  will 
shatter. 


^ 


Fig.  328 


MAKING  INLAYS  BY  THE  INDIRECT  METHOD  321 

A  later  sitting  is  required  for  a  final  finishing,  for  the  best  of  inlays  will 
need  smoothing  of  edges,  which  is  done  with  small  stones  or  sandpaper 
disks  and  strips. 

MAKING  INLAYS  BY  THE  INDIRECT  METHOD. 

While  the  majority  of  porcelain  workers  are  satisfied  that  the  best 
results  are  to  be  obtained  by  working  directly  on  the  tooth  from  start 
to  finish,  it  is  claimed  by  others  that  results  equally  as  good  may  be 
had  by  swaging,  or  by  what  was  originally  known  as  the  water-bag 
process,  introduced  a  few  years  ago  by  a  London  manufacturing  firm. 

The  system  has  some  ardent  supporters  who  claim  that  by  it  the 
presence  of  the  patient  is  needed  only  for  the  impression  and  the  finish 
of  the  inlay,  the  rest  of  the  operation  being  done  in  the  patient's  absence 
and  by  a  laboratory  assistant  if  so  desired,  The  claim  is  plausible,  and 
from  the  fact  that  many  dentists  use  this  process,  it  is  worthy  of 
consideration. 

Dr.  F.  T,  Van  Woert  is  an  ardent  supporter  of  this  form  of  operating, 
and  in  an  article  on  this  subject  says:  "The  essentials  necessary  for 
securing  an  accurate  impression  of  any  cavity  are  (1)  suitable  trays; 
(2)  proper  impression  material;  and  (3)  a  knowledge  of  its  manipula- 
tion. 

"  The  material  for  trays  which  has  given  me  the  most  satisfaction  is 
sheet  platinoid  of  32,  34  and  36  gauge,  because  it  has  a  rigidity,  to- 
gether with  more  pliability  than  any  other  metal  that  I  have  been  able 
to  find.  Another  very  good  quality,  while  not  essential,  is  that  it  has  a 
finely  finished  surface,  which  at  least  has  the  appearance  of  being  clean, 
and  is  pleasing  to  the  patient.  The  second  requisite  is  the  impression 
material,  and  while  it  is  a  matter  of  opinion,  personally,  I  prefer  that 
made  by  the  Detroit  Dental  Mfg.  Co.,  because  it  softens  at  a  lower 
temperature,  sets  quicker,  and  when  cold  is  as  hard  if  not  harder,  and 
gives  a  very  much  sharper  definition  of  detail  than  others  I  have  tried. 
After  forming  the  tray,  a  suitable  quantity  of  compound  is  heated,  the 
tray  held  over  the  flame  until  it  is  hot  enough  for  the  material  to  adhere 
to  it,  and  the  compound  then  pressed  into  a  cone-shaped  mass  with  the 
fingers  and  then  chilled.  The  surface  of  the  cone  should  be  held  in  a 
small  flame,  so  that  it  is  quickly  heated  to  the  point  of  running,  and 
then  forced  into  position,  and  either  compressed  air  or  cold  water  used 
for  setting  it. 

"  I  find  it  a  great  advantage  in  large  cavities  in  molars  and  bicuspids 

to  force  between  the  tray  and  adjoining  tooth  the  blade  of  a  thin  cement 

spatula  to  bring  up  a  sharp  line  at  the  cervix.    This  is  easily  removed 

after  the  chilling,  and  facilitates  the  removal  of  the  impression  as  well. 

21 


322  HIGH  FUSING  PORCELAIN  INLAYS 

This  is  frequently  advantageous  in  approximate  cavities  of  the  anterior 
teeth  also. 

"Method  of  Making  Amalgam  Models. — If  we  have  succeeded  in 
securing  an  accurate  impression,  it  is  only  the  beginning  of  a  successful 
ultimate  result,  and  the  next  procedure,  that  of  making  the  model, 
requires  as  careful  consideration  and  manipulation  as  any  part  of  the 
technic.  Various  materials  have  been  recommended  for  this  purpose, 
all  of  which  I  have  given  a  most  careful  and  impartial  trial,  and  I  am 
forced  to  the  conclusion  that  there  is  but  one  reliable  material,  and  that 
is  a  good  amalgam.  When  I  say  'a,  good  amalgam,'  I  mean  one  having 
good  edge  strength,  as  little  shrinkage  as  possible,  and  the  propert}^  of 
setting  quickly,  although  this  is  not  essential.  I  use  the  standard  alloy 
made  after  one  of  Dr.  Black's  formulse. 

"First  the  impression  must  be  embedded  in  plaster  to  a  sufficient 
depth,  and  with  enough  body  surrounding  it  to  permit  of  pressing  the 
amalgam  well  down  into  the  impression.  The  amalgam  is  then  mixed 
with  enough  mercury  to  make  it  very  plastic,  and  this  is  burnished  into 
place  with  suitable  instruments  until  the  impression  is  filled.  Then  the 
excess  of  mercury  can  be  eliminated  by  folding  a  piece  of  rubber  dam 
several  times,  and  placing  it  on  the  amalgam  and  pressing  upon  it  with 
the  thumb. 

"  The  mixing  of  the  amalgam  is  one  of  the  most  important  points  in 
the  procedure.  In  my  early  efforts  I  tried  to  fiU  these  impressions  as  I 
would  a  cavity  in  a  tooth,  and  the  force  required  in  burnishing  it  to 
place  invariably  marred  the  impression  which  resulted  in  an  imperfect 
model  of  the  cavity. 

"Advantages  of  Impression  Method. — If  we  succeed  in  getting  an 
accurate  model,  a  filling  made  to  fit  it  must  fit  the  cavity  which  it  repre- 
sents. This  being  the  case,  let  us  consider  the  advantages  to  be  derived 
from  the  impression  method :  first,  we  are  none  of  us  so  perfect  in  any 
branch  of  our  art  that  we  are  not  liable  to  make  mistakes.  Second,  it 
is  beyond  question  thai  we  all  have  many  accidents  that  are  just  as 
deplorable  as  the  mistakes  we  might  make,  and  when  such  happen  in 
the  direct  method  of  making  inlays,  we  are  obliged  to  acquaint  our 
patients  with  the  fact  that  we  have  erred,  or  met  with  a  misfortune  in 
the  form  of  an  accident,  either  of  which  is  humilitating  to  the  operator 
and  frequently  exasperating  to  the  patient,  and,  occasionally,  to  such 
an  extent  that  the  patient  loses  confidence  and  seeks  service  elsewhere. 

"We  will  take,  for  example,  porcelain  restorations.  In  the  direct 
method,  where  the  matrix  is  burnished  to  the  cavity,  which,  by  the  way, 
is  a  much  more  tedious  operation  than  that  of  taking  an  impression, 
we  have  confronting  us  the  possibility  of  some  distortion  in  its  removal, 
or,  perhaj)s,  in  the  handling  after  it  has  been  successfully  removed^  a§ 


SWAGING  THE  PLATINUM  MATRIX  323 

well  as  the  possibility  of  warping  in  the  fusing  of  the  porcelain  itself. 
There  is  still  further  the  difficulty  which  arises  in  many  cases  of  securing 
a  suitable  color,  or  just  the  proper  form  of  contour,  all  of  which  is  a  large 
combination  of  defects  which  remains  to  be  explained  to  the  patient. 

"The  impression  method  eliminates  all  of  these  difficulties.  In  the 
first  place,  the  matrix  is  secured  by  swedging  the  gold  into  the  die  with 
the  Brewster  press  (Fig.  329)  and  the  swedged  matrix  is  less  likely  to 
change  its  shape  when  removed  than  the  burnished  one.  The  shape  of 
the  swedged  matrix  can  be  retained  by  filling  it  with  a  hard  wax;  it  is 
then  removed  and  invested,  and  later  the  wax  washed  out.  Should 
the  filling  prove  a  failure,  another,  or  several  others,  if  necessary,  can 
be  made  without  the  patient's  knowledge;  and  where  the  question  of 
color  or  contour  is  liable  to  cause  trouble,  several  fillings,  varying  from 
a  light  to  a  dark  shade,  can  be  made;  or  if  it  be  a  troublesome  contour, 
several  of  different  shapes,  so  that  when  the  patient  presents,  the 
suitable  filling  can  be  selected  without  subjecting  him  to  another  or 
several  operations,  and  without  the  unnecessary  loss  of  time  to  the 
operator. 

"Cast-gold  Fillings. — The  same  procedure  is  applicable  with  cast- 
gold  inlays,  with  the  exception  that  the  wax  filling  is  fitted  to  the  tooth, 
as  described  by  Dr.  Taggart,  omitting  the  final  carving  of  detail  in  bite 
and  contour  which  should  be  done  to  the  die.  If  the  die  is  correct,  the 
wax  filling  will  go  to  place  without  difficulty;  but  one  is  surprised  to 
note  the  little  defects  in  the  filling,  such  as  here  and  there  a  small  point 
where  the  wax  has  not  conformed  to  the  sharp  edge  of  the  cavity  mar- 
gin. This  is  due  to  the  lack  of  resistance  at  such  places;  the  wax  being 
of  one  temperature  throughout  its  entire  body,  it  is  forced  by  the  occlu- 
sion from  inward  out,  and  on  a  line  with  the  cavity  margin.  It  may  be 
said  that  this  defect  can  be  remedied  by  running  a  hot  spatula  around 
the  line,  but  I  have  found  this  extremely  difficult,  particularly  at  the 
cervix.  It  is  also  claimed  that  such  defects  may  be  corrected  by  biu- 
nishing  the  gold  casting  after  it  has  been  cemented  to  place.  This  has 
proved  just  as  difficult  and  unreliable  in  my  hands;  and  it  is  a  potent 
point  that  these  difficulties  do  not  exist  when  cast  fillings  are  made 
from  the  impression  and  amalgam  model  properly  constructed." 

SWAGING  THE  PLATINUM  MATRIX. 

The  cavity  is  prepared  as  described  for  the  usual  method,  edges 
square,  margins  strong,  and  without  undercut.  Talcum  powder  is 
rubbed  into  the  cavity  and  on  the  adjacent  surfaces. 

Then  an  impression  is  taken  in  cement.  This  is  invested  in  plaster 
of  Paris,  and  the  surplus  cement  which  extended  around  the  tooth  on 


324 


HIGH  FUSING  PORCELAIN  INLAYS 


both  sides  of  the  cavity  is  trimmed  away  to  about  one-sixteenth  of  an 
inch  from  the  margins.  Additional  cement  is  then  mixed  to  a  very  stiff 
consistence,  the  fingers  being  dipped  in  talcum  powder  and  the  cement 


Fig.  329 


Fig,  330 


well  kneaded.    The  first  impression  is  surfaced  with  talcum,  and  this 
second  mix  pressed  into  the  first  one  and  allowed  to  stand  until  quite 


Fig.  331 


Fig.  332 


hard.  Then  separate  and  invest  this  second  impression  or  model  in  one 
of  the  steel  cups,  in  plaster,  or,  if  preferred,  in  one  of  the  very  shallow 
cups,  in  cement  or  sealing  wax.    Invest  so  that  the  center  is  slightly 


SWAGING  THE  PLATINUM  MATRIX 


325 


higher  than  the  edges  of  the  cup.  When  the  plaster  Is  hard,  place  a 
square  piece  of  platinum  (one  one-thousandth  of  an  inch  thick)  on  the 
cement  model.  With  pledgets  of  cotton  wool  press  the  platinum  down 
into  the  cavity;  put  into  the  swager,  with  a  water  bag  over  the  wool,  and 
swage.  Remove  from  the  swager  and  burnish  out  wrinkles  or  folds; 
then  anneal  well  in  the  furnace,  replace  on  the  model  and  re-swage  with 
water  bag,  but  without  the  wool.  Reverse  the  press  handles,  remove 
the  cup  from  the  cylinder,  and  examine  the  matrix.  If  any  wrinkles  or 
folds  still  remain  on  the  margins,  they  must  be  burnished  out;  and  if  the 
matrix  does  not  appear  to  be  perfectly  adapted  to  all  parts  of  the  cavity, 
it  should  be  again  annealed  and  then  subjected  to  harder  pressure  in 


Fig.  333 


the  swager.    Any  crack  in  the  matrix  at  the  bottom  or  near  the  bottom 
of  the  cavity  will  not  affect  the  fit  of  an  inlay. 

In  building  in  the  porcelain  where  the  cavity  is  a  large  one,  first  grind 
an  "inlay  rod"  to  fit  tightly  across  the  matrix  at  its  widest  part;  sur- 
round this,  except  upon  its  upper  surface,  with  foundation  body;  and 
when  it  is  quite  dry,  bake.  Keep  the  foundation  body  sufficiently  away 
from  margins  to  allow  for  the  thickness  of  enamel  body  necessary  to 
produce  the  desired  color.  When  baked,  return  to  the  model,  and  if 
baking  the  foundation  body  has  caused  any  change  in  the  fit  of  the 
matrix,*the  next  swaging  will  correct  it.  After  this  last  swaging  pro- 
ceed to  fill  in  the  enamel  body.    Lay  the  dark  shades  in  first  and  bake; 


326  HIGH  FUSING  PORCELAIN  INLAYS 

then  add  the  Hghter  colors  necessary  to  finish.  The  foundation  body 
first  baked  in  the  matrix  will  prevent  any  change  of  form  during  the 
baking  of  the  enamel  body. 

The  press  should  be  screwed  to  the  bench.  The  solid  rubber  is  for 
swaging  heavy  metal  cusps  and  also  for  inlays.  Should  a  water  bag 
break,  carefully  dry  out  the  cylinder  and  plunger.  Do  not  allow  any 
rust  to  accumulate  in  the  cylinder.  The  inlay  rods  above  mentioned  are 
made  of  high  fusing  material  and  are  of  assistance  in  large  contour  work 
by  other  methods. 

The  most  recent  appliance  for  this  process  is  the  Roach  model  press 
with  trays  which  are  cut  to  form  of  cavity  and  are  recommended  for 
bicuspids  and  molars  (Figs.  330,  331,  332  and  333). 


FUSING  PORCELAIN. 

For  many  years  there  was  much  controversy  regarding  the  qualities 
of  various  products,  particularly  between  the  advocates  of  a  high  heat 
porcelain  and  those  of  low  fusing  qualities.  While  this  question  is  still 
debatable,  it  is  an  indisputable  fact  that  in  America  porcelains  of  the 
higher  grade  have  the  preference.  This  may  be  from  the  fact  that 
the  manufacturers  of  artificial  teeth  in  this  country  have  always  used  a 
high  fusing  material,  and  as  the  product  has  stood  the  test  of  time,  it  is 
only  natural  to  apply  this  argument  to  the  inlay  question. 

English  tooth  body  fuses  about  400°  F.  lower  than  the  highest  fusing 
American  body,  which  places  the  English  on  our  list  as  a  medium  fusing 
material,  and  its  excellent  quality  is  indisputable;  in  fact,  the  majority 
of  our  inlay  bodies  fuse  at  a  medium  heat,  ranging  from  2150°  F.  to 
2300°  F.,  therefore  the  difference  between  this  fusing  degree  and  that 
of  low  body  of  1600°  F.  or  thereabouts  is  the  point  of  argument. 

When  porcelain  inlays  were  introduced,  the  standard  material  was 
the  continuous  gum  bodies  then  well  known  to  porcelain  workers  and 
put  on  the  market  for  their  use.  It  was  the  only  material  to  be  had,  and 
while  it  possessed  the  required  quality,  it  had  no  variety  of  shade. 
After  some  years  this  was  remedied,  and  the  advent  of  the  pyrometer 
enabled  us  to  learn  the  approximate  fusing  temperatures  of  the  old 
continuous  gum  bodies  which  were  found  to  be  about  2300°  F.  These 
bodies  have  not  been  much  improved  upon  either  in  quality  or  finish. 
The  first  low  fusing  material  was  introduced  in  1892  by  Dr.  Downie, 
but  was  not  satisfactory  for  inlay  work  because  of  its  poor  shades, 
although  it  was  quite  extensively  used  for  crowns.  A  few  years  later 
Ash  &  Sons  made  up  a  small  assortment  much  improved  in  shades. 
Dr,  Jenkins  introduced  his  low  fusing  enamel  in  1898.     After  this 


t'VBiNG  PORCELAtn  327 

date  manufacturers  of  porcelain  produced  an  assortment  suitable  to 
all  circumstances. 

The  wearing  qualities  of  various  porcelains  are  practically  equal  in 
certain  positions,  notably  in  cavities  not  extending  to  incisal  edges  or 
masticating  surfaces,  and  in  shallow  labial  cavities.  Low  fusing  porce- 
lain has  an  advantage  from  the  fact  that  its  opacity  prevents  the  cement 
from  changing  the  shade,  which  is  frequently  the  case  with  a  high 
fusing  and  more  translucent  body. 

Workers  of  higher  fusing  porcelain  will  be  more  or  less  conversant 
with  all  porcelains  and  their  variations,  because  this  field  is  greater 
and  has  practically  no  limitation;  but  a  low  fusing  porcelain  worker  is 
usually  at  sea  if  not  using  that  material,  while  anyone  accustomed  to 
the  higher  heats  can  fuse  the  lower,  provided  care  is  used  not  to  over- 
heat. Too  much  heat  is  fatal  to  low  fusing  body,  as  it  means  not  only 
loss  of  shade,  but  also  loss  of  strength.  The  same  rule  applies  to  all 
porcelains,  but  not  to  the  same  extent  if  the  porcelain  is  high  fusing, 
for  its  working  latitude  is  much  greater.  Low  fusing  material  is  usually 
molded  in  a  gold  matrix  which  is  invested.  Platinum  must  be  used 
as  the  matrix  for  higher  heat  porcelains,  and  no  investment  of  it  is 
necessary. 

As  pyrometers  are  commonly  used,  a  list  of  the  most  popular  bodies, 
and  approximate  fusing  points  will  assist  the  student,  bearing  in  mind 
that  these  figures  are  based  on  two-minute  tests,  with  conditions  favor- 
able for  accuracy. 

Low  fusing.  Medium  fusing. 

Ash  &  Sons,  1550°  F.  S.  S.  White's  Medium,  2100°  F. 

Jenkins,  1550°  F.  Ash  &  Sons'  "High,"  1900°  F. 

High  fusing. 
S.  S.  White's  Inlay,  2300°  F. 
Close's  Continuous  Gum,  2300°  F. 
Whiteley's  Inlay,  2200°  F. 
Whiteley's  Inlay  special,  2400°  F. 
Consohdated  Inlay,  2600°  F. 
Johnson  &  Lund's,  2500°  F. 

It  is  generally  conceded  that  fusing  porcelain  is  one  of  the  greatest 
difficulties  that  must  be  overcome  before  the  novice  can  feel  that  he 
has  made  any  advancement  toward  the  successful  making  of  an  inlay 
or  anything  in  which  porcelain  is  the  component  part.  It  is  an  indis- 
putable fact  that  this  part  of  the  work  is  a  veritable  stumbling  block, 
and  the  cause  of  much  discouragement  which  is  only  overcome  by  per- 
sistent practice,  for  without  this  necessary  knowledge  successful  results 
are  not  possible. 

Porcelain  may  have  a  fusing  point  as  low  as  1600°  F.,  and  varying 
to  2600°  F.  or  even  higher,  therefore  the  operator  must  become  familiar 
with  these  varied  heats  and  their  productions.    This  will  mean  contin- 


328  HIGH  FUSING  PORCELAIN  INLAYS 

uous  application  and  training  the  eye  to  the  various  stages  and  changes 
of  the  material.  Using  a  timepiece  with  a  pyrometer  will  be  of  great 
assistance,  but  the  personal  equation  is  always  the  dominant  factor,  and 
herein  lies  the  difficulty  of  giving  directions  that  will  be  accurate 
under  all  conditions.  Before  the  advent  of  the  pyrometer  the  eye  was 
the  only  test  of  heat,  therefore  to  the  beginner  this  device  has  consid- 
erable value,  together  with  the  fact  that  the  fusing  points  of  the  numer- 
ous porcelains  are  known.  Thus  a  certain  time  by  the  watch  with  the 
fusing  point  of  the  porcelain  already  known  and  the  pyrometer  showing 
the  temperature,  the  fusing  of  porcelain  seems  comparatively  easy. 
Various  sizes  of  porcelain  require  different  heats,  therefore  it  is  abso- 
lutely necessary  to  know  porcelain  in  all  its  changes,  without  any 
assistance  whatever,  otherwise  the  work  will  be  either  over  or  under- 
fused,  and  only  by  chance  will  it  be  correct  if  the  machines  are  depended 
upon  entirely.  There  can  be  no  difference  of  opinion  on  this  fact, 
therefore  the  best  equipment  is  the  personal  knowledge  which  makes 
one  independent  of  any  appliance  or  set  of  rules  and  regulations.  It 
is  generally  contended  that  exposing  the  eye  to  such  severe  changes  of 
light  is  injurious,  and  this  may  be  true  beyond  a  certain  point,  viz., 
2300°  r.,  a  temperature  sufficient  for  the  majority  of  our  porcelains. 
There  is  a  product  by  a  well-known  firm  which  requires  a  heat  of 
2600°  F.,  and  there  is  no  doubt  that  the  eyes  should  be  protected 
from  the  glare  of  this  heat,  which  is  unnecessarily  high,  especially  for 
inlay  work. 

As  electric  furnaces  are  most  commonly  used  for  fusing  porcelain,  it 
is  not  very  difficult  for  the  student  to  become  familiar  with  the  various 
changes  of  heat  as  regulated  by  the  rheostat,  and  thereby  know  what 
step  will  fuse  a  certain  known  product.  For  instance,  the  first  step 
on  the  majority  of  furnaces  will  fuse  a  low  fusing  body  of  1600°  F.  in 
probably  one  minute  or  even  less,  but  the  same  heat  will  fuse  a  much 
higher  porcelain  if  given  longer  time.  Then  again,  voltage  must  be 
considered,  for  in  many  cases  it  is  only  approximate,  sometimes  vary- 
ing three  or  four  points  less  or  that  much  more,  and  still  coming  under 
the  class  of  110  volts  direct.  This  fact  is  particularly  noticeable  in 
local  establishments  such  as  office  buildings.  The  alternating  current 
is  usually  more  even,  that  of  220,  however,  being  very  strong  and 
harder  on  the  furnace  muffles. 

The  best  fusing  is  obtained  by  inserting  the  porcelain  at  the  lowest 
temperature  and  gradually  and  slowly  raising  the  heat  until  the  fusing 
point  is  obtained,  thus  passing  the  material  through  its  various  stages 
of  condensation.  These  stages  are  called  "biscuiting,"  and  a  porcelain 
partially  fused  may  be  called  a  medium  or  hard  biscuit.  In  the  latter 
condition  the  porcelain  has  a  half  glaze  and  has  shrunk  to  a  solid  mass 


FURNACES  329 

and  is  ready  for  the  additional  material  required  to  give  form.  Then 
the  porcelain  can  be  fired  until  it  has  the  finished  gloss,  which  is 
determined  by  the  eye  of  the  manipulator.  The  best  results  are  always 
obtained  by  underfusing  the  first  bake,  because  several  high  heats  will 
overfuse  the  groundwork  which  reduces  its  strength  and  solidity. 
Using  a  porcelain  of  slightly  lower  fusing  point  the  finishing  will  obviate 
this  tendency,  which  is  detrimental  to  the  whole  work. 

As  an  instance  of  this,  note  a  manufactured  tooth  which  is  finished 
in  one  baking,  and  the  same  directions  are  applicable  to  carved  teeth 
for  special  cases.  A  student  will  readily  learn  the  proper  glaze 
required  if  he  will  take  any  plain  or  plate  tooth  and  apply  porcelain  to 
its  surface  and  watch  the  various  changes  until  his  material  has  reached 
the  same  condition.  This  simple  experiment  will  also  help  him  to 
recognize  the  heat  required  for  these  changes  and  ultimately  enable 
him  to  acquire  self-confidence  in  the  management  of  the  fusing  process. 

Porcelain. — Porcelain  bodies  made  for  inlay  purposes  are  to  be  had 
in  great  variety,  both  in  fusing  point  and  texture;  in  fact,  there  is  such 
a  number  for  choice  that  the  unexperienced  must  necessarily  be 
bewildered. 

However,  this  difficulty  will  settle  itself  like  many  others  that  may 
at  one  time  have  been  just  as  perplexing. 

FURNACES. 

The  advancement  in  the  matter  of  furnaces  has  been  so  rapid  that 
less  than  thirty  years  ago  the  user  of  porcelain  depended  on  such  an 
apparently  crude  appliance  as  is  shown  in  Fig.  336  (old  coke  furnace), 
and  yet  the  beautiful  porcelain  dentures  and  carved  work  of  the  older 
dentists  have  not  been  surpassed. 

It  was  early  recognized  that  a  small,  quick  heating  appliance  was  a 
necessity,  and  this  difficulty  was  solved  by  Dr.  C.  H.  Land  by  inventing 
the  first  gas  furnace  in  1886.  This  machine,  while  a  great  improve- 
ment, was  slow  and  tiresome,  as  the  constant  use  of  bellows  was  neces- 
sary for  half  an  hour  before  the  furnace  was  hot  enough  for  use.  A 
smaller  and  quicker  gas  furnace  succeeded  this,  more  applicable  for 
inlays  and  crowns,  and  was  successfully  used  until  superseded  by 
electrical  outfits,  which  have  the  advantage  of  cleanliness,  purity,  and 
noiselessness. 

A  gas  furnace  is  noisy  and  gives  much  trouble  in  carbonizing  the 
porcelain,  or  as  it  is  usually  termed  "gassing."  Fortunately,  that  is  a 
discouragement  of  the  past,  for  electricity  has  reduced  fusing  cares  to 
the  minimum.  Other  furnaces  of  that  time  were  the  Parker-Stoddard, 
Downie,  and  Fletcher. 


Fig.  334. — Custer  No.  1,  for  crown,  bridge  and  inlay  work. 


Fig.  335. — Custer,  No.  2,  for  crown,  bridge,  inlay  and  continuous  gum  work. 


FURNACES 


331 


Dr.  L.  E.  Custer  invented  the  first  electric  furnace  in  1894,  and 
while  it  was  a  distinct  improvement,  there  was  much  trouble  in  muffle 
wires  burning  out,  which  caused  much  delay  and  retarded  the  general 


Fig.  336.— Old  style  coke 
furnace. 


Fig.  337. — The  Hammond  furnace  No.    1. 


Fig.  338. — ^S.  S.  White  furnace  with  pyrometer  attachment. 


332  HIGH  FUSING  PORCELAIN  INLAYS 

use  of  this  class  of  furnace.  The  Custer  electric  furnaces  (Figs.  334  and 
335)  as  now  perfected  are  practically  useful  and  are  strong  favorites. 
Five  years  later  the  Hammond  was  patented,  and  immediately  became 
popular  from  the  fact  that  a  "damaged"  muffle  could  be  replaced 
immediately. 

This  furnace  has  remained  a  favorite  until  the  present  time,  but  is 
being  gradually  replaced  by  the  S.  S.  White  Co.'s  new  furnace  (Fig.  338), 
which  is  similar,  but  improved  in  certain  details,  and  it  is  also  arranged 
with  pyrometer  attachment. 

In  1902  the  Pelton  appeared.  Besides  these  furnaces  there  are  sev- 
eral others  distinct  in  form,  and  all,  with  few  exceptions,  have  a  pyro- 
meter attachment.  They  are:  the  Fletcher,  Peck,  Gerhardt,  and 
Roach,  and  others  including  the  Price,  which  has  been  withdrawn, 
although  Dr.  Price  was  the  first  to  apply  the  pyrometer. 

In  addition,  furnaces  are  also  made  for  gasoline  use.  The  principal 
types  are  the  Turner  and  Brophy.  They  are  of  great  value  to  the 
out-of-town  dentist,  because  they  not  only  fuse  porcelain,  but  have 
equal  facility  in  blowpipe  work  and  metal  heating,  thus  enabling" 
those  not  possessing  gas  or  electricity  to  be  practically  on  the  same 
footing  with  the  city  practitioner. 


PRODUCING  PROPER  COLORS  IN  PORCELAIN  INLAYS. 

The  pigments  most  commonly  used  in  the  manufacture  of  dental 
porcelains  are  precipitated  gold  and  platinum,  purple  of  Cassius  and 
the  oxids  of  gold,  titanium,  manganese,  cobalt,  iron,  uranium,  silver 
and  zinc.  The  colors  produced  by  the  use  of  these  pigments  in  varying 
proportions  are  red,  yellow,  blue,  green,  brown  and  gray.  Red  is  not 
used  extensively  by  inlay  workers.  All  gum  enamel  frits  are  tints  of 
red.  It  may  be  used  in  the  manufacture  of  browns  and  grays,  also  to 
build  the  gingival  portion  of  many  inlays. 

Yellow. — ^Yellow  is  the  most  important  color  for  the  porcelain 
worker.  It  is  used  to  form  the  body  of  most  inlays;  it  adds  brilliancy 
to  the  browns  or  grays  when  combined  with  them.  Yellows  of  a  greenish 
hue  tend  to  lose  their  luminosity  in  yellow  light.  Two  yellows,  in  their 
deeper  tones,  may  match  each  other  perfectly,  but  when  diluted  to 
give  hghter  tints,  may  differ  quite  widely.  One  may  be  of  a  greenish 
hue,  while  the  other  may  tend  toward  a  grayish. 

Blue. — ^This  color  is  used  to  build  the  body  of  the  incisal  or  occlusal 
portion  of  inlays  for  those  teeth  with  blue  incisal  edges  or  cusps.  There 
is  a  variation  in  tone  from  greenish  blues  to  those  of  a  reddish  hue. 
Blues  of  a  greenish  hue  appear  to  be  more  translucent. 


PRODUCING  PROPER  COLORS  IN  PORCELAIN  INLAYS      333 

Other  Colors. — Green  is  seldom  used  alone,  it  may  be  added  to  blue 
to  increase  its  translucency.  Browns  are  used  to  build  the  gingival 
portion  of  some  inlays  and  for  the  body  of  inlays  for  discolored  teeth 
with  a  brownish  hue.  They  may  be  added  to  yellows  to  modify  them. 
Grays  are  used  to  build  the  middle  and  incisal  or  occlusal  portions  of 
many  inlays.    They  are  also  used  to  tone  yellows  and  blues. 

Shading. — This  part  of  making  porcelain  inlays  is  the  most  difficult 
to  the  majority,  and  is  an  uncertainty  with  all  of  us.  The  problem 
of  shrinkage  is  an  unknown  quantity,  and  its  remedy  is  purely  mechan- 
ical, but  the  problem  of  shading  is  a  combination  of  various  considera- 
tions which  may  be  followed  most  minutely  and  then  the  object  may  be 
defeated  by  some  detail  not  always  possible  to  avoid,  and  this  most 
common  defect  is  caused  by  the  opaque  cements.  The  most  experi- 
enced have  this  discouragement,  but  it  can  be  decreased  by  using  a 
variety  of  shades  and  matching  carefully.  We  have  and  can  mix  an 
almost  endless  variety  of  porcelain  shades,  but  this  is  only  a  part  of  the 
requirement,  for  position  and  tooth  density  must  also  be  considered, 
together  wdth  quantity  of  porcelain  to  be  fused.  There  is  also  the 
additional  difficulty  of  correct  fusing  to  reproduce  the  desired  shade. 

Overfusing  is  the  cause  of  more  shade  failures  than  any  other,  but 
practice  will  largely  obviate  this  trouble  as  in  other  difficulties.  The 
most  careful  directions  are  inadequate  as  compared  with  actual  demon- 
strations. After  all  has  been  said,  there  is  still  the  possibility  of 
failure  to  appreciate  this  phase  of  the  work,  because  this  part  of  it 
appeals  directly  to  the  artistic  sense,  and  can  only  be  comprehended 
through  observation  and  experience. 

The  difficulty  of  obtaining  colors  that  accurately  match  the  natural 
teeth  is  a  part  of  inlay  w^ork  w^hich  will  always  be  perplexing,  for  the 
teeth  are  largely  composed  of  organic  matter,  while  the  material  used  for 
repair  is  an  inorganic  composition,  differing  in  texture  and  density. 
When  selecting  the  colors  for  inlays,  note  the  various  shades  of  the 
natural  tooth,  for  frequently  there  are  three  or  more.  If  the  tooth  is 
vital  these  hues  have  a  distinction  which  is  lost  after  devitalization, 
thus  increasing  the  difficulties  of  matching,  but  if  the  variant  and 
uncertain  hues  of  the  pulpless  tooth  are  once  reproduced  in  an  inlay, 
the  subsequent  change  attending  the  cementation  is  not  so  marked 
because  of  the  pulpless  tooth  opacity. 

Position  of  the  inlay  is  a  factor  which  largely  governs  the  shade,  for 
the  shadow  problem  is  an  incident  which  forces  consideration  also. 
This  is  particularly  evident  in  proximate  cavities,  aud  is  remedied  to 
some  extent  by  making  the  inlay  a  shade  lighter,  and  is  also  controlled 
by  the  size  of  the  inlay.  A  lateral  incisor  being  much  smaller  than  a 
cuspid  must  be  treated  accordingly,  for  the  density  of  the  latter  is  much 


334  HIGH  FUSING  PORCELAIN  INLAYS 

greater  and  will  allow  a  deeper  shade.  Labial  inlays,  particularly 
bordering  the  gingival  line,  can  safely  be  made  a  shade  deeper;  but 
due  consideration  must  be  given  to  depth,  for  if  very  shallow,  the  por- 
celain should  be  of  greater  density  and  thus  overcome  the  cement 
change.  Inlays  of  this  kind  are  improved  in  texture  by  using  nearly  all 
base  body,  and  in  some  instances  low  fusing  porcelain  is  more  effective 
because  of  its  less  translucency. 

With  one  exception  all  inlay  porcelains  are  of  the  same  texture  from 
base  to  finish,  which  is  an  advantage  in  the  instance  just  cited,  but  the 
introduction  of  a  combination  consisting  of  a  basal  body  to  be  covered 
by  enamels  was  a  step  toward  procuring  more  natural  results  in  the 
majority  of  cases.  This  basal  body  represents  the  dentin,  which  in 
turn  is  covered  by  a  more  transparent  material  representing  the  enamel, 
thus  enabling  the  operator  to  blend  the  various  hues  of  shade  of  which 
the  natural  tooth  is  composed,  thereby  producing  a  translucent  effect 
not  possible  by  one  dense  porcelain  no  matter  how  expert  the  operator 
may  be. 

The  restoration  of  an  incisal  tip  or  corner  is  an  operation  that  requires 
much  practice  and  artistic  skill,  for  its  prominence  demands  perfect 
shading  and  adaptation.  An  operation  of  this  character,  while  testing 
the  ability  to  shade,  has  the  advantage  of  not  being  affected  by  the 
cement  line  because  of  greater  proportion  or  volume  of  porcelain.  How- 
ever, perfection  must  not  be  expected  because  there  is  always  the  differ- 
ence between  the  natural  translucency  of  tooth  structure  and  the 
unavoidable  density  of  porcelain  which  in  certain  positions  is  more 
noticeable  by  the  deflection  of  light  rays. 

A  common  mistake  in  shading  is  in  not  considering  the  difference 
between  the  volume  of  shade  exposed  on  the  porcelain  shade  guide  and 
the  quantity  required  to  fill  the  cavity. 

The  mixing  of  several  shades  to  gain  the  one  desired  is  largely  one  of 
intuition,  because  that  shade  cannot  be  known  until  properly  fused. 
This  difficulty  is  unfortunate,  but  cannot  be  avoided,  as  all  porcelain 
powders  are  practically  the  same,  with  the  exception  of  a  few  extreme 
shades,  and  herein  lies  the  difference  between  the  porcelain  artist  and 
the  painter  whose  pigments  are  mixed  and  the  desired  shade  revealed 
to  the  eye  by  simple  manipulation. 


CEMENTS  AND  MANIPULATION. 

It  is  generally  conceded  by  porcelain  operators  that  while  a  material 
of  this  kind  is  almost  an  ideal  filling,  it  falls  short  of  the  ideal  because 
W?  are  forced  to  use  as  an  attachment  a  substance  detrimental  to  that 


CEMENTS  AND  MANIPULATION  335 

aim  which  we  have  in  view,  namely,  the  absolutely  invisible  restora- 
tion of  tooth  form. 

What  cement  do  you  use?  is  an  ever-present  query  in  all  porcelain 
discussion,  for  when  there  is  a  failure  the  cement  is  generally  blamed 
for  it.  This  is  a  natural  deduction  when  it  is  considered  that  a  student 
in  porcelain  is  more  familiar  with  cement  than  with  other  parts  of  the 
operation,  and  if  there  is  a  failure  it  is  a  natural  supposition  that  it  is 
caused  by  poor  material.  A  cement  must  be  tenacious,  finely  ground, 
and  not  quick  setting,  and  of  a  quality  most  likely  to  resist  moisture 
when  setting,  for  it  is  not  always  possible  to  keep  the  work  free  from 
dampness  during  that  important  stage.  There  are  many  cements 
manufactured  that  have  these  requirements,  and,  like  other  materials 
with  similar  merits,  the  choice  rests  with  the  operator.  They  all  have 
the  same  disadvantage,  viz.,  opacity,  and  the  perfect  porcelain  opera- 
tion cannot  be  claimed  until  the  attaching  medium  is  transparent,  or 
nearly  so.  A  common  trouble  is  mixing  cement  too  thick,  thus  pre- 
venting proper  seating  of  inlay,  which  makes  the  joint  conspicuous  and 
unfinished.  When  this  occurs,  quickly  remove  and  cleanse  every  part 
thoroughly,  replacing  with  a  thinner  mixed  material. 

As  already  stated,  a  filling  of  porcelain  can  be  made  perfect  in  shape 
and  shade  and  the  texture  may  approximate  tooth  substance  in  a 
highly  satisfactory  manner;  but  immediately  upon  attaching  it  per- 
manently the  shade  is  changed  through  the  differences  between  the 
three  substances,  all  of  different  density,  which  come  in  close  contact, 
namely,  porcelain,  cement,  and  tooth.  The  cement  being  the  chief 
point  of  difficulty,  it  is  important  that  its  objectionable  features  should 
be  reduced  to  the  minimum. 

It  is  a  poor  cement  that  is  not  at  least  preservative.  Many  cements 
are  similar  in  manipulative  qualities  with  the  difference  of  slow,  medium 
and  quick  setting  tendencies.  Some  are  coarse  and  others  are  fine,  and 
a  few  have  a  combination  of  many  good  qualities  but  with  that  ten- 
dency to  "pack"  under  pressure  which  causes  annoyance  to  porcelain 
workers.  A  cement  closely  ground,  of  clear  color  and  medium  to  slow 
setting,  having  the  maximum  adhesiveness  with  the  least  amount  of 
powder,  is  what  is  recommended  for  a  successful  operation;  add  to  this 
one  that  has  the  greatest  amount  of  resistance  to  moisture  during  what 
is  usually  called  the  "setting"  period. 

Shading  a  cement  to  match  the  tooth,  or  to  lighten  or  darken  either 
the  porcelain  or  tooth,  or  both,  is  quite  bothersome  at  times  and  dis- 
appointing also.  It  is  of  considerable  assistance  to  mix  pellets  of  cement 
of  a  variety  of  shades  and  mount  them  in  the  most  convenient  manner 
to  allow  of  comparison,  in  that  way  saving  much  time  and  avoiding 
guess-work.    Whenever  possible  use  the  deepest  yellow  because  pur^ 


336  HIGH  FUSING  PORCELAIN  INLAYS 

calcined  oxid  of  zinc  is  quite  yellow,  and  its  chemical  combination  with 
phosphoric  acid  is  more  complete  than  when  otherwise  changed.^ 

For  instance,  a  white  or  very  light  yellow  is  made  so  by  oxid  of  zinc, 
thus  reducing  the  chemical  union  to  a  marked  degree;  and  the  same 
applies  to  darker  shades,  such  as  browns,  blues,  and  grays.  This  is  a 
point  of  some  advantage  in  setting  crowns  and  bridges,  or  whenever 
tenacity  is  a  first  requirement;  for  such  purposes  use  the  purest  yellow 
cement  just  as  it  comes  from  the  bolting  cloth  without  the  slightest 
manipulation  whatever. 

Some  years  ago  there  was  invented  by  Dr.  C.  H.  Land  a  material  in 
the  form  of  a  paste  or  paint  which  is  applied  to  that  part  of  the  porcelain 
intended  for  attachment,  and  which  is  then  subjected  to  heat  of  about 
2000°  F.,  thus  giving  the  porcelain  a  semi-vitrified  surface  composed 
of  a  substance  which  has  a  chemical  affinity  for  cement  and  acts 
as  a  medium  of  attachment.  This  promises  to  be  of  most  important 
assistance  in  many  cases  wherein  strength  is  of  first  consideration.  This 
material  is  called  "Media"  and  is  made  for  both  high  and  low  fusing 
porcelain,  and  will  also  be  found  of  value  in  repairing  facings  of  broken- 
crowns  and  bridges.  It  is  claimed  that  by  its  use  added  strength  is 
given  to  porcelain,  enabling  the  operator  to  extend  the  field  of  porcelain 
work  to  all  masticating  surfaces  or  other  places  where  the  strain  is  too 
great  to  use  porcelain  with  cement  as  the  only  attachment.  I  am 
prompted  to  mention  this  article  at  this  time,  because  I  am  interested 
in  any  and  everything  pertaining  to  this  branch  of  dentistry  that  may 
seem  to  promote  its  advancement,  and  also  because  I  have  privately 
and  publicly  made  tests  sufficient  to  give  confidence  in  its  merit  and 
convince  me  that  its  use  will  be  general  when  once  its  advantages  are 
known. 

UNDERCUTS  FOR  RETENTION  PURPOSES. 

Undercuts  are  not  necessary  in  the  tooth  cavities,  but  they  are 
imperative  in  the  filling  for  retentive  purposes,  and  are  made  with 
diamond  or  hard  rubber  and  corundum  disks.  The  latter  are  made  in 
such  a  variety  of  shapes  and  sizes  that  I  think  they  are  all  that  can  be 
desired,  for  their  cutting  power  is  equal  to  any  other  and  the  cost  very 
moderate.  Some  dentists  claim  that  cuts  in  the  porcelain  are  not 
necessary,  as  hydrofluoric  acid  will  roughen  the  surface  sufficiently  to 
stand  any  strain  and  that  cutting  of  porcelain  is  a  source  of  M^eakness 
which  is  not  occasioned  by  using  acid.  This  may  be  so  if  the  undercuts 
are  made  too  near  a  wearing  surface,  but  again  experience  is  our  test 

1  The  reader  is  referred  to  the  subject  of  cements,  Chapter  YII,  for  a  further  discus- 
sion of  this  subject. — Editor. 


UNDERCUTS  FOR  RETENTION  PURPOSES  337 

and  that  is  much  in  favor  of  undercuts.  In  very  small  inlays  acid  can 
be  used  to  advantage,  and  it  cannot  be  a  disadvantage  to  use  it  in  con- 
nection with  undercuts,  but  to  stake  your  trust  entirely  on  the  use  of 
acid  is  a  mistake  which  will  cause  trouble. 

The  method  of  using  it  on  very  small  inlays  where  an  undercut  is 
impossible,  is  to  soften  the  surface  of  a  piece  of  beeswax  or  paraffin  and 
embed  the  porcelain,  taking  care  not  to  have  edges  exposed,  then  drop 
a  little  acid  on  the  exposed  surface  and  allow  it  to  act  for  a  few  minutes ; 
then  wash  off  with  a  water  syringe. 

Placing  the  porcelain  in  position  is  a  part  of  this  work  that  requires 
extreme  care  and  frequently  great  patience.  Care  should  be  observed 
that  the  cavity  is  thoroughly  dry  before  the  insertion  of  the  filling 
and  kept  dry  until  the  cement  is  hard  enough  to  resist  moisture.  Use 
alcohol  freely  in  the  cavity  and  on  the  filling;  then  apply  hot  air  and 
mix  the  cement  to  a  creamy  consistence;  this,  when  applied  to  the 
cavity  walls,  almost  grows  there,  the  afiinity  is  so  great.  As  quickly  as 
possible  place  the  inlay  and  gently  press  into  position  and  hold  until  it 
becomes  fixed.  The  excess  of  cement  is  removed  by  a  small  piece  of 
firm  spunk.  In  proximate  work  I  use  waxed  silk,  drawn  over  the  surface 
gently  working  from  center  to  edges,  for  in  this  way  excess  cement  is 
easily  taken  from  between  the  teeth,  which,  if  left  until  hardened,  may 
loosen  the  filling  in  removing  it.  It  is  risky  to  try  to  get  everything 
clean,  much  better  to  leave  the  surfaces  a  little  smeary.  For  protection 
against  saliva  the  parts  should  be  covered  with  a  little  hot  paraffin. 
Rubber  and  sandarac  varnish  and  chloropercha  are  used  by  some,  but 
paraffin  is  the  favorite  because  it  is  cleaner  and  has  a  blending  effect 
which  is  quite  an  advantage  at  that  time,  for  the  tooth  is  lighter  by  the 
drying  process  and  the  cement  has  given  the  porcelain  a  more  opaque 
appearance;  so  it  is  just  as  well  that  the  patient  should  not  be  allowed 
to  inspect  the  result  too  closely  just  after  the  insertion  of  the  filling. 
The  time  to  show  it  to  the  patient  is  before  the  tooth  is  dried;  put  the 
filling  in  its  place  and  allow  the  saliva  to  be  the  cement  for  the  time 
being.    Frequently  it  is  never  seen  to  better  advantage. 

At  a  subsequent  sitting  the  edges  are  touched  with  a  stone,  and  the 
most  expert  operator  will  find  this  necessary,  for  the  tongue  will  find 
an  edge  if  he  cannot.  Fortunately  for  us,  after  a  time  there  is  a  blending 
of  the  porcelain  and  tooth  that  is  quite  gratifying;  but  it  is  better  to 
explain  this  to  the  patient,  for  some  people  are  unreasonable  enough 
to  expect  perfect  results  with  very  imperfect  agencies.  The  difficulties 
besetting  a  porcelain  worker  are  growing  less  each  year  because  when 
a  thing  is  demanded  and  that  demand  comes  through  confidence,  then 
allowances  are  made  which  will  assist  the  operator  provided  he  has 
skill  and  is  tactful. 
22 


338  HIGH  FUSING  PORCELAIN  INLAYS 

Cementation  of  Inlays  with  Silicate  Cements.  —  The  attachment  of 
inlays  with  siUcate  cement  greatly  adds  to  the  beauty  and  complete- 
ness of  the  inlay,  but  its  use  is  governed  by  certain  conditions.  This 
cement  is  not  so  adhesive  to  the  tooth  structure  as  oxyphosphate, 
therefore  a  decided  undercut  in  the  cavity  is  absolutely  necessary.  The 
silicate  cement  will  adhere  to  the  porcelain  with  small  assistance  and 
apparently  has  all  the  adhesiveness  necessary  in  the  cavity,  but  after  a 
time,  probably  a  few  months,  this  tenacity  is  diminished,  rendering 
an  undercut  a  necessity.  This  condition  is  a  reversal  of  the  qualities 
of  the  older  cements  and  may  be  remedied  in  the  future,  thereby  over- 
coming the  "cement  line"  objection.  A  porcelain  inlay  well  shaded 
and  adapted,  then  attached  with  a  silicate  cement,  is  a  perfect  restora- 
tion. . 


CHAPTER  VII. 

PROPERTIES  OF  FILLING  MATERIALS. 

By  MARCUS  L.  WARD,  D.D.Sc. 

Introductory. — The  chapter  on  properties  of  filling  materials  is 
written  as  a  separate  chapter  in  order  not  to  break  the  continuity  of 
thought  that  a  student  or  practitioner  of  dentistry  has  when  engaged 
in  a  study  of  the  operations  described  in  the  chapters  dealing  with  the 
practice  of  dentistry.  This  chapter  is  intended  to  be  more  a  corre- 
lation of  the  more  important  data  on  the  physical  and  chemical  proper- 
ties of  materials  used  in  the  practice  of  dentistry  than  a  treatise  on 
practice.  It  appears  to  have  been  customary  in  former  years  to  omit 
data  of  this  nature  from  text-books  on  operative  dentistry  and  to  refer 
the  readers  of  such  work  to  text-books  on  metallurgy,  which,  in  most 
instances,  have  not  treated  the  subject  with  specific  reference  to  oper- 
ative dentistry.  This  practice  on  the  part  of  editors  seems  to  have  be- 
come antiquated,  for  it  has  been  tried  long  enough  to  have  produced 
better  results  if  it  had  possessed  much  merit.  It  is  hoped,  therefore, 
that  the  manner  of  treating  the  subject  and  the  close  promixity  of 
the  data  in  question  to  the  data  on  the  more  practical  part  of  dentistry 
will  result  in  a  better  understanding  of  the  materials  that  are  in  so  gen- 
eral use.  Gold  is  treated  comparatively  briefly  because  the  use  of  all 
the  available  data  on  it  does  not  seem  warranted  in  a  text-book  on 
operative  dentistry,  and  because  students  of  dentistry  usually  receive 
more  instruction  on  this  subject  than  on  most  others.  The  subject  of 
amalgam  has  included  in  it  a  discussion  of  the  subject  of  manipulation 
because  many  of  the  properties  depend  so  largely  upon  the  manipu- 
lation. Porcelain  has  been  omitted  from  the  list  of  materials  con- 
sidered, primarily  because  the  data  concerning  it  are  largely  in  the 
hands  of  the  manufacturers  and  secondarily  because  the  compara- 
tively limited  knowledge  of  the  subject  is  well  covered  in  Chapter  V. 


GOLD. 

Gold  is  one  of  the  first  metals  with  which  man  became  acquainted. 
As  a  result  of  this  an  appreciable  amount  of  data  has  accumulated, 

(339) 


340  PROPERTIES  OF  FILLING  MATERIALS 

for  from  the  first  gold  has  attracted  much  attention  because  of  its 
wonderful  properties  and  intrinsic  value.  In  the  search  for  gold, 
men  have  endeavored  to  produce  it  by  the  transmutation  of  base 
metals,  and  in  doing  so  have  made  many  discoveries  which  have 
probably  aided  in  laying  the  foundations  for  the  science  of  metallurgy. 
It  is  doubtful  if  the  metallurgy  of  some  metals  would  have  been  as 
well  developed  if  it  had  not  been  for  the  work  done  on  gold.  On 
account  of  the  part  it  has  played  in  the  development  of  metallurgy, 
its  intrinsic  value  and  wonderful  properties,  gold  has  been  termed  the 
most  noble  of  metals.  A  solid  mass  of  pure  gold  is  yellow  in  color, 
but  when  finely  divided,  as  it  is  when  volatilized,  or  when  precipitated 
from  solution  it  may  be  violet,  ruby,  purple  or  brown  in  color.  Com- 
mon examples  of  violet  gold  are  seen  when  the  oxyhydrogen  blow-pipe 
has  been  used  to  melt  gold  for  casting  purposes,  the  gold  having  col- 
lected around  the  edges  of  the  cold  casting  ring.  Examples  of  brown 
gold  may  be  observed  in  the  various  sponge  golds  in  the  market  for  the 
purpose  of  filling  teeth.  If  a  very  thin  sheet  of  gold  be  supported  upon 
a  glass  plate,  it  appears  green,  on  account  of  transmitted  light.  If  the 
plate  containing  the  gold  be  heated  to  250°  C.  it  will  appear  white,  due 
to  the  formation  of  aggregates  of  gold  between  which  the  light 
passes.  Various  colored  golds  may  be  produced  by  alloying  with 
other  metals.^ 

Gold  possesses  a  very  high  specific  gravity.  SchnabeP  gives  the 
specific  gravity  of  gold  as  follows:  19.30  to  19.33  at  17.4°  C.  after  it 
has  been  fused  and  cast.  Rose^  gives  it  as  19.33  to  19.34  when  it  has 
been  compressed  and  19.55  to  20.72  when  precipitated  by  ferrous 
sulphate.  Hoffman^  lists  gold  along  with  other  metals  in  a  table  to 
show  the  effect  of  rolling  and  hammering  upon  specific  gravity.  His 
figures  are  19.25  for  cast  gold  and  19.35  for  hammered  gold.  The 
specific  gravity  of  fillings  made  from  foil  varies  between  14  and  18  for 
good  operators. 

The  melting-point  of  gold  is  usually  given  by  dental  authorities 
above  2000°  F.  and  by  metallurgical  authorities  as  1063°  to  1065° 
C.  The  most  reliable  authority,  however,  gives  it  as  1064,4°  C. 
(1947.92°  F.) 

The  approximate  melting-points  of  the  various  gold  products  of 
the  J.  M.  Ney  Company  are  published  by  this  company  according  to 
the  table  on  the  opposite  page. 

1  For  a  discussion  of  this  subject  the  reader  is  referred  to  the  various  works  on  metal 
coloring. 

2  Handbook  of  Metallurgy,  vol.  i.  '  Metallurgy  of  Gold. 
4  General  Metallurgy. 


GOLD  341 

Degs.  Fahrenheit.  Degs.  Centigrade. 

2200  Ney-Oro  gold  plate  No.  3 1204 

2100  Ney-Oro  "elastic"  gold 1150 

2075  Ney-Oro  gold  plate  No.  1 1135 

1975             Ney's  high  fusing  clasp  metal 1080 

1975  Ney-Oro  gold  plate  No.  2 1080 

1960  Ney-Oro  casting  gold  "E" 1070 

1945             Ney's  pure  gold  (24  k.) '  1063 

1945  Ney-Oro  casting  gold  "A" 1063 

1940             Ney's  green  backing 1060 

1900  Ney-Oro  casting  gold  "B" 1035 

1900             Ney's  light  22  k.  plate 1035 

1825             Ney's  dark  22  k.  plate ; 1010 

1800  Ney-Oro  casting  gold  "C" 980 

1735             Coin  gold  (U.  S.  standard) 946 

1735  Ney-Oro  casting  gold  "F" 946 

1725             Ney's  regular  clasp  metal 940 

1675  Ney-Oro  gold  solder  No.  84 915 

1625             Ney's  gold  solder  for  22  k 885 

1550  Ney-Oro  gold  solder  No.  76 840 

1525             Ney's  gold  solder  for  20  k 820 

1450  Ney-Oro  gold  solder  No.  68 785 

1425             Ney's  gold  solder  for  18  k 770 

The  gold  products  of  the  S.  S.  White  Company  have  approximately 
the  following  melting-points  according  to  this  company's  statements: 

Melting-point. 
Degree  Degree 

Metal.  F.  C. 

Plates  and  Wires: 

18  k 1740  949 

20  k 1729  943 

No.  1  clasp 1850  1010 

No.  3  clasp 1760  960 

Plates: 

18  k.  light 1895  1035 

Coin 1706  930 

22  k.  dark 1859  1015 

22  k.  light 1913  1045 

Solders: 

For  14  k.  . 1360  738 

16  k 1441  783 

18  k 1470  709 

20  k 1521  827 

Coin 1567  853 

22  k 1578  859 

The  boiling-point  of  gold  at  atmospheric  pressure  is  approximately 
2200°  C.  The  volatility  of  gold  is  given  by  Schnabel  as  very  little  at 
1045°  C.  and  barely  appreciable  at  1075°  C.  He  states,  however,  that 
at  1250°  C.  it  is  four  times  greater  than  at  1100°  C.  The  specific  heat, 
or  ratio  between  the  heat  required  to  raise  the  temperature  of  water 
and  metal  1°  is  given  as  0.030  to  0.032. 

Ductility,  or  the  property  of  gold  to  extend  by  traction  as  compared 
with  some  of  the  common  metals,  is  as  follows:  gold,  silver,  platinum, 
iron,  nickel,  copper,  aluminum,  zinc,  tin,  antimony.  It  is  stated  that 
one  grain  of  gold  can  be  drawn  into  a  wire  160  yards  long  and  can  be 


342  PROPERTIES  OF  FILLING  MATERIALS 

beaten  into  a  sheet  T^oViTTr  of  an  inch  thick.  Schnabel  states  that 
Reaumur  succeeded  in  producing  a  sheet  0.00000087  of  an  inch  thick. 

Malleabihty,  or  the  property  of  being  extended  in  all  directions 
without  cracking  when  rolled  or  hammered,  is  shown  to  be  in  the  same 
position  as  ductility  with  the  order  of  the  other  metals  somewhat 
changed.  It  is  as  follows:  gold,  silver,  aluminum,  copper,  tin,  platinum, 
lead,  zinc,  iron,  nickel. 

The  hardness  of  gold  as  compared  with  some  of  the  other  non-ferrous 
metals  is  given  in  hardness  numbers  on  a  Brinnell  hardness  testing 
machine  as  follows: 

Copper 74.00 

Silver 59.00 

Antimony 55.00 

Gold 48.00 

Zinc 46.00 

Aluminum 38 .  00 

Tin 14.00 

The  hardness  of  gold  and  the  principal  alloys  of  gold  in  use  in 
dentistry  were  recently  tested  with  a  Shore  Scleroscope  and  found  to 
be  as  follows:^ 

Hardness  of  Various  Dental  Golds. 

Each  of  the  valaes  is  the  average  of  ten  readings  on  a  Shore  Scleroscope. 

Ney's  Ney's  Ney's  Ney's  Ney's  Ney's  Ney-Oro  S.S.  White 

24  k.         22  k.  22  k.  20  k.  22  k.  20  k.  18  k.         "E"  clasp 

L.  C.  D.  C.  plate.  solder,  soder.  solder.        clasp  metal. 

metal. 

Cast       ...        4.9  5,5  12.5  18.3  25,4  33.8  59.8         25.4  37.9 

Rolled    .      .      .      33.0         45.2  52.0  70.7  73.9  79.1  80.7         86.5  80.4 
Annealed^  after 

rolling      .      .        5.8  6.4  14.3  22.5  30.8  39.9  42.9         50.9  41.2 

The  hardness  of  a  metal  varies  with  the  treatment  given  it.  The 
hardness  values  of  the  common  dental  golds  are  shown  in  the  table  to 
be  high  when  rolled  or  hammered,  low  when  cast  and  somewhat  between 
the  two  when  annealed  after  rolling  or  hammering,  with  the  exception 
of  18-carat  solder.  As  a  rule,  metals  are  soft  when  cast  and  hard  when 
rolled  or  hammered.  Alloys,  especially  the  more  complex  ones,  do 
not  follow  this  rule  but  may  be  either  hard  or  soft  when  cast.  A  good 
example  of  this  is  shown  in  the  softness  of  the  clasp  metals,  which  are 
soft  when  cast,  and  the  18-carat  solder,  which  is  hard  when  cast,  both 
of  which  contain  four  metals.     (See  paragraph  on  annealing.) 

The  rate  of  cooling  may  cause  the  hardness  of  a  metal  to  vary,  and 
usually  has  a  marked  effect  upon  the  hardness  of  alloys.  The  author 
recently  subjected  the  various  golds  shown  in  the  table  to  different 

1  These  tests  were  made  for  this  chapter  by  Marcus  L.  Ward  and  E.  O.  Scott. 

2  The  annealing  was  done  by  heating  to  redness  and  quenching. 


GOLD  343 

rates  of  cooling  and  found  that  the  practice  of  dentists  of  heating  to 
redness  and  quenching  produced  the  results  desired  in  the  higher  carat 
golds  and  solders,  but  as  the  18  and  lower  carat  solders  and  clasp 
metals  were  reached  the  results  were  very  irregular.  In  fact,  they 
were  so  irregular  that  it  seemed  inadvisable  to  publish  them  until  they 
could  be  confirmed  with  further  work.  It  seems,  therefore,  in  order 
to  obtain  the  desired  properties  from  the  complex  alloys,  such  as  the 
solders  and  clasp  metals,  that  research  work  on  cooling  is  necessary 
for  each  one  of  them  and  that  instructions  should  be  given  for  the 
cooling  of  such  products. 

The  term  hardness  may  often  be  taken  as  synonymous  with  strength. 
This  is  not  always  true,  however,  for  the  term  hardness  is  used  to 
express  at  least  five  ideas:  resistance  to  scratching,  to  indentation,  to 
elastic  impact,  to  cutting  and  to  permanent  deformation,  and  the 
term  strength  is  used  to  define  resistance  to  at  least  five  forces,  as 
follows:  forces  which  fracture,  twist,  pull,  compress  and  change 
shape.  A  good  illustration  of  hardness  without  toughness  or  proper 
resistance  to  all  stresses  is  the  hardness  of  the  minerologist,  as  follows: 
showing  ten  minerals  in  the  order  of  their  hardness:  talc,  gypsum, 
calcite,  fluorspar,  apatite,  feldspar,  quartz,  topaz,  corundum  and  the 
diamond. 

Metals  or  alloys  which  are  as  hard  and  brittle  as  these  materials 
would  be  of  little  use  in  dentistry,  for  they  would  not  resist  the  forces 
of  mastication.  Whenever  the  terms  hardness  and  strength  are  used 
synonymously,  therefore,  it  should  be  understood  that  strength  implies 
both  hardness  ard  toughness. 

Gold  which  has  been  hardened  by  rolling  or  hammering  may  be 
softened  by  annealing,  which  is  usually  done  by  heating  the  gold  to 
redness  and  quenching  in  hydrochloric  acid  (50  per  cent,  or  more)  or 
in  sulphuric  acid  of  the  same  strength.  The  former  is  preferred  by 
many  for  the  reason  that  it  is  not  so  destructive  to  linen  or  clothing 
with  which  it  may  come  in  contact.  It  is  not  accessary  to  heat  gold 
to  redness  in  order  to  anneal  it.  It  has  been  shown^  that  if  gold  is 
heated  to  150°  C.  and  held  at  this  temperature  for  thirty  minutes  or 
longer  it  will  become  quite  well  annealed.  Other  metals  may  be 
annealed  at  comparatively  low  temperatures  if  the  heat  be  main- 
tained for  a  long  time,  and  like  gold  will  be  annealed  more  completely 
and  quickly  with  slight  vibration  in  connection  with  the  heat.  The 
maaner  of  annealing  the  complex  alloys,  as  has  been  stated,  is  not 
known.  Dentists  usually  give  them  the  same  treatment  as  pure  gold, 
though  it  seems  likely  that  investigation  will  show  this  practice  to  be 

^  Rose,  Institute  of  Metals, 


344  PROPERTIES  OF  FILLING  MATERIALS 

erroneous  in  some  cases.  In  this  connection  it  may  be  stated  that 
Gulliver^  and  others  refer  to  the  hardening  of  steel  by  quenching  and 
the  softening  of  bell  metal  by  the  same  treatment.  When  a  pure  metal 
is  chilled  rapidly  from  a  molten  condition  about  the  only  difference  that 
is  observed  from  the  normal  structure  is  the  smallness  of  the  grains. 
This  is  because  the  number  of  centers  of  crystallization  have  been 
increased.  If,  on  the  other  hand,  the  metal  is  allowed  to  cool  more 
slowly  the  centers  of  crystallization  are  fewer  in  number  ^nd  the 
metal  appears  more  coarse-grained.  This,  obviously,  will  alter  mark- 
edly the  physical  properties  of  some  metals  and  most  alloys. 

The  tensile  strength  of  gold  is  given  by  Hoffman  as  37,000  pounds 
per  square  inch  for  hard-drawn  wire  and  24,000  pounds  per  square 
inch  for  soft-drawn  wire.  It  is  probable  that  these  figures  refer  to 
unannealed  and  annealed  drawn  wire.  Hiorns  gives  the  tensile  strength 
of  gold  as  7  tons  per  square  inch,  but  does  not  state  whether  it  is 
annealed  or  unannealed.  It  is  strange  that  more  work  has  not  been 
done  on  the  strength  of  gold.  Perhaps  the  figures  available  are  quite 
accurate.  It  appears,  however,  that  they  hardly  represent  the  differ- 
ences that  should  exist  between  the  annealed  and  unannealed  metal.  It 
is  not  strange  that  compression  tests  have  not  been  made  on  gold,  for 
with  gold  as  with  many  metals  there  is  no  definite  crushing  point  under 
compressive  stress,  as  is  the  case  when  metals  are  subjected  to  a  tensile 
or  traction  test.  When  some  metals  are  subjected  to  a  compressive 
stress  they  simply  spread  when  the  elastic  limit  has  been  reached. 
Inside  of  this  point  they  return  to  the  original  form  after  the  load  is 
removed.  With  other  metals,  however,  and  with  some  alloys,  when  the 
elastic  limit  is  reached  there  is  a  definite  breaking-point.  Amalgams 
furnish  a  good  example  of  the  common  alloys  which  have  quite  definite 
breaking-points  and  for  which  a  compressive  stress  test  is  preferable 
to  a  tensile  stress  test. 

Gold  has  a  coefficient  of  linear  expansion  for  1°  C.  between  0°  and 
100°  of  0.0000144.  In  general,  when  heat  energy  is  added  to  a  body 
its  volume  changes.  Volume  change  is  known  as  cubical  expansion. 
In  the  discussion  of  expansion  and  contraction,  however,  one  dimen- 
sion is  usually  all  that  is  considered.  This  is  along  a  linear  dimension 
of  the  body  and  is  known  as  linear  expansion.  The  coefficient  of  expan- 
sion increases  with  increases  in  temperature  and  is  quite  marked  near 
the  melting-point.  It  also  varies  with  the  physical  condition  of  the 
metal.  An  operation  which  increases  the  density  will  also  increase  the 
expansion.  It  is  a  general  rule  that  all  metalfe  expand  when  heated  and 
contract  when  cooled.    There  are  one  or  two  exceptions,  however. 

1  Metallic  Alloys. 


GOLD  345 

Copper,  bismuth  and  antimony  are  among  the  metals  claimed  to 
expand  while  cooling.  It  is  claimed  that  copper  expands  while  cooling 
only  under  conditions  which  have  been  favorable  to  occlusion  and  dis- 
solving of  gases  which  are  expelled  during  the  cooling  process.  For 
bismuth  and  antimony,  however,  no  explanation  seems  to  have  been 
made  which  would  account  for  the  phenomenon  of  expansion  when 
cooling.  Coefficients  of  expansion  and  contraction  are  for  given  tem- 
peratures only,  for  as  the  melting-point  of  most  metals  is  reached  the 
volume  is  decidedly  increased. 

Shrinkage  being  the  reverse  of  expansion  may  be  estimated  by  the 
expansion,  as  a  general  rule.  Shrinkage,  therefore,  is  very  marked  as 
the  metal  changes  from  the  liquid  to  the  solid  state  and  corresponds 
to  the  expansion  at  other  temperatures  than  the  ones  which  bring  it 
to  a  liquid  state.  It  would  be  interesting  to  know  the  coefficient  of 
volume  change  for  gold  at  its  liquefying  point,  for  with  the  advent  of 
the  casting  process  into  general  use  it  is  necessary  to  fill  molds  of  every 
conceivable  shape  with  gold  or  gold  alloys  in  order  to  meet  the  demands 
of  modern  dentistry.  The  only  research  that  has  been  done  to  deter- 
mine the  shrinkage  of  gold  in  casting  it  into  molds  would  lead  one  to 
believe  that  it  was  about  2  per  cent.  The  absence  of  some  very  essen- 
tial data  in  connection  with  this  work  makes  it  of  little  value.  It  is 
probable,  however,  that  the  total  shrinkage  of  gold  from  a  state  of 
fluidity  which  would  permit  the  filling  of  a  mold  for  a  filling  is  somewhat 
above  1  per  cent.,  depending  upon  the  temperature  of  the  gold  when 
it  is  forced  into  the  mold.  Many  operators  make  the  mistake  of  casting 
gold  at  or  near  its  boiling-point,  at  which  the  gold  is  in  a  very  much 
expanded  condition,  and,  consequently,  must  result  in  an  excessive 
shrinkage. 

Numerous  theories  have  been  advanced  by  practitioners  of  dentistry 
about  the  excessive  shrinkage  of  gold  under  certain  conditions.  It  is 
probable  that  too  much  heat  has  been  used  or  the  gold  has  been 
alloyed  with  something  which  results  in  excessive  shrinkage.  It  should 
be  remembered  that  the  volume  change  of  many  alloys,  especially  the 
complex  ones,  cannot  be  calculated.  Metals  are  subject  to  volume 
change  from  changes  in  temperature,  but  alloys  have  volume  change 
from  changes  in  temperature  and  from  the  reaction  between  the  con- 
stituent metals  which  cannot  be  calculated. 

Pure  gold  can  be  welded  in  a  cold  state.  Ordinaril}^  welding  is  accom- 
plished by  bringing  the  metals  to  a  temperature  that  makes  them  pasty 
when  the  motion  of  the  molecules  is  so  accelerated  that  they  inter- 
penetrate or  diffuse  into  one  another  when  slight  pressure  is  applied. 
In  heating  readily  oxidizable  metals  it  is  necessary  to  exclude  the  air 
or  use  fluxes  which  will  slag  any  oxids  formed  and  form  a  somewhat 


346  PROPERTIES  OF  FILLING  MATERIALS 

impervious  coating.  Inasmuch  as  gold  does  not  oxidize  under  ordinary 
conditions,  or  have  the  ordinary  contents  of  the  air  condense  upon  its 
surface,  it  may  be  welded  in  a  cold  state.  There  are  certain  gases, 
however,  which  do  combine  with  and  condense  upon  the  surface  of 
gold  and  prevent  both  cohesion  and  welding.  The  following  are  said 
to  be  capable  of  condensing  upon  the  surface  of  gold  to  such  an  extent 
that  its  cohesion  and  welding  are  impaired:  carbon  dioxid,  sulphur 
compounds,  iodin,  the  various  oils  used  in  dentistry  and  other  volatile 
substances.  Chlorin  is  said  to  combine  with  gold  sufficiently  when  con- 
densed upon  the  surface  in  the  form  of  ammonium  chlorid  to  prevent 
cohesion  and  welding.  It  is  claimed  by  some  that,  as  a  result  of  this 
action,  ammonia  has  been  adopted  for  condensation  upon  the  surface 
of  pure  gold  to  make  cohesive  gold  non-cohesive. 

The  thermal  conductivity^  of  gold  is  53.20,  copper  being  73.60  and 
silver  100,  according  to  Hoffman.  The  electric  conductivity  of  gold 
has  been  given  by  Matthiessen  as  77.96,  copper  as  99.95  and  silver  as 
100,  all  of  which  were  drawn  metal.  Cast  metals  are  poorer  con- 
ductors than  those  which  have  been  hardened  by  drawing,  hammering 
or  rolling.    Conductivity  may  vary  with  purity  and  temperature. 

Gold  in  solid  form  is  said  to  absorb  gases  when  heated  to  redness 
and  in  spongy  form  at  ordinary  temperatures  (Schnabel).  Some  other 
writers  claim  that  gold  is  an  exception  to  the  general  rule  that  molten 
metals  absorb  gases  and  does  not  absorb  an  appreciable  amount.  The 
conclusion  that  seems  to  be  warranted  is  that  the  subject  is  not  well 
understood  at  the  present  time. 

Gold  is  not  soluble  in  a  single  acid  except  selenic  (Il2Se04).  It  is 
soluble  in  aqua  regia  on  account  of  the  chlorin  available.  Gold  is 
readily  dissolved  by  chlorin  or  any  substance  which  yields  chlorin. 
Gold  may  be  precipitated  by  organic  substances,  several  gases,  most 
metals  and  by  some  metallic  salts. 

Gold  does  not  oxidize  either  at  the  ordinary  temperatures  or  at 
elevated  ones.  Two  oxids  of  gold  are  claimed  to  exist,  however, 
aureus  oxid,  AU2O,  and  auric  oxid,  AU2O3.  The  former  results  when 
mercurous  nitrate  and  neutral  auric  chlorid  are  put  together  or  by 
treating  aurous  chlorid  or  bromid  in  the  cold  with  caustic  potash.  The 
latter  is  obtained  when  auric  chlorid  solutions  are  treated  with  some 
alkaline  substance.  Gold  is  not  acted  upon  by  sulphur  and  sulphur 
compounds  in  the  same  manner  as  most  metals  are.  With  free  sulphur 
it  does  not  combine  at  all  and  with  hydrogen  sulphid  it  does  not  appear 
to  combine  except  when  the  hydrogen  sulphid  is  introduced  into  solu- 
tions of  gold.  Gold  alloys  readily  unite  with  other  metals,  sometimes 
forming  definite  chemical  compounds. 

From  the  foregoing  it  is  clear  that  gold  is  one  of  the  most  perfect  of 


GOLD  347 

the  metals,  but  it  is  necessary  to  impart  to  it  a  greater  degree  of  strength 
than  it  alone  possesses,  for  the  manufacture  of  jewelry,  coins  and  many 
dental  restorations. 

Silver  and  copper  are  the  metals  most  commonly  used,  and  when 
used  in  small  quantities  do  not  alter  very  markedly  the  properties 
of  gold.  Copper  seems  to  produce  a  greater  change  in  properties  than 
silver.  The  effect  of  alloying  gold  with  10  per  cent,  of  copper  to  produce 
the  standard  coin  is  well  known.  The  effect  of  alloying  gold  with  silver 
is  less  well  known,  though  it  appears  quite  probable  that  in  the  future, 
as  restrictions  are  placed  upon  the  use  of  large  quantities  of  gold  in 
places  where  something  else  will  serve  quite  as  well,  there  will  be 
created  a  new  interest  in  alloys  of  gold  and  silver  for  many  large  cast- 
ings. The  difference  in  the  effect  of  alloying  gold  with  copper  and 
silver  is  shown  in  the  table  of  hardness  tests.  It  may  be  seen  that 
there  is  a  marked  difference  in  hardness  between  Ney's  dark  22  k. 
gold  and  22  k.  light  gold.  The  formula  of  each  may  be  seen  in  the 
following  list  of  formulae^  of  gold  plates  in  general  use : 

22  k.  dark  gold  plate.  22  k.  light  gold  plate.  20  k.  gold  plate. 

Gold  .      .      .      92.00  Gold       .      .      .      .92.00  Gold       .      .      83.25 

Silver       .      .        4.50  Silver     ....        7.70  Silver     .      .      12.00 

Copper    .      .        3.50  Copper  ....        0.30  Copper  .      .        4.75 

It  may  be  noted  that  almost  8  per  cent,  of  silver  has  made  practically 
no  difference  between  the  hardness  of  the  light  22  k.  gold  and  that  of 
pure  gold.  The  slight  difference  in  hardness  shown  is  probably  due  to 
the  very  small  amount  of  copper  contained  in  this  alloy.  Silver  and 
copper  unite  in  all  proportions  and  form  a  valuable  series  of  alloys, 
having  many  applications  in  the  arts.  Whenever  these  two  metals  in 
the  form  of  an  alloy  are  combined  with  gold  they  seem  to  have  a 
marked  influence  in  hardeniag  it,  as  may  be  observed  by  the  tests  on 
the  20  k.  gold  plate,  which  has  considerably  higher  percentages  of  both 
copper  and  silver  than  the  higher  carat  golds.  The  alloys  of  gold, 
silver  and  copper  are  also  sufficiently  tough  to  resist  the  forces  of  masti- 
cation when  used  in  the  quantities  which  are  permissible,  and  are  used 
in  large  quantities  by  dentists  in  the  coastruction  of  crowns,  bands, 
inlays  and  other  restorations. 

Zinc  is  also  used  to  alloy  gold  in  the  prod  iction  of  solders  for  the 
operations  which  require  the  union  of  the  various  parts  of  restorations. 
The  gold  solders  are  designated  as  22  carat,  20  carat,  18  carat,  etc.,  as 
the  case  may  be,  which  indicates  the  carat  of  the  gold  upon  which  they 
may  be  melted  without  loss  of  form  of  the  gold  plate.    The  following 

'  These  and  the  following  analyses  shown  for  the  various  alloys  of  gold  were  made  for 
this  chapter  by  E.  O.  Scott  during  the  early  part  of  1920  from  alloys  obtained  from  the 
market. 


348  PROPERTIES  OF  FILLING  MATERIALS 

formulse  of  three  of  these  alloys  show  that  they  are  not  of  the  carat 
that  they  are  named,  but  are  intended  to  be  used  upon  gold  of  the 
carat  marked  upon  them. 

Formula  of  Solders. 


22  k.  solder. 

20  k.  solder. 

18  k.  solder. 

Gold    . 

.      84.00  parts. 

Gold     .      .      76.00  parts. 

Gold     .      .      68.00  parts 

Copper 

7.50      " 

Copper       .      11.50      " 

Copper       .      14.50      " 

Silver  . 

5.50      " 

Silver  .      .        8.50      " 

Silver   .      .      12.50      " 

Zinc 

3.00      " 

Zinc      .      .        4.00      " 

Zinc      .      .        5.00      " 

Zmc,  like  copper,  lowers  the  melting-point  and  hardens  the  gold. 
The  latter,  however,  seems  to  be  the  principal  reason  for  the  use  of 
zinc  in  solders,  for  the  former  could  be  obtained  with  copper.  Zinc 
also  controls  the  color  to  some  extent. 

The  formulae  of  the  solders  given  are  correct  for  one  manufacturer's 
product  only.  There  are  variations  in  the  quantities  of  gold  used  by 
the  different  manufacturers.  Some  of  them  may  reduce  the  quantity 
of  gold  for  the  purpose  of  reducing  the  melting-point,  some  may  want- 
to  vary  the  color  somewhat  and  some  undoubtedly  pursue  this  practice 
to  lessen  the  cost  of  production  of  the  solder.  The  following  table 
shows  the  advertised  fineness  of  three  manufacturers'  solders: 


1 

Carat. 

Fineness. 

Carat. 

2 

Fineness. 

Carat. 

3 

Fineness 

22 

750 

22 

802 

22 

830 

20 

729 

20 

735 

20 

708 

18 

6661 

18 

656 

18 

615 

The  variations  in  the  amount  of  gold  used  are  likely  to  cause  varia- 
tions in  the  color  of  the  solder  and  appreciable  differences  in  the  melting- 
points.  It  is  generally  safer,  therefore,  to  use  the  same  make  of  solder 
as  the  plate. 

Platinum  and  palladium  are  used  with  copper  and  silver  to  alloy 
gold  to  produce  hard  and  elastic  alloys  known  as  clasp  metals.  The 
following  formulae  represent  two  well-known  clasp  metals  in  the 
market : 


Gold     .      . 

64.  00  per  cent. 

Gold     .      .      . 

.      63.25  per  cent 

Platinum  . 

11.00 

Platinum  . 

.      10.00 

Palladium 

16.50 

Silver  . 

.      19.35 

Silver  . 

1.50 

Copper 

7.40 

Copper 

7.00 

Other  alloys  containing  gold,  platinum,  palladium,  silver  and  copper 
have  been  recently  introduced  as  desirable  for  casting  fillings,  crowns, 
etc.  This  class  of  alloys  usually  contains  not  less  than  80  per  cent,  of 
gold,  from  6  per  cent,  to  10  per  cent,  of  platinum,  about  2  per  cent,  of 


NATURE  OF  AMALGAM  349 

palladium,  0.05  per  cent,  to  2  per  cent,  of  silver  and  2  per  cent,  to  9 
per  cent,  of  copper.  This  class  of  alloys  generally  has  lower  melting- 
points  than  either  platinum  or  pure  gold.  They  are  said  to  be  more 
fluid  when  melted  and  as  a  result  enable  the  mold  to  be  filled  more 
perfectly  than  with  other  alloys. 

NATURE  OF  AMALGAM. 

An  amalgam  is  a  combination  of  two  or  more  metals,  one  of  which 
is  mercury,  and  may  be  either  a  liquid,  solid  or  semi-solid.  The  term 
amalgam  is  derived  from  the  Greek  malagma,  from  mallasso,  to  soften, 
the  presence  of  mercury  lowering  the  melting-point  of  such  a  mixture. 

The  term  metal  indicates  a  certain  number  of  chemical  elements 
which  in  the  present  state  of  chemical  science  are  undecomposable 
and  possess  certain  well-defined  characters  in  common,  such  as  opacity, 
luster,  conductivity,  high  specific  gravity  and  plasticity  or  capability 
of  being  drawn,  squeezed  or  hammered  without  loss  of  continuity.. 

Comparatively  few  of  the  metals  possess  characters  such  as  render 
them  suitable  to  be  employed  alone  by  manufacturers,  although  there 
are  many  applications  for  most  of  them  when  two  or  more  are  caused 
to  unite  permanently.  The  compound  thus  formed  by  the  union  of 
two  or  more  metals  is  termed  an  alloy.  The  word  alloy  is  believed 
to  have  been  derived  from  the  French  aloi  (the  metal  of  the  standard 
coin),  a  contraction  of  a  la  loi  (according  to  law).  Aa  amalgam,  then, 
represents  that  class  of  alloys  which  contain  mercury:  the  agencies 
by  which  the  union  of  metals  is  efi^ected  are  heat,  electro-deposition, 
pressure  at  ordinary  temperatures  and  the  dissolving  of  one  or  more 
metals  which  exist  in  a  solid  state  at  ordinary  temperatures  in  a  metal 
which  exists  in  a  liquid  state  at  ordinary  temperatures. 

Practically  all  alloys,  except  dental  amalgam  alloys,  are  formed 
through  the  agency  of  heat,  but  certain  soft  metals,  such  as  lead,  tin, 
bismuth,  cadmium,  etc.,  have  been  shown  by  Professor  Spring,  of 
Liege,  to  form  true  alloys  under  pressure  and  absence  of  heat.  This 
process,  however,  has  not  as  yet  found  application  much  beyond  the 
laboratories,  where  it  is  used  to  demonstrate  that  there  is  actual 
union  between  the  particles  of  different  metals  in  the  cold  when  they 
are  brought  into  intimate  contact.  Certain  alloys,  such  as  gold  and 
copper,  or  copper  and  zinc,  may  be  prepared  by  electro-deposition. 
Several  alloys  are  prepared  by  this  method  on  a  large  scale. 

The  utility  of  dental  amalgam  alloys  depends  largely  upon  the 
property  which  mercury  has  of  dissolving  most  other  metals  to  the 
point  of  saturation,  forming  alloys  which,  when  allowed  to  stand  for 
some  time,  harden  or  set.    This  hardening  or  setting  process  is  probably 


350  PROPERTIES  OF  FILLING  MATERIALS 

due  to  the  formation  of  a  chemical  compound  between  the  mercury 
and  one  or  more  of  the  metals  used  in  combination  with  it.  The  mass 
thus  formed  of  metal  or  alloy  in  combination  with  mercury  cannot  be 
regarded,  however,  as  a  true  amalgam,  for  Matthiessen  has  pointed  out 
that  such  a  mixture  may  be  either  a  chemical  compound,  a  solidified 
solution  or  a  mixture  of  all  three. 

There  are  some  phenomena,  such  as  change  in  volume,  change  in 
strength  and  evolution  of  heat  that  lead  to  the  belief  that  definite 
compounds  do  exist  in  definite  proportions  by  weight.  Most  of  the 
metals  used  to  form  the  alloy  which  is  combined  with  mercury  to  form 
an  amalgam  are  capable  of  existing  in  a  state  of  chemical  combination, 
although  they  are  subject  to  Matthiessen's  classification,  and  are 
usually  united  by  feeble  affinities,  for  it  is  necessary,  in  order  to  produce 
energetic  union,  that  the  constituents  exhibit  much  dissimilarity  in 
properties.  There  is  little  doubt  that  some  of  these  metals  do  unite 
in  definite  proportions,  although  it  is  difficult  to  obtain  them  as  such 
since  the  compounds  thus  formed  dissolve  in  all  proportions  in  the 
melted  metals  from  which  they  do  not  differ  very  Widel}^  in  their 
melting-points.  For  these  reasons  it  has  been  questioned  whether  not 
only  amalgams,  but  any  alloy  were  a  true  chemical  compound. 

Definite  compounds  have  been  proved  to  exist,  however,  in  both 
the  native  and  artificial  states.  Hiorns^  has  given  a  good  illustration  of 
a  chemical  compound  between  two  metals  in  the  alloy  of  copper  and 
tin  which  may  be  represented  by  the  formula  SnCu2,  containing  38.4 
parts  of  tin  and  61.6  parts  of  copper.  A  well-known  native  chemical 
compound  of  two  metals  is  represented  by  silver  and  mercury,  which 
are  found  crystallized  together  in  the  following  proportions:  (Ag2Hg2 
or  Ag2Hg6)  and  (Ag2Hg6) .    Many  other  examples  may  be  given. 

Under  the  term  solution  of  one  metal  in  another  we  understand  one 
like  ether  and  alcohol,  or  any  two  substances  which  may  be  mixed  in 
all  proportions  and  will  not  separate  into  layers  by  standing.  Solidified 
solution  would  indicate  the  solidification  of  a  perfectly  homogeneous 
diffusion  of  one  body  in  another  and  has  been  represented  by  glass, 
which  is  formed  in  the  liquid  state  at  a  high  temperature  and  solidified 
on  cooling  without  separation  of  the  different  silicates.  Hiorns  quotes 
Mendeleef  as  saying  that  solutions  are  fluid,  unstable,  definite  chemical 
compounds  in  a  state  of  dissociation,  and  that  of  such  a  kind  are  most 
metallic  alloys.  They  have  been  considered  in  the  Journal  of  the 
Chemical  Society  as  solidified  solutions  of  metals  which  contain  definite 
compounds  in  excess  of  one  of  the  constituent  metals.  The  subject  of 
solution  apparently  has  a  most  important  application  in  the  production 
pf  dental  amalgams. 

1  Mixed  Metals  qr  M^tallig  Alloys, 


NATURE  OF  AMALGAM  351 

In  the  same  manner  that  water  dissolves  saHne  substances,  alcohol 
dissolves  resins,  ether  dissolves  fats,  etc.,  mercury  dissolves  most 
metals.  A  very  interesting  phenomenon  to  observe  in  this  connection 
is  the  manner  in  which  most  solvents  act  upon  solids  (Hiorns.)  As  a 
rule  the  dissolving  power  of  each  liquid  is  confined  to  a  certain  class  of 
solids.  It  is  also  a  general  rule  that  the  solubility  of  a  body  in  any 
medium  depends  upon  a  similarity  in  the  constitution  of  the  body  and 
the  solvent. 

When  a  liquid  has  dissolved  all  of  a  solid  that  it  is  capable  of  retaining 
at  a  given  temperature  it  is  said  to  have  become  saturated;  but  even 
if  it  be  saturated  with  one  solid  it  may  yet  take  up  another,  and  often- 
times that  solvent  power  is  thereby  increased. 

A  general  survey  of  the  literature  reveals  quite  a  lack  of  knowledge 
of  the  peculiarity  of  solidified  solutions  and  appears  to  explain  to  some 
extent  why  there  has  been  so  much  misunderstanding  connected  with 
the  use  of  amalgam.  While  it  appears  important  that  the  subjects  of 
solutions,  crystallization  and  diffusion  should  be  considered  in  con- 
nection with  the  formation  of  dental  amalgams,  it  does  not  seem  pos- 
sible to  make  anything  but  general  statements  from  the  data  available. 

It  seems  to  be  generally  accepted  that  when  one  or  more  metals 
combine  with  mercury  to  form  a  dental  amalgam,  when  the  mass  sub- 
sequently sets  and  the  final  complete  diffusion  takes  place  the  same 
agencies  control  ordinary  chemical  phenomena.  External  heat,  for 
example,  influences  these  phenomena^  to  a  marked  degree  in  some 
instances,  it  being  considered  that  a  rise  in  temperature  of  10°  C.  will 
double  the  velocity  of  most  chemical  reactions.  The  conversion  of 
chemical  energy  into  heat  may  also  influence  these  phenomena.  The 
condition  of  contact  between  the  mercury  and  metal  or  alloy  will 
likewise  have  its  influence  upon  these  phenomena.^  Internal  move- 
ments of  the  component  parts  of  the  mass  may  facilitate  diffusion, 
solution  and  chemical  reactions.  Vibration,  in  some  cases,  will  do  the 
same.  In  fact,  about  the  only  difference  that  appears  between  dental 
amalgams  and  most  chemical  reactions  in  regard  to  controlling  factors 
is  that  the  metals  are  united  by  feeble  affinities,  and  there  exists  a 
tendency  for  the  amalgam  to  possess  the  properties  of  the  constituents. 
There  are  some  cases  where  a  combination  is  totally  difterent  from 
either  constituent  but  the  general  effect  is  for  each  constituent  metal 
to  maintain  its  identity.  Oftentimes  two  metals  with  like  physical 
properties  may  be  combined  to  produce  a  whole  series  of  alloys  which 
have  the  same  properties  as  the  constituent  metals.     On  the  other 

1  Arthur  W.  Gray,  Director  of  the  Caulk  Physical  Research  Laboratory,  Journal 
National  Dental  Assn.,  1919,  and  Transactioua  q(  th.^  Affierican  Institute  of  Mining 
Engineers,  1918, 

«  Xbid. 


352  PROPERTIES  OF  FILLING  MATERIALS 

hand,  if  two  metals  with  dissimilar  physical  properties  be  combined, 
the  result  may  be  a  product  quite  different  from  either  constituent 
depending  upon  the  nature  and  arrangement  of  the  eutectic. 

The  advantage  in  alloying  metals,  therefore,  seems  to  be  to  assemble 
in  one  compound  a  number  of  properties  which  cannot  be  found  in  one 
metal. 

Through  the  work  of  Flagg  and  Black,  silver,  tin,  copper,  zinc,  and 
occasionally  gold  in  small  quantities  have  been  found  to  possess  more 
desirable  and  less  undesirable  properties  than  any  other  equal  number 
of  metals.  Since  the  work  of  Dr.  Black^  two  new  but  distinct  classes 
of  alloys  have  appeared  as  the  principal  products  of  nearly  all  leading 
manufacturers.  One  of  them  contains  from  65  to  68  per  cent,  of 
silver,  26  to  28  per  cent,  of  tin,  3  to  5  per  cent,  of  copper,  and  |  to  2 
per  cent,  of  zinc.  The  other  contains  from  43  to  48  per  cent,  of  silver, 
48  to  58  per  cent,  of  tin,  and  1  to  2  per  cent,  of  zinc.  The  first  class 
is  known  as  high  percentage  silver  alloys,  quick  setting  alloys,  and 
Black's  alloys,  the  three  names  being  synonymous.  The  second  class 
is  known  as  low  percentage  silver  alloys,  slow  setting  alloys,  and  plastic 
alloys.  Both  classes  seem  to  have  grown  out  of  Black's  work,  the 
latter  class  undoubtedly  to  the  detriment  of  dentistry. 

The  first  class  seems  to  be  based  upon  the  properties  of  72|  per  cent, 
of  silver  and  27|  per  cent,  of  tin,  the  most  important  of  which  is  the 
small  amount  of  shrinkage  which  takes  place  when  this  alloy  is  con- 
verted into  amalgam.  The  second  class  seems  to  be  based  upon  the 
dual  movement  of  50  per  cent,  of  silver  and  50  per  cent,  of  tin,  which, 
by  referring  to  Dr.  Black's^  charts  is  seen  to  be  about  2  points.  Besides 
the  two  principal  classes  of  alloys  mentioned,  there  are  in  the  market 
many  of  the  alloys  made  and  used  previous  to  Dr.  Black's  work  in 
1895-1896. 

Townsend's  original  alloy  of  silver  42  per  cent,  and  tin  58  per  cent. 
is  still  used  by  some. 

Flagg' s  alloys,  especially  the  one  containing  silver  60  per  cent.,  tin 
35  per  cent,  and  copper  5  per  cent.,  are  still  in  the  market  and  used  by 
some. 

There  are  a  dozen  or  more  alloys  made  to  supply  the  varied  demands 
of  the  profession.  Some  of  them  have  one  or  more  prominent  qualities, 
but,  as  a  rule,  they  are  not  free  from  a  reduction  in  volume  at  the 
time  of  and  subsequent  to  insertion,  nor  do  they  seem  to  be  based  upon 
any  particular  principle,  as  are  the  two  classes  which  have  resulted 
from  Black's  work.  Inasmuch  as  these  alloys  are  also  composed  of 
silver,  tin,  copper  and  zinc,  they  are  subject  to  the  same  consideration 

1  Dental  Cosmos,  1895-1896.  2  jbid. 


NATURE  OF  AMALGAM  353 

as  far  as  physical  and  chemical  properties  are  concerned.  It  would 
seem  that  dental  amalgams  are  best  understood  by  dividing  them  into 
the  two  classes  spoken  of  as  high  percentage  silver  alloys  and  low  per- 
centage silver  alloys.  The  difference  between  the  two  can  probably 
be  best  represented  by  first  considering  the  most  important  properties 
of  each  constituent. 

Silver  unites  with  mercury  in  definite  proportions,  and  through  its 
comparatively  strong  aflfinity  for  mercury  and  its  large  proportions  it 
largely  controls  the  setting.  It  tarnishes  quite  readily  in  sulphuretted 
hydrogen  and  soluble  sulphids.  It  increases  in  volume  when  amal- 
gamated. It  increases  edge  strength,  lessens  the  fiow  and  because  of 
its  great  tendency  to  crystallize  and  its  property  of  going  into  solu- 
tion in  mercury  slowly  at  ordinary  temperatures  it  causes  the  alloy  to 
amalgamate  tardily  and  the  mass  to  work  hard. 

Tin  unites  with  mercury  in  all  proportions  at  all  temperatures, 
forming  a  weak  crystalline  compound.  It  retards  the  setting,  decreases 
in  volume  when  amalgamated,  decreases  edge  strength,  increases  the 
flow,  and  imparts  plasticity,  thus  causing  the  mass  to  work  easily. 

Copper  unites  with  mercury  with  difficulty  at  ordinary  temperatures, 
although  in  definite  proportions  it  generally  hastens  the  setting, 
increases  edge  strength,  lessens  flow,  does  not  change  appreciably  in 
volume  when  amalgamated  and  is  easily  tarnished  by  sulphuretted 
hydrogen  and  soluble  sulphids. 

Zinc  unites  with  mercury  easily  and  in  definite  proportions,  increases 
in  volume  when  amalgamated,  hastens  the  setting,  increases  edge 
strength,  lessens  flow,  improves  color  and  imparts  a  peculiar  smooth- 
ness to  the  mass  during  amalgamation. 

Gold  when  melted  with  the  other  constituents,  as  most  of  the 
present  alloys  are  made,  adds  almost  no  desirable  properties  and  adds 
one  or  two  undesirable  properties.  It  adds  a  little  to  the  color  and 
makes  a  very  tough  amalgam,  but  imparts  a  peculiar  pasty  springi- 
ness which  makes  it  difficult  to  pack.  There  are  some  possibilities  in 
the  use  of  gold  in  small  quantities,  however,  that  are  not  fully  developed 
and  which  may  lead  to  a  more  general  use  of  this  metal. 

From  the  nature  of  metallic  alloys  we  may  assume  that  certain 
proportions  of  these  constituents  enter  into  combination  and  other 
portions  are  simply  in  a  state  of  mixture  or  solution.  From  the  similar- 
ity of  the  metals  we  may  assume  that  energetic  union  has  not  taken 
place,  and,  as  a  result,  the  portions  united  chemically  are  not  expected 
to  have  properties  diverging  widely  from  their  constituents. 

Since  solutions  and  mixtures  generally  possess  the  properties  of 
their  constituents,  we  would  expect  a  compound  of  these  metals  to  be 
quite  largely  the  sum  of  the  properties  of  its  constituents.  Such  seems 
23 


354 


PROPERTIES  OF  FILLING  MATERIALS 


to  be  the  case  with  these  alloys.  A  point  to  be  observed  in  the  con- 
sideration of  these  alloys  is  that  one  or  two  metals  are  used  as  the  base 
of  the  alloy  and  the  others  as  modifiers,  the  attempt  being  made  to 
add  to  the  properties  of  the  basal  constituents  some  of  the  properties 
of  other  constituents. 

A  consideration  of  the  alloys  now  in  use,  with  one  or  two  exceptions 
shows  that  the  selection  of  these  metals  and  the  proportions  of  each 
have  been  made  with  reference  to  their  physical  behavior,  special 
emphasis  being  placed  upon  changes  in  volume,  color  and  strength. 
Fenchel,^  however,  has  studied  amalgams  from  a  different  point  of  view. 
He  has  taken  a  break  in  the  cooling  curve  of  any  liquid  (including 
melted  metals)  to  indicate  a  change  in  physical  constitution,  and  from 
this  traced  the  crystallizing  curve  of  some  of  these  alloys  in  increasing 
proportions  to  each  other.  He  has  studied  the  structure  of  these 
alloys  microscopically  as  well  as  with  reference  to  alteration  in  form, 
resistance  to  stress,  specific  gravity  and  electromotive  force  of  currents 
set  up  in  the  mouth  by  different  metals,  all  of  which  form  a  very  valu- 
able part  of  scientific  literature.  Fenchel's  work  may  be  said  to  follow, 
more  closely  the  chemical  phases  of  alloys  than  the  physical  ones, 
while  the  work  of  others  seems  to  be  devoted  largely  to  the  physical 
properties. 


A  B  c  D  E  F 

Fig.  339. — Test  cylinders  of  amalgam  prepared  by  amalgamating  6  gm.  alloy.  Cylin- 
ders A  and  B  from  low-silver  alloy  compress  and  crack.  Cylinders  C,  D,  E,  and  F  from 
high-silver  alloy  burst  explosively.  Cylinders  B  and  D,  both  packed  under  400  kg.  show 
difference  in  size  of  amalgam  from  same  weight  of  alloy.  D  is  25  per  cent,  larger  and 
75  per  cent,  stronger  than  B.  C,  D,  and  E  are  packed  under  141,  400,  and  1131  kg. 
per  cir.  cm.  respectively.     Natural  size  10  mm.  in  diameter. 


It  would  appear  that  a  clear  understanding  of  the  physical  behavior 
of  these  alloys  cannot  be  had  without  at  least  a  working  knowledge 
of  their  chemical  behavior.  For  the  present,  however,  our  knowledge 
of  alloys  (the  two  classes  mentioned)  is  confined  largely  to  their 
physical  behavior.  The  principal  difference  between  the  two  classes 
of  alloys  should  be  obvious.  The  first,  with  more  silver,  less  tin  and 
some  copper  is  stronger,  more  stable  in  form,  more  free  from  decrease 
in  volume,  though  it  works  hard  and  sets  quickly.    The  second,  with 

1  Fgr  a  gtudv  of  Fenchel's  work  see  his  various  papers  in  the  D^n^al  CpsmQs, 


NATURE  OF  AMALGAM 


355 


3000 


y  4000 
O  h 

K  2 

np 
i_  z 

V?  uJ 
^  O 

tB  < 

5^ 

>::  £ 

O  c  2000 

2  y 
X  Q. 
^o 

Z    1000 


/^ 

-• ■ 

• 

- 

?5— 

HIGH 
SILVER 


LOW 
SILVER 


0  10  20 

AGE  OF  AMALGAM  IN  DAYS 


30 


40 


4000 


UJ 

in  2 

L.     U 

<  :;!  3000 

Z  3 

lU  U 

!o  o 

,3  c  2000 

z  u 
X  Q- 

§3 

z  1000 


•  

yf-H ^ 

i  __^        "i  I*  T 


HIGH 
SILVER 


LOW 
SILVER 


0  2  4 

AGE  OF  AMALGAM  IN  HOURS 


Fig.  340.- 


-Hardening  of  amalgams.     Amalgam  from  high-silver  alloy  is  75  per  cent, 
stronger  than  that  from  low-silver  fjUoy. 


356  PROPERTIES  OF  FILLING  MATERIALS 

its  high  percentage  of  tin,  low  percentage  of  silver  and  absence  of 
copper  is  easier  to  amalgamate,  sets  slower,  is  weaker  and  is  a  little 
lighter  in  color  (Figs.  339  and  340). ^^ 

These  two  classes  of  alloys  resemble  some  of  the  older  as  well  as 
many  of  the  newer  ones  by  having  some  properties  in  common. 

Contraction  and  expansion,  for  example,  seem  to  be  phenomena 
accompanying  the  setting  of  all  dental  amalgams.  Pioneer  workers 
seem  to  have  attributed  these  properties  to  the  composition  of  the 
alloy.  Later  work  showed  that  annealing  the  cut  alloy  had  a  marked 
influence  upon  change  in  volume.  The  most  recent  work  has  furnished 
additional  evidence  to  substantiate  the  claims  of  the  author  in  a 
former  edition  of  this  book  that  other  things  than  composition  and 
annealing  of  the  cut  alloy  had  their  influence  upon  the  phenomena 
accompanying  the  setting  of  dental  amalgams. 

The  thoroughness  with  which  this  recent  work  has  been  done  seems 
to  have  proved,  beyond  doubt,  that  many  of  the  same  factors  which 
control  the  behavior  of  other  alloys  control  dental  amalgams.  Promi- 
nent among  such  factors  are:  packing  pressure,  packing  time,  tri- 
turation time,  mercury  alloy  ratio,  size  of  the  alloy  particles,  tem- 
perature at  which  the  dental  amalgam  is  kept  and  age  of  the  amalgam. 
On  account  of  the  acknowledged  inferiority  of  the  low  percentage 
silver  alloys  little  or  no  data  will  be  presented  to  show  their  behavior, 
it  being  assumed  that  a  modern  high-grade  practice  cannot  be  con- 
ducted by  the  use  of  these  materials.  What  follows,  therefore,  has 
special  reference  to  the  high  percentage  silver  alloys  (Figs.  341  and 
342)  .3  4 

It  may  be  seen  that  the  curves  (Fig.  342  and  curve  180,  Fig.  341) 
agree  in  a  general  way  with  respect  to  the  changes  in  volume  that 
take  place  at  the  time  and  subsequent  to  the  combination  of  the 
mercury  and  alloy  in  a  high  percentage  silver  amalgam.  There  appears 
to  be  a  contraction  at  the  time  and  immediately  after  the  combination 
of  mercury  and  alloy  has  taken  place,  which  is  followed  by  a  slow 
expansion.  This  is  followed  by  a  still  slower  contraction  which,  if  the 
alloy  be  properly  made,  brings  the  volume  of  the  amalgam  to  approxi- 
mately the  point  of  beginning.  Earlier  workers  have  failed  to  note  the 
first  movement  of  dental  amalgams  on  account  of  the  use  of  instru- 
ments not  suitable  for  this  work,  and  have,  in  many  instances,  failed 
to  detect  the  final  slow  contraction. 

This  manner  of  manipulation  to  produce  this  typical  reaction  curve 
is  described  under  the  chapter  on  Manipulation  of  Amalgams,  with 
the  possible  exception  of  the  pressure  used  in  packing.  In  Fig.  341, 
curve  No.  180  was  packed  with  100  kg.  per  circular  centimeter.  No. 

1  Arthur  W.  Gray.  2  jbid.  s  Ibid. 

^  Souder  and  Peters:    Dental  Cosmos,  March,  1920. 


NATURE  OF  AMALGAM 


357 


178  with  400  kg.  per  circular  centimeter  and  No.  181  with  1600  kg. 
per  circular  centimeter.  It  remains  to  be  proved  that  the  pressure 
used  in  the  production  of  the  typical  reaction  curves  is  not  more  than 


0.05 

<^ 

><-^ 

RI80 

. 

0 

— 

^ 

"^^ 

^---- 

R178 

j^^^^ 

J 

0,05 

RI8I 

0  2  4  6  8 

AGE  OF  AMALGAM  IN  HOURS 

Fig.  341. — Typical  reaction  expansion  curve  (R180)  and  modifications  caused  by 
increase  of  packing  pressure. 

is  used  in  practice  if  the  movements  represented  by  these  curves  are 
to  be  taken  as  indicative  of  what  takes  place  in  practice.  There  seems 
to  be  no  doubt  but  that  they  are  quite  accurate  and  furnish  a  valuable 
lesson  for  those  who  have  been  inclined  to  ignore  the  packing  pressure 
as  a  factor  in  modifying  the  behavior  of  dental  amalgams.    It  may 


V 

^ 

^-f~- 

^ 

^ 

/?-/ 

il-e 

t.sc 

/i 

f 

,v*^ 

:::::- 

^_ 

_^ 

— 

S■^ 

Zl'l 

t  t< 

/ 

/ 

— - 

'"' 

A. 

— i^ 

fiSA. 

f 

/ 

6-4 

H-c 

tl.CC 

V 

^      s      J      4      s      e       7      e       5      w      //     la     ij     /-f     /s 
Fig.  342. — Setting  changes  in  amalgam  maintained  at  nearly  the  same  temperature. 


be  noted  that  in  curve  No.  178,  where  the  packing  pressure  was  raised 
from  100  kg.  to  400  kg.  there  is  no  initial  contraction  shown,  for  the 
reason  that  the  increase  in  the  pressure  has  hastened  the  reaction  to 


358 


PROPERTIES  OF  FILLING  MATERIALS 


such  an  extent  that  this  movement  has  taken  place  before  it  could  be 
detected  or  possibly  during  the  mixing  of  the  alloy  and  mercury. 
Curve  No.  181  shows  the  slow  expansion  that  we  formerly  thought 
took  place  in  an  hour  or  two  to  have  taken  place  during  the  first  few 
minutes,  due  to  a  further  increase  in  the  packing  pressure  from  400  kg. 


0.20 


0.15 


0.10 


0.05 


0.05 


0.10 


R58 

> 

^ 

^ 

y 

> 

^ 

^ 

// 

""^ 

\ 

"^^ 

R59 

V 

\ 

\ 

^ 

R66 

- 

age:  of  amalgam  in  hours 

Fig.  343. — Effects  of  changing  size  of^alloy  particles. 


to  1600  kg.  and  consequently  a  further  hastening  of  the  setting.  While 
it  is  true  there  is  less  mercury  retained  in  a  mass  of  amalgam  (Fig.  343) 
as  the  pressure  is  raised,  these  and  other  data  that  are  available  appear 
to  show  that  increases  in  pressure  hasten  the  reaction  between  alloy 
and  mercury  and,  as  a  result,  change  the  reaction  curve  of  volume 
change.  This  should  be  expected,  for  it  is  well  known  that  as  com- 
bining substances  are  brought  into  more  intimate  contact  the  more 
rapid  will  be  the  reaction. 

It  has  recently  been  demonstrated  that  continuing  the  pressure 
longer  than  usual  will  produce  somewhat  the  same  result  as  increasing 
the  pressure,  though  undoubtedly  to  a  less  extent.  Increasing  the 
trituration  time  (see  Mixing  Alloys)  of  alloy  and  mercury  also  has  to 


MATURE  OF  AMALGAM  350 

do  with  condition  of  contact  and  has  been  demonstrated  to  accelerate 
the  reaction  of  the  alloy  and  mercury  up  to  a  certain  point  where 
setting  begins.  This  will  likewise  change  the  reaction  curve.  In  a 
similar  manner  the  rate  of  reaction  may  be  modified  by  varying  the 
percentages  of  mercury  and  alloy  for  this,  too,  may  modify  the  con- 
dition of  contact. 

Still  further  data  on  modification  of  the  reaction  curve  by  varying 
the  condition  of  contact  between  the  reacting  substances  are  con- 
tained in  Fig.  343,^  which  shows  the  results  of  amalgamating  three 
different  sizes  of  alloy  particles. 

Curve  R58  represents  the  reaction  that  took  place  from  the  use  of 
alloy  particles  that  were  too  coarse  to  pass  through  a  sieve  of  48  meshes 
to  the  inch.  Curve  R59  shows  the  reaction  when  alloy  particles  that 
would  pass  through  a  sieve  200  meshes  to  the  inch  were  used  and  R66 
when  still  finer  particles  were  used.  By  comparing  these  curves  with 
the  typical  reaction  curves  (Figs.  341  and  342)  it  may  be  seen  that  as 
the  alloy  particles  were  made  progressively  finer  the  reaction  was 
accelerated  and  characteristic  features  appeared  earlier  and  more 
prominently. 

It  is  well  knowTQ  that  as  heat  is  increased,  molecular  activity  is  also 
increased,  resulting  in  accelerated  chemical  reactions  and  increased 
solubility  of  some  substances  for  others.  Not  until  recently, 
however,  has  this  been  recognized  as  having  its  influence  upon  the 
reaction  between  mercury  and  alloys  with  which  to  produce  dental 
amalgams.  It  does  not  appear  that  the  temperature  of  amalgam 
fillings  inserted  by  the  dentist  can  be  detected  and  controlled,  hence 
this  factor  in  volume  change  is  not  of  special  interest  to  him.  Those 
who  are  doing  experimental  work,  such  as  comparing  different  products 
with  delicate  instruments  for  detecting  changes  in  volume,  may  observe 
marked  differences  in  the  reactions  that  will  take  place  at  freezing 
temperatures  and  temperature  of  the  body. 

It  has  not  been  customary  for  those  familiar  with  the  behavior  of 
dental  amalgams  to  mention  the  age  of  the  amalgam  when  descriptions 
of  changes  in  volume  were  given.  Notwithstanding  this  custom  it 
has  been  known  for  many  years  that  amalgams  changed  in  volume 
and  that  this  change  in  volume  did  not  all  take  place  suddenly.  By 
referring  to  Fig.  341 ,  it  may  be  seen  that  Gray  shows  changes  in  volume 
at  the  end  of  seven  hours  and  Souder  and  Peters  (Fig.  342)  show 
changes  at  the  end  of  twenty-five  hours.  The  author  has  repeatedly 
found  these  changes  to  continue  over  a  period  of  several  months  when 
the  amalgam  was  packed  with  hand-pressure  and  the  mass  has  been 
incompletely  mixed,  as  is  often  done  in  practice.     If,  therefore,  the 

1  Gray,  Arthur  W. 


360  PROPERTIES  OF  FILLING  MATERIALS 

amount  of  volume  change  that  accompanies  the  setting  of  these  amal- 
gams is  to  be  given,  the  age  should  also  be  given,  for  it  is  of  little  value 
to  know  that  an  amalgam  expands  or  contracts  a  certain  number  of 
points  unless  it  is  known  whether  the  figures  represent  the  total  volume 
change  or  only  a  portion  of  it. 

From  the  foregoing  it  seems  established  that  there  are  several  ways 
that  one  who  makes  a  dental  amalgam  filling  may  vary  its  volume 
change.  The  two  factors  of  most  importance,  however,  are  compo- 
sition and  the  annealing  of  the  cut  alloy,  both  of  which  are  under  the 
control  of  the  manufacturer  of  these  products,  the  former  entirely  and 
the  latter  to  a  marked  degree.    / 

With  Flagg's  work  as  a  basis,  Black  seems  to  have  established  suffi- 
ciently accurately  for  practical  purposes  the  contraction  and  expansion 
ranges  for  the  metals  that  appear  most  suitable  for  the  production  of 
alloys  for  making  dental  amalgams.  He  assumed  that  of  the  properties 
which  amalgams  possess,  nothing  was  of  as  much  importance  as  free- 
dom from  contraction.  He  regarded  it  as  imperative  that  there  must 
be  absolute  freedom  from  contraction  and  only  a  minimum  of  expan-- 
sion.  With  this  view  of  the  situation  he  constructed  more  accurate 
instruments  than  had  been  used  previously  and  made  numerous 
experiments  to  determine  not  only  the  metals  but  the  proportions 
which  would  yield  such  an  amalgam  as  the  one  referred  to. 

He  concluded  that  an  amalgam  could  be  made  that  would  lie  abso- 
lutely still  while  hardening.  Later  workers,^  -  ^  with  more  delicate 
instruments  than  those  used  by  Black,  seem  to  have  demonstrated 
(Figs.  341  and  342)  that  none  of  the  amalgams  now  in  use  are  entirely 
free  from  change  in  volume. 

In  describing  his  experiments.  Black"*  stated  that  a  fixed  formula 
was  not  good  for  general  use  on  account  of  inability  to  get  metals 
which  are  chemically  pm-e  at  a  price  that  was  permissible  for  the 
production  of  these  alloys  for  amalgams.  He  and  those  who  followed 
his  teachings  clakaed  that  a  general  formula  might  be  adopted  for  a 
given  batch  of  metals,  and  then  it  was  necessary  to  experiment  with 
this  batch  of  metals  by  varying  this  general  formula  in  order  to  get  a 
product  that  would  lie  still. 

Some  reputable  manufacturers  declined  to  accept  this  view  and 
claimed  their  products  were  made  from  fixed  formulae.  Inasmuch  as 
the  claims  of  the  adherents  to  a  fixed  formula  have  not  been  disproved 
and  their  products  appear  to  show  the  same  behavior  as  the  products 
that  are  said  to  be  made  from  a  plan  instead  of  a  fixed  formula,  it 
appears  more  reasonable  to  believe  that  fixed  formulse  will  yield  given 
results  provided  the  technic  in  production  is  properly  controlled.    Since 

1  Souder  and  Peters.  ^  Gray,  Arthur  W. 

3  Ward,  Marcus  L. :  Dental  Cosmos.  *  Operative  Dentistry,  vol.  ii. 


NATURE  OF  AMALGAM  361 

nothing  has  been  written  by  Dr.  Black  or  his  followers  about  the 
manner  of  preparing  these  products  nor  the  character  of  the  impurities 
that  silver,  tin,  copper  and  zinc  are  said  to  contain,  it  appears  likely 
that  inability  to  produce  fixed  products  from  fixed  formulae  was  due 
to  inability  to  maintain  fixed  conditions  in  the  process  of  production, 
A  review  of  Fenchel's  work  and  the  earlier  work  of  Kirk  and  Burchard, 
each  of  whom  has  viewed  more  closely  the  chemical  phases  of  alloys, 
would  not  suggest  the  plan  offered  by  Black. 

The  question,  "  Why  does  a  fixed  formula  not  give  an  alloy  with  a 
definite  volume  change,"  has  been  asked  of  the  author  so  many  times 
by  teachers  and  practitioners  alike,  that  it  would  seem  that  the  plan 
suggested  by  Black  has  not  been  understood  nor  accepted  by  the 
profession.  All  seem  agreed,  however,  that  the  plan  gives  as  good 
results,  and  furnishes  the  profession  with  as  good  alloys,  as  our  present 
knowledge  of  the  subject  will  permit.  It  is  in  the  manner  of  reaching 
the  result  that  there  seems  to  be  a  difference  of  opinion.  The  plan 
implies  more  than  the  mere  assumption  that  impure  metals  will  not 
give  a  definite  change  in  volume.  It  implies  that  metals  cannot  be 
constantly  obtained  with  a  degree  of  impurity,  for  if  a  metal  contained 
a  certain  impurity  in  certain  quantities  every  time  it  was  purchased, 
allowance  could  be  made  for  it  in  the  formula. 

While,  as  a  rule,  native  metals  are  not  to  be  relied  upon,  there  are 
some  instances  in  which  impurity  can  be  determined  and  allowance 
made  for  it  comparatively  easily.  It  is  quite  sweeping  in  its  scope, 
however,  to  say  that  refined  metals  cannot  be  obtained  which  are 
quite  constant  in  their  impurities. 

The  author  made  analyses  of  three  high  percentage  silver  alloys 
within  the  last  year,  which  were,  in  his  opinion,  most  widely  used  and 
most  accurately  made,  with  a  view  of  further  confirming  his  opinion 
that  more  than  one  formula  will  give  practically  the  same  volume  of 
change  provided  the  formula  selected  lies  within  the  ranges  given  for  a 
high  percentage  silver  alloy.    They  are  as  follows: 

No.  1 

Silver 68 .  00  per  cent. 

Tin 26.00 

Copper 5.00  " 

Zinc .        1.00  " 

No.  2 

Silver 67.00 

Tin 27.00 

Copper 5.00 

Zinc 1.00 

No.  3 

Silver :. 67.00 

Tin 27.00 

Copper 5.00  " 

Zinc 1.00 


362  PROPERTIES  OP  PJLLlKG  MATERIALS 

By  comparing  these  analyses  with  the  many  pubhshed  formulae 
contained  in  dental  literature  it  may  be  seen  there  is  a  much  nearer 
uniformity  in  composition  than  existed  about  ten  years  ago.  Repeated 
analyses  of  the  first  alloy,  however,  have  shown  a  constant  tendency 
to  contain  more  silver  than  most  alloys  in  the  market,  though  the 
volume  change  seems  to  be  the  same  under  the  same  conditions  of 
manipulation. 

There  appears  to  be  one  thing  of  special  interest  in  the  three  analyses 
given,  namely,  the  uniform  use  of  zinc  in  small  quantities.  Within 
recent  years  a  very  few  manufacturers  have  eliminated  the  zinc  entirely, 
apparently  on  the  basis  of  some  of  the  last  words  from  Dr.  Black  on 
the  subject  of  amalgam,  which  seem  not  to  have  been  substantiated 
by  experimental  work.  Dr.  Black  stated  that  0.05  per  cent,  of  zinc 
was  not  desirable,  for  the  reason  that  amalgams  containing  it  would 
continue  to  change  in  volume  for  five  years  or  more.  Determinations 
for  zinc  in  alloys  for  amalgams  have  been  made  by  the  author  on 
several  of  the  best  products  now  in  use,  with  affirmative  results  in 
most  cases  showing  that  the  judgement  of  a  large  majority  of  the  manu- 
facturers is  in  favor  of  the  use  of  zinc  in  small  quantities,  in  order  that 
their  products  will  be  more  free  from  contraction  and  more  permanently 
light  in  color.  The  few  who  manufacture  so-called  high  percentage 
silver  alloys  without  any  zinc  are  not  known  to  possess  modern  instru- 
ments for  detecting  changes  in  volume,  nor  are  they  among  those 
who  have  published  anything  with  respect  to  the  effect  of  using  zinc 
in  alloys  except  that  Dr.  Black  advised  against  its  use  in  his  latter  days. 

Since  Dr.  Black  is  supposed  to  have  approved  of  the  use  of  zinc  in 
his  earlier  days  of  experimentation,  and  practically  all  of  the  best 
products  in  the  market  (the  high  percentage  silver  alloys)  have  been 
based  upon  its  use,  the  placing  in  the  market  of  the  same  alloys  without 
the  zinc  has  caused  some  controversy.  Both  participants  to  the  contro- 
versy claim  to  have  products  made  according  to  Black's  plans.  Those 
who  use  no  zinc  claim  to  have  a  product  that  is  more  free  from  expan- 
sion, while  those  using  the  zinc  claim  to  have  products  more  free 
from  contraction.  The  author  has  studied  this  problem  for  some  time 
and  has  had  hearty  cooperation  on  the  part  of  some  of  the  most  able 
manufacturers  as  well  as  advice  from  the  Bureau  of  Standards  on 
instruments  for  detecting  changes  in  volume.  As  these  studies  have 
proceeded  it  has  become  more  evident  that  if  an  alloy  for  a  dental 
amalgam  is  to  have  a  minimum  of  contraction  it  must  contain  from 
I  per  cent,  upward,  not  exceeding  2  per  cent,  of  zinc.  Reference  to  the 
analyses  given  shows  the  judgment  of  three  large,  reliable,  and,  in  the 
opinion  of  the  author,  most  capable  manufacturers,  which  is  that  about 
1  per  cent,  of  zinc  should  be  used. 


NATURE  OF  AMALGAM  303 

The  other  known  factor  in  changes  in  vohnne,  annealing  the  cut  alloy, 
is  of  special  interest  for  the  reason  that  to  a  small  degree  it  is  con- 
trolled by  the  dentist,  though  it  must  be  kept  in  mind  that  this  variable 
is  controlled  largely  by  the  manufacturer. 

Annealing  of  Alloys. — Dr.  J.  Foster  Flagg  seems  to  have  been  the 
first  to  call  attention  to  the  fact  that  alloys  which  were  freshly  cut 
behaved  differently  when  amalgamated  than  the  same  alloys  did  after 
they  had  stood  for  some  time.  Dr.  Black  traced  the  phenomenon 
through  a  great  number  of  experiments  and  finally  arrived  at  the 
conclusion  that  the  cut  alloy  is  hardened  by  the  violence  in  cutting, 
the  condition  thus  produced  being  analogous  to  the  condition  of  the 
same  metals  in  hammering.  His  earlier  observations  led  to  the  belief 
that  motion  brought  about  the  change,  but  later  experiments  showed 
that  it  had  no  influence.  Oxidation  was  thought  to  be  a  factor,  but 
was  finally  eliminated  as  one  of  the  causes.  After  a  great  many 
experiments  it  was  proved  that  the  change  was  produced  by  annealing 
or  tempering,  that  is,  a  molecular  alteration  of  the  cut  alloy.  The  tem- 
perature at  which  this  is  produced  ranges  from  room  temperature 
upward.  If  the  alloy  be  subjected  to  room  temperature  for  a  year  or 
more  the  same  effect  is  produced  as  when  it  is  subjected  to  a  higher 
temperature  for  a  shorter  time.  It  has  been  found  that  the  low  tem- 
perature and  longer  time  of  exposure  bring  about  a  more  complete 
annealing.  The  change  can  be  brought  about  by  subjecting  the  cut 
alloy  to  the  temperature  of  boiling  water  for  about  twenty  minutes, 
although  there  is  not  quite  the  same  quality  to  the  alloy  that  there  is 
when  it  is  subjected  to  a  temperature  of  120°  F.  for  from  two  days  to 
a  week.  The  amount  of  heat  required  to  bring  about  the  change  is  not 
the  same  for  all  alloys,  although  each  formula  seems  to  change  in  many 
of  its  properties  with  this  treatment.  That  the  property  of  these  alloys 
to  change  by  so-called  ageing  or  annealing  is  a  physical  phenomenon, 
has  been  the  opinion  of  Dr.  Black  and  of  Fenchel,^  but  whether  it  is 
caused  by  hardening  during  the  cutting  ptocess,  as  suggested  by  Dr. 
Black,  is  a  question  worthy  of  consideration  by  those  interested  in  the 
cause  of  this  peculiarity. 

It  is  well  known  that  the  working  of  metals  forces  their  molecules 
into  unnatural  positions,  and  that  by  annealing  they  are  largely  restored 
to  their  normal  state.  But  it  is  also  well  known  that  the  rate  and 
manner  of  cooling  of  many  metals  may  preserve  in  some  cases  and 
alter  in  others  the  mode  of  existence  of  the  molecules  at  the  time  they 
were  molten.  It  is  also  worthy  of  note  in  this  connection  that  unequal 
stresses  are  set  up  in  some  castings  by  cooling  the  outer  layers  of  the 

1  Dental  Cosmos. 


364  PROPERTIES  OF  FILLING  MATERIALS 

metal  much  more  quickly  than  the  interior,  thereby  causing  a  com- 
pression of  the  interior  by  the  outer  layers. 

By  annealing,  which  is  the  reverse  of  hardening,  the  metal  flows, 
and  this  tension  is  relieved.  The  effect  of  annealing  upon  changes  in 
volume  appears  to  reduce  the  amount  of  expansion  of  alloys  which 
expand  and  to  increase  the  contraction  of  those  which  contract.  Its 
effect  upon  the  strength  of  amalgam  seems  to  be  to  increase  the  strength 
of  those  which  set  very  quickly  up  to  a  certain  point,  after  which  it 
seems  to  decrease  the  strength  somewhat.  It  does  not  appear  to  have 
the  same  effect  upon  the  strength  of  amalgams  made  from  low  per- 
centages of  silver.  Whether  or  not  these  alloys  are  not  hardened  as 
much  in  their  production  cannot  be  said  definitely.  It  seems,  however, 
that  practically  all  alloys  for  amalgams  are  hardened  to  some  extent 
in  their  production  in  one  way  or  another  and  the  annealing  restores 
them  to  what  appears  to  be  their  natural  condition.  The  makers  of 
high  percentage  silver  alloys  for  amalgams  recognize  that  these  pro- 
ducts are  in  a  different  physical  condition  after  annealing,  and  as  a 
result  of  the  change  produced  by  the  annealing  arrange  the  formulae 
for  these  products  so  that  the  properties  desired  are  obtained  after  the 
annealing  has  taken  place.  This  procedure  is  necessary  for  the  reason 
that  annealing  of  these  alloys  takes  place  at  room  temperature  and 
upward.  If,  therefore,  the  change  that  takes  place  in  the  annealing  had 
not  been  provided  for  by  the  maker,  and  if  the  annealing  had  not  been 
given  to  the  alloy  by  the  maker,  the  practicing  dentist  would  very 
often  have  an  alloy  for  amalgam  that  would  vary  in  the  results  it 
would  give. 

Another  interesting  phenomenon  brought  out  by  annealing  is  reduc- 
tion in  the  percentage  of  mercury  required  to  make  a  plastic  mass  of 
alloy  and  mercury.  When  the  high  percentage  silver  alloys  are  freshly 
cut  they  set  so  quickly  that  it  is  almost  impossible  to  add  enough 
mercury  to  keep  the  mass  plastic  for  longer  than  a  very  few  seconds. 
As  annealing  takes  place  the  mass  sets  more  slowly  and  less  mercury 
is  required  to  make  the  mass  of  alloy  and  mercury  plastic.  As  much  as 
70  per  cent,  of  the  mass  of  alloy  and  mercury  must  be  mercury  before 
annealing  takes  place  if  the  alloy  used  be  a  high  percentage  one,  while 
after  the  same  alloy  has  been  fully  annealed  50  per  cent,  will  be 
sufficient. 

This  makes  four  ways  that  annealing  is  known  to  have  an  effect 
upon  the  final  result:  (1)  upon  change  in  volume;  (2)  upon  strength; 
(3)  upon  the  rate  of  setting;  (4)  upon  the  percentage  of  mercury  to 
make  a  plastic  mass. 

Some  of  the  makers  of  these  products  take  advantage  of  the  annealing 
to  control  the  rate  of  setting  and  place  upon  the  market  alloys  for 


NATURE  OF  AMALGAM  365 

amalgams  which  are  marked  rapid  setting,  medium  setting,  and  slow 
setting.  Present  knowledge  of  the  subject  leads  to  the  conclusion  that 
this  practice  is  not  likely  to  produce  the  best  result  for  the  reason  that 
annealing  also  controls,  to  some  extent,  volume  change.  It  appears 
more  likely  that  this  practice  is  followed  in  order  to  produce,  without 
adopting  the  other  alternative  of  altering  the  formula,  alloys  with 
different  rates  of  setting  for  those  who  want  the  mass  of  alloy  and 
mercury  to  set  quickly  enough  to  enable  it  to  be  polished  to  some 
extent  at  the  time  of  setting. 

Thermal  Expansion. — Until  very  recently  no  data  were  available 
to  show  the  relation  of  amalgam  to  other  materials  in  common  use  in 
dentistry  with  respect  to  the  expansion  that  takes  place  when  a  sub- 
stance is  heated,  and  the  contraction  when  cold  is  applied.  The 
following  chart^  has  been  prepared  recently  to  show  how  some  of  the 
more  common  materials  behave  in  this  respect: 

TABLE   I. — ^AVERAGE   EXPANSION  COEFFICIENTS.      RANGE    20°  TO  50°  C. 

Expansion. 
Material.  Coeff.  x  lO^ 

Tooth  (root) 8.3 

Tooth  (across  crown) 11.4 

Tooth  (root  and  crown) 6.4 

"                  8.7 

"                   "                  8.3 

Synthetic  porcelain 7.1 

"                " 8.1 

"                " 7.5 

Amalgam    H ■      .      .  26.4 

C 25.0 

K 22.1 

P 24.5 

A 25.4 

B 28.0 

L 24.8 

C    .......  25.0 

C 24.7 

C 28.0 

Porcelain  (Bayeux) 4.1 

Gold 14.4 

Platinum .      .' .  9.0 

Silver 19.2 

Mercury  (linear) 60.6 

Zinc 29.2 

Tin 22.3 

Copper 16.8 

Gutta-percha 198.3 

Aluminum 23.1 

Steel 11.0 

Note. — The  above  expansions  are  tabulated  as  amount  of  expansion,  in  microns,  for 
a  specimen  1  mm.  in  length,  when  heated  1°  C.,  e.  g.,  amalgam  C  wUl  change  25  microns 
per  meter  per  degree;  or,  in  terms  of  a  specimen  1  cm.  long  (the  approximate  diameter 
of  a  molar)  the  expansion  is  0.25  micron  per  degree  =  2.5  micron  per  10  degree  range  = 
12.5  microns  per  50  degree  range,  etc. 

1  Souder  and  Peters, 


366 


PROPERTIES  OF  FILLING  MATERIALS 


Strength  of  Amalgams. — Strength  of  alloys  indicates  those  proper- 
ties by  which  alloys  sustain  the  application  of  force  or  strain  without 
yielding  or  breaking,  and  may  be  considered  under  two  heads,  namely, 
crushing  resistance  and  flow.  Crushing  resistance  is  that  property 
by  vu-tue  of  which  alloys  resist  force  without  fracturing,  while  flow 
is  that  property  by  virtue  of  which  they  resist  force  without  change 
in  shape. 


2  4000 

O 

< 

J 

D 

o 

§  3000 

u 
a. 


^  2000 

z 


1000 


• 

X 

•  1 
• 

•  • 

' 

/ 

A 

/ 

''. 

X 

/ 

/ 

/ 

0  0.5 

MERCURY-ALLOY   RATIO 


1.5  20 

PACKED  UNDER  141  KILOS 


Fig.  344. 


— Effects  of  varying  relative  amounts  of  mercury  and  alloy  that  are  mixed 
together  in  making  an  amalgam. 


Crushing  resistance  of  dental  amalgams  may  be  treated  (1)  as  a 
property  of  the  alloys  used  to  form  amalgams,  and  (2)  as  a  property 
of  the  amalgam  mass.  The  crushing  resistance  of  the  alloys  from  which 
dental  amalgams  are  made  seems  to  be  controlled  primarily  by  the 
composition  of  the  alloy,  and  secondarily  by  the  annealing  and  possibly 
by  the  process  of  alloying  and  chilling.  It  should  be  obvious  that  as 
the  percentages  of  silver  and  copper  are  increased,  strength  will  be 
increased,  other  things  being  the  same.  Tin  being  a  very  soft  metal, 
will  decrease  the  strength  as  the  percentage  is  increased,  other  things 
being  equal.  Tlie  effect  of  zinc  on  strength  seems  to  lie  between  tin 
and  silver  and  copper.  The  crushing  resistance  of  amalgam  prepared 
from  tjiese  allovs  presents  not  oxA^  the  same  phenomena  as  tjie  alloys^ 


1 

1 

4000 

'.< 

»^^^ 

< 

•   • 

•  • 

• 
• 

t 

3000 

/ 

/ 

f 

2000 

I 

f 

1000 

0 

' 

0  0.5  1.0 

WERCURY-ALLOY  RATIO 


1.5  2.0 

PACKED  UNDER  400  KILOS 


Fig.  34.5.— Modification  of  Fig.  344,  produced  by  increasing  packing  pressure  from 
141  to  400  kg.  per  cir.  cm. 


H 
Z 
kJ 
O  4000 

a. 


o 

e 
u 

^  3000 


3 

Z  2000 


(9 

Z 

u 

i    1000 

z 

X 

«J 

O  0 


• II 


0  OS  1.0 

MLRCURY-ALLOY  RATIO 


1.5  2.0 

PACKED  UNDE.R  1131  KILOS 


Fig. 


346. — Modification  of  Figs.    344  and  345  by  further  increase  of  packing  pressure 
to  1131  kg.  per  cir.  cm. 


368 


PROPERTIES  OF  FILLING  MATERIALS 


but  the  additional  complications  arising  from  the  union  of  the  mercury 
with  the  alloy,  and  the  conditions  under  which  these  alloys  are  com- 
bined with  mercury  in  the  practice  of  dentistry. 

Gray  has  shown  (Figs.  344/  345^  and  346^)  that  as  the  pressure  in 
packing  is  increased  from  141  kg.  to  1131  kg.,  the  crushing  resistance 
in  circular  centimeters  is  raised  from  800  kg.  to  4600  kg.  There  seems 
to  be  no  doubt  that  the  variations  in  the  pressure  used  in  packing 
amalgam  in  the  great  variety  of  places  where  this  material  is  used  in 
the  practice  of  deatistry  result  in  similar  variations  in  strength. 


a: 

UJ 

S  4000 
O 


o   3000 


^  2000 


1000 


X 

\ 

< 

K 

\ 

« 

k: 

N 

t  , 

•I 

K 

-a^H*-, 

»*a-«. 

20°  4-0°  60° 

TEMPERATURE  CENTIGRADE 


80° 


Fig.   347. — Effect  of  temperature  on  crushing  strength.    Transition  region  shown  by  the 
rapid  fall  in  strength  between  70°  and  80°. 


The  same  writer  has  shown  that  the  temperature  of  the  amalgam 
when  it  is  subjected  to  stress  has  a  marked  influence  upon  its  resistance 
to  force  (Fig.  347^). 

When  this  feature  of  the  behavior  of  amalgam  was  first  published 
it  was  questioned  somewhat  on  account  of  the  comparatively  low 
temperatures  used  for  the  tests,  but  as  the  work  was  checked  up  by 
experiments  it  seemed  to  be  no  more  cause  for  surprise  than  was  the 
discovery  of  the  low  temperatures  at  which  alloys  for  amalgams  would 


1  Gray,  Arthur  W. 


2  Ibid. 


3  Ibid. 


Ibid. 


NATURE  OF  AMALGAM       '  369 

become  annealed.  As  this  is  compared  with  the  various  processes  in 
nature  which  are  known  to  be  going  on  at  equally  low  temperatures, 
and  with  the  known  behavior  of  other  materials  at  different  tempera- 
tures, it  seems  strange  that  other  investigators  had  not  observed  this 
phenomenon  before.  Hadfield,  Dewar  and  Le  Chatelier^  and  others 
have  investigated  the  tensile  strength  and  elongation  of  copper  at 
temperatures  varying  from  —182°  C.  to  530°  C.  and  found  that  the 
tensile  strength  was  approximately  six  times  as  much  at  the  former 
temperature  as  it  was  at  the  latter.  They  found  the  elongation  was 
approximately  three  times  as  much.  The  tensile  strength  of  aluminum 
has  likewise  been  studied^  and  found  to  be  much  less  at  elevated  tem- 
peratures. Several  alloys  of  commercial  interest  have  been  studied 
with  similar  results.  There  seems  to  be  so  much  similarity  between  the 
apparent  behavior  of  amalgam  at  different  temperatures  and  what  is 
known  about  the  behavior  of  other  metals  that  the  phenomena  shown 
in  Fig.  347  will  probably  be  accepted.  It  is  possible,  however,  that  the 
curve  shown  by  Gray  will  be  modified  somewhat  for  the  reason  that 
the  400  kg.  per  circular  centimeter  pressure  used  in  making  the  fillings 
for  the  tests  seems  somewhat  higher  than  is  permissible  in  practice. 
When  metals  have  been  worked  in  the  cold  state  or  have  been  sub- 
jected to  high  pressures  their  decrease  in  strength  is  more  rapid  as  the 
temperature  rises  than  in  those  which  have  been  cast  and  allowed  to 
cool.  From  this  it  seems  likely  that  the  curve  shown  may  be  modi- 
fied to  show  a  little  less  rapid  change  in  crushing  strength  with  rise 
in  temperature. 

From  the  beginning  of  the  use  of  amalgam  it  has  been  recognized 
that  the  time  devoted  to  trituration  of  the  mercury  and  alloy  had  a 
marked  effect  upon  the  strength  of  amalgam.  With  comparatively 
simple  instruments  for  the  purpose  of  detecting  differences  in  strength, 
teachers  and  practitioners  alike  have  been  able  to  show  that  fillings 
could  be  made  to  show  little  or  no  strength  when  there  had  been  little 
trituration  of  the  mercury  and  alloy,  and  that  as  the  trituration  time 
was  increased,  the  strength  increased  rapidly  to  the  maximum.  With 
this  knowledge  of  the  situation,  the  author  carried  on  an  appreciable 
number  of  experiments  to  determine  approximately,  at  least,  how  much 
trituration  was  necessary  in  order  to  develop  the  maximum  strength 
of  amalgam  and  stated  in  the  former  edition  of  this  book  that  it 
required  from  three  to  five  minutes,  depending  upon  the  rapidity  of 
the  operation.  It  should  be  obvious  that  one  operator  may  leisurely 
triturate  the  mercury  and  alloy  while  another  may  work  rapidly  and 
as  a  result  accomplish  double  the  number  of  units  of  work.    Recently 

1  Law,  E.  F. :  Alloys  and  Their  Industrial  Application.  *  Ibid, 

24 


370 


PROPERTIES  OF  FILLING  MATERIALS 


the  matter  of  trituration  time  has  been  given  further  consideration 
and  found  to  be  approximately  as  previously  stated.  It  may  be  noted 
that  Fig.  348^  shows  that  the  trituration  may  be  carried  on  for  six 
minutes  before  the  incipient  setting  begins  to  show  a  decline  in  the 
crushing  strength.  Since  the  amount  of  annealing  that  was  given 
the  alloy  used  for  the  tests  and  the  rapidity  of  the  operator  are  unknown, 
it  appears  to  the  author  there  is  a  possibility  that  the  person  who 
triturated  the  mercury  and  alloy  for  these  tests  worked  a  little  slower 
than  the  oue  who  made  those  for  the  author  and  as  a  result  did  not 


4000 


3000 


2000 


1000 


O  -^2  4 

TRITURATION  TIME  IN  MINUTES 


1131 
400 
141 


Fig.  348. — Gain  in  crushing  strength  produced  by  increasing  trituration  time. 


reach  a  stage  in  the  setting  of  the  mass  where  the  decline  begins  quite 
so  soon. 

It  seems  quite  probable,  therefore,  that  six  minutes  is  the  maximum 
time  that  will  bring  out  the  maximum  strength.  It  should  be  kept  in 
mind  in  this  connection  that  if  the  maximum  time  has  been  devoted  to 
trituration,  the  packing  must  be  done  very  quickly.  Inasmuch  as 
this  is  not  always  possible  in  the  practice  of  dentistry,  it  is  questionable 
whether  it  is  advisable  to  triturate  the  mercury  and  alloy  which  have 
been  fully  annealed  for  a  longer  time  than  four  and  one-half  or  five 
minutes. 

1  Gray,  Arthur  W. 


NATURE  OF  AMALGAM  371 

In  arriving  at  accurate  conclusions  with  respect  to  the  strength  of 
amalgams  it  is  assumed  that  the  proper  proportions  of  mercury  and 
alloy  have  been  used.  If  in  one  instance  too  little  mercury  has  been 
used  there  will  have  been  too  little  alloy  dissolved  in  the  mercury,  and 
the  mass  when  set  will  be  comparatively  weak.  If,  on  the  other  hand, 
too  much  has  been  used  and  it  has  been  left  in  the  mass,  the  filling  will 
be  comparatively  weak,  due  to  the  presence  of  more  mercury  than  is 
necessary  to  react  with  the  alloj^  used.  By  referring  to  Fig.  344,  it 
may  be  seen  that  the  maximum  strength  is  obtained  when  about  1.6 
per  cent,  of  mercury  is  used.  It  may  also  be  seen  that  no  further 
increase  of  strength  was  observed  by  further  increasing  the  percentage 
of  mercurj'  and  that  the  pressure  was  sufficient  to  remove  the  excess  of 
mercury,  for  no  decline  in  strength  is  sho\\Ti  as  the  proportions  of 
mercury  reach  2.5  per  cent.  If  in  this  case  the  pressure  had  been  low 
there  would  have  been  a  decline  of  strength  sho^Mi,  as  excess  mercury 
was  retained  in  the  filling. 

It  seems  to  be  generally  accepted  that  the  age  of  a  filling  should  be 
given  when  statements  regarding  strength  are  made,  for  it  is  well 
known  that  strength  begins  to  develop  as  the  setting  progresses.  In- 
asmuch as  the  reaction  curves  previously  given  seem  to  indicate  con- 
tinuations of  the  setting  process  that  begins  as  soon  as  the  alloy  and 
merciu-y  begm  to  combine,  it  is  to  be  expected  that  variations  in  the 
strength  will  follow  variations  in  the  reaction  curve.  It  may  be  noted 
that  Gray  has  sho^Ti  the  strength  of  these  amalgams  at  the  end  of 
forty  days.  This  is  undoubtedly  quite  accurate  for  the  pressures  he 
has  used.  For  lower  pressures,  such  as  are  common  in  inaccessible 
places  in  the  practice  of  dentistry,  it  may  be  expected  that  the  maxi- 
mum strength  will  not  develop  until  at  least  three  or  four  months 
have  elapsed. 

It  is  well  kno;^T^i  that  the  heat  treatment  given  to  the  cut  alloy  has 
a  marked  effect  upon  the  strength.  When  freshly  cut  particles  of 
alloy  are  combined  with  mercury  the  combination  takes  place  so 
rapidly  that  it  is  not  possible  to  continue  the  trituration  to  a  place 
where  the  mass  becomes  fine  grained  for  the  reason  that  incipient 
setting  takes  place.  This  mass  appears  to  be  composed  of  a  cementing 
layer  of  amalgam  around  the  comparatively  coarse  alloy  particles. 
If  the  alloy  be  annealed  the  combination  takes  place  less  rapidly  and 
trituration  may  be  carried  on  further,  resulting  in  a  mass  in  which 
there  are  particles  much  smaller.  The  general  effect  of  making  the 
combination  of  mercury  and  alloy  slower  seems  to  be  to  increase  the 
strength  up  to  a  certain  point  and  then  a  continuation  of  the  annealing 
seems  to  cause  a  decline  in  the  strength.  The  amount  of  annealing 
that  should  be  given  to  each  formula  varies  with  the  composition  of  the 
alloy  and  the  mechanical  treatment  given  it  during  the  cuttmg  process. 


372  PROPERTIES  OF  FILLING  MATERIALS 

Flow  of  Amalgam. — ^A  solid  metal  can  flow  like  a  viscous  fluid  if 
sufficient  pressure  is  applied.^  The  property  seems  to  be  different  with 
different  metals  and  varies  with  different  forms  of  the  savie  metal. 
Some  metals  with  a  distinctly  granular  structure  seem  to  flow  less 
than  the  same  metal  when  in  a  less  granular  structure,  though  the 
tenacity  and  elongation  of  the  two  forms  may  be  nearly  identical.  The 
differences  in  the  rate  of  flow  between  different  metals  depend  largely 
upon  their  plasticity,  by  virtue  of  which  they  yield  to  the  pressure  and 
allow  the  molecules  to  slip  over  each  other  and  assume  new  positions. 

If  we  subject  a  bar  of  pure  silver  or  copper  3  mm.  square  to  a  force 
of  200  kg.  it  will  yield  a  very  little  soon  after  the  pressure  is  applied, 
then  it  will  yield  no  more  until  the  weight  is  increased.  If  we  try  a 
similar  block  of  tin  in  the  same  way  we  find  that  it  yields  much  more 
easily;  15  kg.  will  cause  considerable  change,  and  if  we  leave  it  under 
this  pressure  without  increasing  it  will  continue  to  yield  until  the 
greater  part  of  the  tin  has  flowed  from  between  the  points  and  been 
reduced  to  a  thin  sheet.  One  writer^  has  stated  that  this  is  proof  that 
tin  is  not  only  a  softer  metal  but  has  a  physical  property  totally  dif- 
ferent from  any  possessed  by  silver,  the  property  of  continuous  flow 
under  a  given  pressure.  This  indicates  the  effect  of  tin  and  silver  upon 
flow,  though  it  implies  that  the  flow  of  tin  is  a  peculiar  property  rather 
than  that  it  is  a  property  of  all  metals,  tin  being  one  possessed  of  a 
high  rate  of  flow. 

A  hard  metal  like  silver  has  an  elastic  limit  wjiich  must  be  exceeded 
and  the  pressure  maintained  in  excess  if  a  continuous  flow  is  produced, 
while  a  soft  metal  like  tin  has  practically  no  elasticity,  and  is  therefore 
capable  of  being  changed  in  form  with  almost  any  pressure.  The 
composition  of  the  alloy  controls  largely  the  property  of  flow,  the  hard 
and  elastic  metals  reducing  it  and  the  soft  ones  increasing  it.  The 
effect  of  annealing  upon  flow  depends  upon  the  composition,  some 
formulae  being  affected  more  by  annealing  than  others.  Generally 
speaking  the  softening  of  an  alloy  by  annealing  increases  flow,  although 
with  some  formulse  flow  may  be  slightly  decreased  by  annealing. 

The  manner  of  incorporating  the  alloy  and  mercury,  percentage 
of  mercury  used  during  amalgamation,  the  condition  of  the  cut,  or  the 
amount  of  mercury  left  in  the  filling  modify  flow,  although  apparently 
not  with  regularity  even  in  a  given  alloy.  The  least  change  in  compo- 
sition so  modifies  flow  that  each  of  these  phases  must  be  considered 
separately  with  each  formula.  An  excess  of  mercury  left  in  the  filling, 
however,  increases  flow  quite  regularly,  there  being  some  exceptions 
in  the  ternary  amalgams,  which  are  high  in  silver  and  low  in  tin.    The 

1  Hiorns:  Mixed  Metals  and  Metallic  Alloys. 
*  Black:  Operative  Dentistry,  vol.  ii. 


NATURE  OF  AMALGAM 


373 


property  of  flow  depends  largely-  upon  the  softness  and  absence  of 
elasticity,  and  is  at  its  maximum  in  alloys  known  as  low  silver  alloys, 
Spheroiding  of  amalgams  is  a  phenomenon  associated  with  flow  and 
increase  in  volume.  It  has  been  held  that  amalgams  possess  a  strong 
tendency  to  become  spherical  in  shape,  due  to  the  influence  of  mercury 
which  is  spherical  in  shape  when  divided  finely.  This  influence  which 
mercury  is  supposed  to  exert  seems  to  be  a  misconception  of  the  cause 
of  the  tendency  to  spheroid.  Mercury  is  spheroidal  or  globular  in 
shape  when  divided  somewhat,  the  smaller  the  particle  the  more 
nearly  a  sphere.  There  seems  to  have  been  a  tendency  to  regard  this 
as  a  property  peculiar  to  mercury.  This  is  not  true.  The  property 
is  possessed  by  other  metals  when  in  a  fluid  condition. 


Fig.  349. 


The  above  illustrations  show  a  spheroided  filling  produced  by  an 
alloy  which  increased  in  volume  and  flowed  easily.  It  was  composed 
of  silver,  49  per  cent.;  tin,  49.1  per  cent.;  zinc,  1.9  per  cent.  Fig.  350 
shows  the  surface  of  a  filling  made  from  this  plastic  alloy  and  kept  in 


Fig.  351. 


the  thermostat  at  body  temperature  for  eight  months.  The  surface  is 
seen  to  be  spheroided.  Fig.  349  shows  a  companion  filling  like  that  of 
Fig.  350,  except  that  the  walls  of  the  test-tubes  are  highly  polished, 
this  being  accomplished  by  making  the  test-tube  with  removable 
bottom,  as  seen  in  Fig.  351.    It  may  be  seen  that  the  filling  (Fig.  349), 


374  PROPERTIES  OF  FILLING  MATERIALS 

instead  of  spheroiding,  has  risen  nearly  as  much  at  the  borders  as  it 
has  at  the  center  of  the  filHng.  The  filKng  (Fig.  350)  has  assumed  a 
much  more  spheroidal  surface  than  the  one  (Fig.  349),  due  apparently 
to  the  walls  of  the  cavity  being  purposely  roughened.  This  spheroidal 
tendency  seems  to  disappear  somewhat  with  alloys  high  in  silver  and 
copper,  these  alloys  possessing  less  flow.  It  has  not  been  produced 
to  any  extent  in  alloys  which  do  not  expand  decidedly  and  flow  com- 
paratively easily,  although  irregular  expansions  and  contractions  appear 
to  produce  in  some  instances  bulged  surfaces  and  in  others  concave 
surfaces  in  alloys  possessing  little  flow  and  expansion. 

General  Considerations. — Washing  Amalgam. — ^Much  importance 
has  been  attached  to  the  washing  of  the  alloy  particles  during  the 
process  of  incorporation  with  the  mercury.  Such  substances  as  dilute 
acids,  alcohol,  ether,  chloroform  and  sodium  carbonate  have  been  used, 
but  with  doubtful  value  in  many  cases,  for  the  reason  that  the  pro- 
fession has  not  mastered  the  technic  of  mixing  the  alloy  and  mercury. 
The  advantage  of  washing  the  alloy  is  to  remove  some  of  the  metallic 
compounds  that  have  formed  during  the  cutting  process  and  annealing, 
process,  and  by  subsequent  standing  exposed  to  contaminating  atmos- 
pheres for  some  time.  It  has  been  stated  that  washing  alloys  increases 
shrinkage,  but  this  can  be  accounted  for  easily  when  it  is  considered 
that  practically  all  alloys  had  considerable  shrinkage  previous  to  1895. 
Since  that  time  alloys  have  been  made  that  possessed  little  shrinkage 
and  litte  or  nothing  has  been  said  about  the  effect  of  washing  alloys. 
Another  disadvantage  of  washing  alloys  is  that  it  is  difficult  to  prevent 
some  of  the  material  from  becoming  incorporated  in  the  amalgam  as  a 
foreign  body,  thus  lessening  the  strength.  If,  however,  the  material 
used  for  washing  actually  loosens  the  metallic  coinpounds  upon  the 
surface  of  the  alloy  particles,  or  if  it  dissolves  them  and  they  are  then 
well  removed  by  rolling  the  amalgam  mass  into  a  thin  sheet  between 
two  pieces  of  absorbent  material,  the  result  will  be  a  better  solution  of 
the  alloy  in  the  mercury  with  a  brighter  color  and  better  strength. 

A  still  better  plan  than  washing  the  alloy  at  the  time  of  making  a 
mix  with  mercury  is  to  wash  it  some  time  in  advance.  This  is  probably 
better  done  by  the  manufacturer,  though  it  may  be  desirable  for  the 
dentist  to  do  it  if  a  quantity  of  alloy  has  become  contaminated  by 
exposure  after  leaving  the  manufacturer. 

One  of  the  leading  manufacturers  has  recently  taken  out  a  patent^  on 
a  process  for  washing  and  drying  the  alloy  after  it  is  cut  and  annealed. 
It  seems  likely  that  hydrochloric  acid  in  small  quantities  in  alcohol 
is  used  in  this  instance. 

1  Alloy  and  Method  of  Purifying  Same,  Paul  Poetschke,  patent  No.  1278744. 


NATURE  OF  AMALGAM  375 

Thermal  and  Chemical  Relations. — Amalgam,  like  gold  and  other 
metals,  is  a  conductor  of  thermal  impressions.  Just  where  amalgam 
stands  as  a  conductor  of  heat  and  electricity  is  not  known,  although 
it  can  safely  be  placed  quite  near  gold.  The  composition  of  the 
amalgam  will  influence  its  conductivity.  Any  rise  in  temperature 
will  usually  retard  and  a  fall  in  temperature  will  increase  conductivity, 
although  the  resistance  of  alloys  to  conductivity  does  not  always 
behave  in  a  manner  that  would  be  expected  from  the  nature  of  their 
constituents.  Certain  anomalies  which  are  known  to  exist  make  it 
seem  possible  that  certain  temperatures  with  certain  formulae  might 
result  in  a  variation  from  the  general  rule.  Dental  amalgams  are 
practically  insoluble  in  the  fluids  of  the  mouth.  The  common  solvent 
found  in  the  oral  cavity,  lactic  acid,  affects  them  only  a  little.  There 
is,  however,  a  constant  wasting  away  of  many  amalgams,  due  to  the 
formation  of  compounds  which  are  soluble  in  the  oral  fluids  or  which 
are  worn  off  during  mastication.  Amalgams  that  are  high  in  copper 
furnish  an  example  of  the  constant  wasting  which  may  be  due  to  the 
formation  of  the  green  basic  carbonate  in  small  quantities  or  salts 
from  the  action  of  hydrogen  sulphid  and  soluble  sulphids.  The  two 
principal  classes  of  alloys  now  in  use  are  not  affected  in  this  manner  to 
any  appreciable  extent. 

There  are  probably  no  alloys  in  use  which  exert  any  particular 
influence  upon  the  tooth  tissues  except  those  high  in  copper  or  possibly 
silver  or  tin.  One  or  two  alloys  containing  high  percentages  of  copper 
are  heralded  as  great  tooth  preservers,  not  simply  because  they  are 
free  from  contraction,  expansion  and  flow  after  insertion,  but 
because  they  possess  "antiseptic  properties."  A  critical  examination 
of  them  fails  to  reveal  any  reason  why  they  should  exert  a  marked 
influence  on  account  of  their  comparative  insolubility.  The  action 
of  copper  amalgam  upon  the  tooth  tissues,  however,  has  been  studied 
by  Miller,  Fletcher,  Witzel  and  others,  and  the  general  opinion  seems 
to  be  that  it  possesses  antiseptic  properties  not  possessed  by  amalgams 
containing  small  percentages  of  copper.  (See  Copper:  1.  Amalgam. 
2.  Cements.) 

Copper  Amalgam. — Copper  Amalgam  differs  so  markedly  from  all 
other  amalgams,  both  ui  composition  and  behavior,  that  it  deserves 
separate  consideration.  The  foregoing  data  apply  only  m  slight 
degree  to  copper  amalgam.  It  is  an  alloy  of  copper  and  mercury  and 
may  be  made  by  adding  freshly  precipitated  and  washed  metallic 
copper  to  an  excess  of  mercury  until  the  solution  is  complete;  the 
excess  mercury  is  then  removed  by  compressing  the  mass  in  chamois 
skin.  The  portion  which  does  not  pass  through  the  chamois  skin 
is  packed  into  molds  and  allowed  to  stiffen.    The  product  may  be 


376  PROPERTIES  OF  FILLING  MATERIALS 

purchased  in  the  form  of  small  tablets,  which  may  be  softened  by  heat- 
ing slowly  in  a  spoon  (Fig.  352)  after  which  it  may  be  molded  and 
packed  into  the  cavity.  Many  dentists  have  made  copper  amalgam 
by  grinding  copper  filings  in  a  mortar  with  dilute  acids  and  washing 
with  a  variety  of  substances  immediately  before  insertion  of  the 
amalgam.  A  far  better  method,  and  one  which  yields  a  product  of 
greater  purity  and  uniformity,  has  been  suggested  by  Dr.  E.  C.  Kirk. 
It  is  done  by  precipitating  the  copper  directly  into  the  mercury  by 
electrolysis.  "This  may  be  done  conveniently,"  says  Dr.  Kirk,  "by 
pouring  a  quantity  of  mercury  into  a  suitable  glass  vessel — a  small 
battery  jar,  for  example — and  suspending  a  thick  plate  of  copper,  by 
means  of  a  wooden  support,  some  distance  above  the  surface  of  the 
mercury. 


Fig.  352. 

"A  saturated  solution  of  cupric  sulphate  is  then  poured  into  the  jar 
until  the  copper  plate  is  completely  submerged.  The  cathode  pole 
of  a  battery  or  other  source  of  electric  current  is  then  connected  with 
the  layer  of  mercury  and  the  anode  with  the  copper  plate.  All  of  the 
cathode  electrode  that  is  in  contact  with  the  cupric  sulphate  solution 
should  be  insulated  with  gutta-percha  and  only  the  point  which  is  in 
contact  with  the  mercury  left  exposed.  The  passage  of  the  current 
causes  solution  of  the  copper  from  the  anode  and  deposits  it  in  the 
mercury  continuously  as  long  as  the  foregoing  conditions  are  main- 
tained. The  precipitation  should  be  continued  until  the  mercury  is 
saturated,  which  will  be  evidenced  by  the  appearance  of  the  character- 
istic red  color  of  the  excess  of  copper  at  the  cathode  pole. 

"  When  the  saturation  point  has  been  fully  reached  the  mass  should 
be  washed,  first  in  dilute  hydrochloric  acid  and  then  in  water,  dried 
and  compressed,  as  is  usual  with  this  amalgam  when  prepared  by  the 
ordinary  process."  Copper  amalgam  prepared  in  this  manner  changes 
in  volume  very  little,  if  at  all,  as  a  result  of  the  union  of  mercury  with 
the  copper,  either  in  the  mixing  or  subsequent  to  its  insertion  into  the 
oral  cavity.  The  only  known  alteration  in  form  that  occurs  is  the 
comparatively  small  one  resulting  from  the  thermal  changes.  It  is 
antiseptic.  These  two  qualities  make  one  of  the  best  tooth  preservers 
now  in  use,  although  it  has  other  qualities  so  undesirable  as  to  exclude 


NATURE  OF  AMALGAM  377 

its  use  in  a  great  majority  of  cases.  It  turns  almost  black  in  most 
mouths,  has  a  peculiar  metallic  taste,  is  sometimes  a  marked  cause  of 
voltaic  disturbance,  and  if  moisture  through  any  cause  enters  between 
it  and  the  walls  of  the  tooth  the  latter  becomes  discolored.  Often, 
although  no  visible  leakage  of  the  filling  is  apparent,  there  is  discolored 
tooth  tissue,  due  probably  to  the  absorption  of  the  salts  of  copper  into 
the  dentinal  tubuli.  Copper  amalgam  is  not  quite  as  indestructible  in 
the  fluids  of  the  mouth  as  other  amalgams,  as  it  readily  forms  salts 
which  are  either  dissolved  or  carried  away  by  abrasion.  This  is  com- 
monly shown  by  a  sort  of  cupping  out  of  the  surface  of  the  filling. 

Classification  of  Amalgams. — Amalgams  may  be  divided  into 
classes  according  to  the  number  of  constituent  metals.  A  binary 
dental  amalgam  may  be  represented  by  copper  and  mercury  or  palla- 
dium and  mercury,  each  of  which  has  a  very  limited  usefulness  in 
dentistry.  Some  of  the  older  alloys  of  silver,  tin  and  mercury,  such  as 
that  designed  by  Dr.  Townsend,  represent  what  may  be  called  a  ternary 
dental  amalgam.  Amalgams  of  silver,  tin,  copper  and  mercury,  such 
as  designed  by  Dr.  Flagg,  may  be  said  to  be  quaternary  dental  amal- 
gams. This  class  is  also  represented  by  the  so-called  plastic  amalgams 
made  since  1895-1896,  and  composed  of  silver,  tin,  zinc  and  mercury. 
The  high  percentage  silver  amalgams,  composed  of  silver,  tin,  copper, 
zinc  and  mercury,  may  well  represent  a  quinary  amalgam.  The  terms 
binary,  ternary,  etc.,  have  not  gained  in  popularity  with  the  profession 
in  the  last  decade,  although  amalgams  are  in  use  representing  each  of 
the  classes  mentioned. 

Buying  and  Keeping  Alloys. — The  question,  "Which  is  the  best 
alloy  to  buy?"  is  asked  so  often  that  it  seems  quite  certain  that  the 
profession  in  this  particular  does  not  exercise  the  same  judgment  with 
which  it  selects  other  dental  materials.  It  indicates  quite  clearly  that 
there  is  yet  much  mystery  surrounding  the  purchase  of  an  alloy.  When 
supplies  the  nature  of  which  is  not  understood  are  required  the  majority 
of  the  profession  select  them  from  a  dealer  who  is  believed  to  be  reliable 
in  this  respect  and  who  is  known  to  be  wholly  reliable  in  others.  As  a 
rule  the  larger  supply  houses  are  best  equipped  for  distributing  uniform 
supplies  of  all  kinds,  and  most  likely  to  secure  the  services  of  competent 
men  to  manufacture  their  products.  This  is  true  in  the  manufacture  of 
alloys  and  should  be  used  as  a  guide  in  their  selection.  Sometimes  a 
good  product  comes  from  a  dealer  who  is  not  well  nor  favorably  known, 
but  this  is  the  exception  rather  than  the  rule.  Alloys  and  cements  above 
all  other  products  should  be  made  and  placed  upon  the  market  by  com- 
petent chemists  if  the  dentist  is  to  be  rewarded  for  his  work.  The 
practicing  dentist  should  never  attempt  the  manufacture  of  these 
products  himself  without  first  spending  considerable  time  preparing 


378  PROPERTIES  OF  FILLING  MATERIALS 

himself  by  learning  the  peculiarities  of  these  products  with  special 
apparatus  built  for  the  purpose. 

Dentists,  as  a  rule,  are  kept  changing  alloys  by  solicitous  dealers 
who  advance  this  or  that  quality  of  their  alloy  as  a  cure-all.  For 
example,  one  dealer  lauds  his  product  as  being  superior  because  it 
contains  more  silver  than  a  like  article  made  by  another.  Another 
makes  the  same  claims  regarding  the  quantity  of  zinc  in  his  product. 
Others  advance  the  argument  that  the  manner  of  cut  of  their  manu- 
facture has  much  to  do  with  the  success  attending  its  use,  and  so  it  is 
with  nearly  every  dealer.  These  arguments  generally  reward  the 
dealer  with  sales  because  dentists,  as  a  rule,  are  not  sufficiently 
informed  on  the  subject  to  enable  them  to  judge  the  merits  of  the 
products  themselves. 

It  is  true  that  some  of  the  best  manufacturers  differ  as  to  what  con- 
stitutes the  "best  alloy,  all  things  considered,"  but,  as  a  rule,  the  differ- 
ence of  opinion  is  an  honest  one  rather  than  an  effort  on  the  part  of  the 
producer  to  lessen  the  first  cost  of  the  article.  This  is  shown  by 
several  leading  dealers'  products,  which  are  found  to  contain  from  65 
per  cent,  of  silver  to  68  per  cent,  of  silver,  yet  each  will  claim  to  have 
an  alloy  made  after  Dr.  Black's  plan,  etc.  The  maker  who  uses  68 
per  cent,  of  silver  knows  that  he  obtains  a  little  stronger  filling,  although 
he  is  conscious  of  the  fact  that  it  works  a  little  harder  and  sets  faster 
than  one  that  contains  only  65  per  cent,  of  silver.  On  the  other  hand, 
he  who  uses  65  per  cent,  of  silver  knows  that  his  product  works  a  little 
more  easily  aad  sets  a  little  more  slowly,  although  he  is  conscious  that 
it  is  a  little  weaker.  The  maker  who  uses  only  65  per  cent,  of  silver 
probably  considers  it  better  to  give  the  operator  a  little  more  time  to 
work  than  to  have  a  little  stronger  filling. 

The  same  is  true  of  the  quantity  of  zinc  now  used  in  high  percentage 
silver  alloys.  Some  claim  better  and  permanent  light  color  in  the  mouth 
as  a  result  of  the  use  of  a  little  more  zinc,  while  others  admit  a  loss  in 
color  as  a  result  of  its  elimination,  but  claim  to  have  a  product  more 
permanent  in  form,  as  a  rule.  Neither  disputes  the  other's  claims,  but 
each  places  greater  stress  upon  the  distinctive  qualities  of  his  product 
in  contrast  to  those  of  his  competitors.  Thus  it  becomes  a  matter  of 
judgment  which  quality  is  of  most  importance. 

The  leading  dealers'  high  percentage  silver  alloys  are  all  good,  well- 
made,  uniform  products,  and  except  for  the  difference  mentioned, 
they  are  nearly  of  equal  value  from  a  practical  standpoint.  Whether 
an  alloy  contains  65  or  68  per  cent,  of  silver  is  not  a  guide  to  the  quality 
of  either.  The  same  is  generally  true  with  the  small  quantities  of  zinc 
now  used,  although  it  is  quite  generally  understood  that  zinc,  while 
it  improves  color,  facilitates  change  in  volume  subsequent  to  insertion 


NATURE  OF  AMALGAM  379 

when  used  in  large  quantities.  This  is  not  so,  however,  if  used  in  small 
quantities.  Dentists  cannot  rely  upon  the  quantity  of  each  or  any 
constituent  as  a  guide  to  quality,  although  present  knowledge  of  the 
subject  confines  the  qualities  of  each  constituent  for  the  best  alloys 
to  the  ranges  stated.  All  things  considered  the  high  percentage  silver 
alloys  are  best,  and  should  be  chosen  by  dentists. 

There  are,  perhaps,  some  places  where  the  quick-setting  properties 
make  the  use  of  these  alloys  questionable,  but,  taken  as  a  general  rule, 
dentists  soon  learn  to  open  the  orifice  of  the  cavities  and  master  the 
manipulation  of  these  quick-setting,  stiff-working  products.  When 
purchasing  an  alloy  from  a  manufacturer  who  makes  his  product  in 
both  filings  and  shavings  the  filings  should  be  chosen.  Shavings  as  a 
rule,  are  too  coarse  and  not  of  the  proper  shape  to  permit  their  being 
dissolved  readily  in  mercury.  Not  all  manufacturers  make  their 
products  "cut  in  two  forms."  As  some  dentists  demand  them,  the 
maker  sometimes  can  hold  his  trade  by  no  other  means  than  by 
supplying  shavings  to  those  who  want  them. 

Some  makers  of  high  percentage  silver  alloys  make  only  one  grade 
of  alloys  as  regards  setting  qualities  while  others  make  their  product 
in  two  or  three  grades.  This,  too,  is  usually  done  to  catch  trade,  since 
most  makers  are  aware  that  if  more  than  one  grade  is  supplied,  some 
of  the  grades  are  imperfect  products  at  the  time  of  making.  "Rapid 
setting,''  "slower  setting,"  and  "slow  setting"  are  terms  used  to  desig- 
nate these  products.  They  are  the  same  in  composition,  but  have  not 
had  the  same  amount  of  annealing. 

Manipulation  of  Amalgam. — The  high  percentage  silver  alloys  are 
made  by  some  manufacturers  in  two  and  three  grades  of  setting.  They 
are  of  the  same  composition,  cut  just  the  same  and  marketed  just  the 
same,  except  that  some  packages  may  be  marked  "slow  setting," 
some  "rather  rapid  setting,"  and  others  "rapid  setting."  The  differ- 
ence in  their  production  is  in  the  amount  of  annealing  given  them, 
annealing  causing  them  to  set  more  slowly,  and  their  behavior  is 
usually  more  marked. 

Alloys  marked  "rapid  setting"  will  require  much  more  mercury  to 
amalgamate  them  if  they  have  not  been  in  stock  long  enough  to  be- 
come annealed.  They  will  set  so  rapidly  that  it  is  difficult  to  pack 
them  properly,  even  in  cavities  of  easy  access,  and  almost  impossible 
to  insert  them  where  there  is  not  ready  access.  The  amount  of  expan- 
sion that  will  take  place  subsequent  to  insertion  is  much  greater  with 
improperly  annealed  alloys.  The  finished  product  is  represented  by 
alloys  marked  "slow  setting."  Some  manufacturers  make  their  high 
percentage  silver  alloys  in  one  grade  only.  These  alloys  will  have  no 
mark  to  designate  their  manner  of  setting. 


380  PROPERTIES  OF  FILLING  MATERIALS 

The  alloy  to  be  selected  from  general  use  is  the  finished  product, 
although  the  occasional  use  of  "rapid  setting"  alloy  when  the  patient 
cannot  be  seen  by  the  operator  to  finish  the  filling  seems  to  be  desirable. 
It  should  be  remembered  that  while  alloys  marked  "rapid  setting" 
expand  more  than  those  marked  "slow  setting,"  contraction  and 
expansion  are  not  controlled  by  the  manipulation  of  them  during 
amalgamation  and  insertion.  The  operator  may  modify  these  move- 
ments but  he  cannot  control  them,  the  controlling  factors  being  com- 
position and  annealing. 

In  choosing  an  alloy  it  should  be  remembered  that  the  property 
which  can  be  controlled  most  by  the  operator  is  strength,  and  even 
then  the  alloy  must  be  properly  made  or  a  strong  filling  cannot  be 
produced. 

A  strong  filling  cannot  be  made  from  a  poor  alloy,  although  a  weak 
filling  may  be  made  from  a  good  one.  The  amount  of  alloy  necessary 
for  the  filling  should  be  placed  in  a  small  ground  glass  or  Wedgwood 
mortar  and  ground  with  the  required  amount  of  mercury  until  the 
mass  becomes  coherent  enough  to  be  turned  into  the  palm  of  the  hand 
conveniently,  after  which  it  should  be  kneaded  rapidly  and  vigorously 
for  from  three  to  five  minutes,  depending  upon  the  coarseness  of  the 
cut,  amount  of  annealing  and  composition  of  the  alloy. 

A  complete  union  of  the  alloy  and  mercury  cannot  be  effected  at 
ordinary  temperatures.  The  operator  must  be  guided  in  amalgamating 
these  alloys  by  the  consistency  of  the  mass.  It  should  be  fine  grained 
and  smooth  and  tough  enough  to  be  rolled  out  into  a  long  roll  without 
breaking  before  the  mixing  is  discontinued. 

The  amount  of  mercury  to  be  used  with  a  given  weight  of  alloy  is 
slightly  more  than  the  weight  of  the  alloy.  The  proportions  given  by 
most  makers  of  high  percentage  silver  alloys  are,  approximately: 
alloy,  5  parts;  mercury,  7  parts,  by  weight.  These  proportions  are 
as  nearly  correct  as  can  be  determined  by  experiment,  although  7 
parts  of  mercury  will  be  found  none  too  much  for  alloys  marked 
"rapid  setting."  The  low  percentage  silver  alloys  of  all  grades  will 
require  less  mercury.  It  will  usually  be  found  necessary  to  use  more 
than  equal  weight  of  mercury  for  a  given  weight  of  alloy  to  make  a 
smooth,  fine-grained  mass.  The  amount  of  mercury  to  be  used  with  a 
given  amount  of  alloy  of  known  composition  is  a  question  which  cannot 
be  answered  unless  the  "  condition  of  the  cut"  and  the  age  of  the  alloy 
are  known. 

All  alloys  require  less  mercury  as  they  become  annealed,  hence  the 
proportions  given  by  makers  of  alloys  are  correct  for  a  comparatively 
freshly  made  alloy  only. 

The  older  any  alloy  becomes,  the  more  easily  it  works,  the  weaker  it 


NATURE  OF  AMALGAM  381 

is,  and  the  less  mercury  it  requires,  although  if  properly  made,  it  will 
not  contract  appreciably.  It  may  be  noted  that  manufacturers  having 
similar  products  recommend  slightly  different  amounts  of  mercury  to 
be  used  with  a  given  amount  of  alloy.  Some  products  may  be  marked : 
"  Use  5  parts  of  alloy  with  7  parts  of  mercury;"  "4  parts  of  alloy  with 
5  parts  of  mercury;"  "9  parts  of  alloy  with  11  parts  of  mercury,"  etc. 
Chemical  analyses  show  many  of  these  alloys  to  be  nearly  identical 
in  composition,  but  there  is  some  diflference  in  the  "cut"  of  them,  a 
little  difference  in  the  amount  of  annealing,  and  probably  some  differ- 
ence in  the  manner  of  casting  and  cooling,  which  accounts  for  the 
variation  of  about  10  per  cent,  in  the  amount  of  mercury  required. 
The  correct  amount  of  mercury  to  be  used  during  amalgamation  does 
not  mean  the  amount  of  mercury  to  be  left  in  the  filling.  It  means 
that  a  slight  excess  of  mercury  should  always  be  used  to  start  the  filling, 
and  as  soon  as  it  is  noticed  it  should  be  removed.  Dr.  Black  has 
stated^  that  "it  is  certainly  best  to  have  just  the  right  amount,"  but 
in  the  same  sentence  states  that  "  superfluous  mercury  does  little  harm 
if  removed  as  soon  as  noticed." 

Dr.  Black  has  remained  practically  silent  on  the  subject  of  "per- 
manency of  form"  or  changes  in  amalgam  subsequent  to  insertion. 
Consistency  of  the  mass  seems  to  have  been  a  prominent  factor  with 
him.  This  is  unquestionably  a  vital  point  in  the  packing  process, 
but  an  amalgam  which  packs  nicely  may  be  the  most  unstable  kind. 

The  factor  of  supreme  importance  in  the  production  of  a  stable 
amalgam  is  a  fairly  complete  solution  of  the  alloy  in  the  mercury. 
This  can  only  be  produced  by  the  use  at  all  times  during  the  amal- 
gamation process  of  slightly  more  mercury  than  makes  a  mass  of  the 
consistency  to  pack  well.  As  soon  as  the  mass  begins  to  stiffen  and 
shows  a  tendency  to  set,  any  surplus  mercury  should  be  removed. 
There  is  not  even  a  remote  possibility  of  an  operator  producing  a  true 
amalgam  out  of  modern  high  percentage  silver  alloys  under  ordinary 
conditions.  The  best  that  can  be  done  is  to  produce  as  much  true 
amalgam  as  possible  around  the  undissolved  particles  of  alloy  and  yet 
keep  the  mass  of  a  consistency  to  pack  well.  The  latter  often  depends 
upon  the  presence  of  a  certain  number  of  undissolved  alloy  particles. 

Alloys  low  in  silver  and  those  high  in  silver  that  are  very  old  may 
dissolve  so  completely  in  mercury  that  the  mass  is  too  soft  to  pack 
well. 

The  ultimate  aim  of  the  operator  should  be  the  production  of  a 
mass  of  amalgam  that  is  both  stiff  and  tough  and  with  the  alloy  well 
into  solution  in  the  mercury.    To  accomplish  this  more  mercury  than 

1  Operative  Dentistry,  vol.  ii. 


382  PROPERTIES  OF  FILLING  MATERIALS 

is  to  be  left  in  the  filling  should  be  used  to  start  amalgamation.  This 
amount  is  stated  on  the  packages  of  alloy,  and  is  correct  for  freshly 
made  alloys.  The  alloy  and  mercury  may  be  weighed  on  a  balance  or 
turned  out  approximately  correct  by  an  experienced  operator  from  the 
containers.  It  is  immaterial  whether  the  exact  amount  of  mercury  is 
weighed  or  not,  as  the  operator  never  knows  whether  these  proportions 
are  correct.  It  is  convenient,  however,  to  have  them  weighed  in  the 
proportions  the  maker  has  determined  for  fresh  alloys,  since  a  little 
mercury  is  easily  removed  during  the  amalgamation  process  if  it  be 
found  necessary.  Earlier  observations  of  the  author  led  to  the  belief 
that  the  alloy  and  mercury  should  be  determined  and  weighed  care- 
fully, as  in  that  way  a  mass  was  obtained  of  a  consistency  to  pack 
well;  but  later  observations  on  the  changes  occurring  in  these  bodies 
subsequent  to  insertion  lead  to  the  belief  that  while  the  packing  of  an 
alloy  is  a  vital  point,  it  is  not  of  so  much  importance  to  the  life  of  the 
filling  as  to  have  the  alloy  worked  with  sufficient  (though  not  enough 
to  make  a  sloppy  mass)  mercury  at  all  stages  up  to  and  including  the 
packing. 

After  the  alloy  and  mercury  have  been  ground  in  a  mortar,  then 
turned  into  the  hand  and  worked  vigorously  for  a  few  seconds,  it  should 
be  noted  whether  the  mass  is  becoming  sloppy.  If  it  is,  a  little  mercury 
should  be  removed  quickly  between  the  thumb  and  forefinger.  The 
mass  should  not  be  put  into  pliers,  chamois  skin  or  muslin,  as  these 
processes  require  too  much  time.  Surplus  mercury  should  be  removed 
quickly,  or  the  mass  stifi^ens  so  that  the  object  of  the  operation  is 
partially  or  wholly  defeated.  The  mass  should  be  quickly  turned  into 
the  hand  and  again  kneaded  vigorously.  If  it  again  appears  a.  little 
sloppy,  remove  some  mercury  as  before.  Do  not  remove  too  much 
mercury  or  the  alloy  will  not  be  anywhere  near  completely  into  solu- 
tion. This  process  should  be  repeated  three  or  four  times,  the  last 
time  using  all  the  pressure  that  can  be  exerted  in  removing  the  excess 
mercury,  so  that  the  mass  will  be  stiff  enough  to  enable  it  to  be  packed 
well.  Three  or  four  repetitions  of  this  process  usually  consume  from 
three  to  five  minutes  and  result  in  a  tough,  stiff  and  fine-grained  mass. 

The  question  might  then  be  asked,  "What  is  an  excess  of  mercury?" 
And  it  might  be  answered  in  a  general  way  by  saying  that  it  is  the 
difference  between  the  amount  used  to  amalgamate  the  mass  and 
the  amount  that  should  be  left  in  the  filling. 

Any  amount  of  mercury  left  in  the  filling  over  and  above  an  amount 
which  makes  a  stiff,  tough  and  fine-grained  mass  of  amalgam  would,  of 
course,  be  regarded  as  superfluous.  Every  step  in  the  amalgamation 
process  should  be  done  rapidly,  not  allowing  the  amalgam  to  lie  still. 
If  the  mass  lies  still  a  few  seconds  it  stiffens  so  much  that  the  particles 


NATURE  OF  AMALGAM  383 

of  alloy  are  not  broken  down  in  the  mixing  and  surplus  mercury  is 
usually  retained  in  the  mass.  The  packing  should  be  begun  imme- 
diately using  flat-end  serrated  instruments.  Several  instruments  have 
been  designed  for  the  packing  operation,  but  the  consensus  of  opinion 
seems  to  favor  a  flat-end  or  cup-shaped  serrated  instrument  such  as 
shown  in  Chapter  IV. 

The  round  burnisher  has  been  used  with  some  degree  of  success,  but 
it  has  been  proved  that  it  does  not  give  the  maximum  density  or 
adaptation.  Pluggers  used  for  foil  fillings  have  been  used  somewhat 
successfully,  but  they  are  too  small  for  most  places,  and  as  a  result 
chop  the  amalgam  mass  to  pieces  and  do  not  compress  it.  Great  care 
should  be  exercised  in  packing  amalgam,  as  it  is  a  most  diflScult 
material  to  adapt  to  cavity  walls.  Too  little  pressure  results  in  a  weak 
filling.  Too  much  pressure,  such  as  that  exerted  by  sudden  blows 
from  a  mallet,  disturbs  the  whole  mass,  and  as  a  result  weakens  the 
filling.  Heavy,  steady  pressure  gives  the  strongest  and  best  adapted 
filling  (Figs.  344,  345  and  346).  The  amalgam  mass  should  not  be 
broken  up  any  more  than  is  necessary  for  convenience  in  placing  it 
into  the  different  parts  of  the  cavity.  Much  has  been  said  in  regard 
to  the  part  of  the  cavity  in  which  to  begin  the  packing,  but  it  is  doubt- 
ful if  any  one  method  can  be  carried  out  in  all  cavities. 

In  all  cases  an  effort  should  be  made  to  wedge  the  amalgam,  piece 
after  piece,  between  the  opposing  walls  or  between  one  wall  and  the 
already  condensed  amalgam,  finishing  by  wedging  some  amalgam 
between  the  main  mass  and  the  cavity  waHs.  Experience  will  teach 
how  much  force  can  be  used  in  the  wedging  and  what  size  of  pluggers 
will  not  chop  the  mass  to  pieces.  Instruments  of  varying  sizes  must  be 
in  readiness  on  the  table,  so  that  the  operator  has  at  his  immediate 
command  instruments  that  will  compress  and  wedge  amalgam  into 
any  pocket  or  crevice  that  may  appear  during  the  operation.  Amalgam 
to  be  packed  properly  must  be  stiff.  Soft  amalgam  cannot  be  packed 
to  make  even  a  fair  margin  when  examined  under  the  lens.  It  is  in 
this  part  of  the  work  that  the  modern  high  percentage  silver  alloys 
exceed  all  others,  the  low  percentage  silver  alloys  with  no  copper 
scarcely  deserving  comparison.  The  cavity  must  have  four  walls  if 
any  degree  of  compression  is  obtained.  With  the  great  variety  of 
matrices  and  matrix  retainers  provided  by  the  manufacturers,  together 
with  the  facilities  at  the  operator's  command  for  making  special 
matrices,  there  is  seldom  occasion  for  the  insertion  of  an  amalgam 
fining  unless  the  cavity  has  four  walls.     (See  Chapter  IV.) 

The  cavity  should  always  be  filled  to  overflowing.  Amalgam  should 
be  packed  with  steady  force  and  with  as  large  pluggers  as  are  consistent 
with  the  operation,  upon  the  orifice  of  the  cavity  and  left  until  the 


384  PROPERTIES  OF  FILLING  MATERIALS 

mass  has  become  hard  before  any  of  it  is  removed.  After  the  mass 
has  hardened  somewhat,  surplus  amalgam  should  be  removed  by  carv- 
ing toward  the  borders  with  sharp  plastic  instruments  or  excavators, 
so  that  amalgam  once  packed  along  the  margin  and  allowed  to  stiffen 
will  not  be  disturbed.  Attention  may  be  directed  to  the  fact  that  this 
can  only  be  accomplished  with  the  high  percentage  silver  alloys. 

Only  very  light  burnishing  should  be  done  at  the  time  of  insertion 
of  an  alloy  lest  the  margins  be  disturbed.  The  matrix  should  be  re- 
moved with  great  care  or  it  may  disturb  the  margins  or  even  the  bulk 
of  the  filling.  An  amalgam  filling  should  be  finished  in  the  same 
manner  as  a  gold  filling  after  it  has  "fully  set."    (See  Chapter  IV.) 

If  the  filling  be  given  its  final  finish  prior  to  reaching  its  maximum 
hardness  the  best  finish  cannot  be  obtained.  Generally  speaking, 
forty-eight  hours  is  sufficient  to  lapse  between  the  insertion  of  amal- 
gam filling  and  the  time  of  giving  its  final  finish,  although  a  week  is 
better. 

Amalgam  fillings  should  be  polished  repeatedly.  Not  more  than  a 
year  should  lapse  after  the  insertion  of  an  amalgam  filling  before  it 
should  again  have  its  margin  polished  and  burnished. 

Attention  has  been  called  to  the  fact  that  alloys  have  bulk  changes 
after  as  well  as  at  the  time  of  insertion.  This  often  causes  the  filling 
to  appear  spheroided,  tilted,  warped  or  otherwise  distorted  within  a 
year  or  two  after  insertion.  Such  fillings  should  be  ground  down  with 
small  stones  and  the  surface  again  finished. 

During  the  packing  operation  mercury  is  often  removed  from  the 
amalgam  mass  and  remains  upon  the  surface.  This  is  almost  always 
true  if  the  operator  uses  very  high  pressure  (Fig.  353),^  but  is  not 
very  marked  if  the  mass  has  been  worked  properly  and  the  excess 
mercury  removed  by  good,  firm  pressure  just  previous  to  packing,  when 
the  regular  amalgam  pluggers  are  used.  The  use  of  quick  blows,  as 
has  been  mentioned  before,  is  bad  practice,  since  it  disturbs  the 
amalgam  mass  even  when  large  pluggers  are  used.  As  fast  as  mercury 
appears  at  the  surface  during  packing  it  should  be  removed  hastily 
with  an  excavator  or  other  instrument  and  more  amalgam  inserted 
into  the  cavity. 

If  there  is  no  easy  access  to  the  cavity,  pressure  enough  to  bring 
mercury  to  the  surface  will  seldom  be  exerted.  This  is  also  the  case 
if  the  matrix  is  not  used.  It  is  quite  generally  true  that  if  there  is 
good  access,  if  a  little  mercury  is  not  removed  during  the  packing  the 
pressure  has  been  faulty.  Gold  foil,  silver  foil  and  tin  foil  have  been 
used  to  absorb  the  excess  of    mercury  appearing  at  the  surface  of 

1  Gray,  Arthur  W. 


NATURE  OF  AMALGAM 


385 


amalgam  fillings,  and  little  harm  has  probably  resulted,  although  this 
practice  cannot  be  said  to  add  to  the  qualities  of  the  amalgam.  New 
alloys  are  formed  upon  the  surface  when  anyone  of  these  materials  is 
used,  and  experiments  have  proved  that  mercury  and  one  metal  do 
not  form  an  alloy  having  the  most  desirable  qualities. 

When  tin  foil  is  used  to  absorb  mercury  appearing  at  the  surface  a 
soft  non-crystalline,  shrinking  alloy  results.  Similar  comment  may  be 
made  upon  the  use  of  the  other  materials,  gold  being  no  exception. 


100 


80 


60 


AO 


20 


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— -_J 

f 

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i 

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1 — i 

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141 


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Fig.  353. 


0  2  4  6  8 

TRITURATION  TIME  IN  MINUTE.S 

-Percentage  of  mercury  in  an  amalgam  filling  is  less  when  high  pressure  has 
been  used  to  pack  it  than  when  low  pressure  has  been  used. 


Mercury  which  has  appeared  on  the  surface  during  the  packing 
provided  the  packing  has  been  done  with  care,  should  be  removed  and 
not  used  again  without  being  redistilled.  The  affinity  of  such  mercury 
for  other  metals  is  probably  weaker,  even  though  it  remains  liquid. 

It  is  possible  that  the  presence  of  other  metals  in  mercury  may  be 
found  to  improve  its  different  qualities,  but  it  has  not  yet  been  done. 
On  the  other  hand,  mercury  which  has  been  removed  from  amalgam 
during  packing  has  almost  invariably  been  found  to  contain  more  tin 
than  other  constituents.  Dr.  Black's  later  observations  seem  to  con- 
firm this,^  but  in  the  same  chapter  he  has  stated  that  "  if  the  alloying 


1  Operative  Dentistry,  vol.  ii. 


25 


386  PROPERTIES  OF  FILLING  MATERIALS 

is  a  perfect  combination,  I  have  reason  to  believe  that  no  one  metal 
will  be  dissolved  more  than  another."  It  is  a  fact,  however,  that  when 
two  metals  are  cooled,  certain  alloys  of  these  metals  may  solidify  first 
and  a  more  fusible  alloy  of  these  metals  is  left,  and  is  known  as  the 
eutectic  alloy.  It  is  a  general  rule  that  this  defect  is  intensified  when 
four  or  five  metals  are  used,  as  is  the  case  in  the  production  of  dental 
amalgam  alloys.  With  these  facts  in  view  we  may  assume  that  an 
ingot  of  alloy  before  it  is  cut  contains  quantities  of  globules  or  strata 
of  eutectics  which  may  be  more  soluble  as  well  as  more  fusible.  Mer- 
cury which  has  had  ever  so  slight  a  contact  with  alloys  should  be 
discarded,  since  it  will  pick  up  some  of  the  alloy  and  have  its  affinity 
partially  satisfied. 

CEMENTS. 

The  term  cement  formerly  implied  a  material  which  was  used  to 
unite  two  or  more  substances.  This  has  required  that  the  uniting 
material  should  be  plastic  and  highly  adhesive  and  have  other  proper- 
ties similar  to  those  possessed  by  filling  materials.  During  recent 
years  the  possibility  of  obtaining  these  products  in  a  more  translucent 
form  has  led  to  the  development  of  several  products  known  as  cements, 
because  of  their  composition,  which  have  little  of  the  power  of  uniting 
substances.  Comparatively  recently  it  has  been  shown  that  the 
solubility  of  these  products  could  be  taken  advantage  of  by  the  intro- 
duction of  compounds  known  to  have  antiseptic  properties,  and  the 
result  has  been  the  development  of  a  class  of  cements  not  possessed 
primarily  of  adhesive  properties,  but  of  antiseptic  properties  together 
with  a  fair  degree  of  adhesive  properties. 

The  term  cement  as  it  is  used  today,  therefore,  is  a  much  broader 
term  than  it  was  formerly,  and  includes  a  variety  of  products  which 
may  be  grouped,  for  convenience,  under  three  heads,  namely,  zinc 
oxyphosphates,  copper  oxyphosphates  and  silicates.  In  each  case 
these  products  reach  the  practitioner  of  dentistry  in  the  form  of  a 
liquid  which  in  all  cases  is  an  acid  and  a  powder  which  may  be  one  or 
more  inorganic  compounds.  When  the  acid  is  placed  in  contact  with 
the  basic  material  the  result  is  the  formation  of  a  new  compound 
accompanied  by  many  of  the  usual  phenomena  that  accompany  the 
union  of  the  more  common  and  simple  acids  and  bases.  For  example, 
heat  is  generated,  strength  is  changed,  solubility  is  changed  and  the 
working  properties  are  different.  Inasmuch  as  most  of  the  cements 
now  in  use  are  the  result  of  recent  investigations,  it  is  not  possible  to 
give  the  same  amount  of  information  with  respect  to  their  properties 
and  behavior  as  is  the  case  with  amalgams.  Only  general  statements 
seemito  be  recorded. 


CEMENTS  387 

Liquid  Portion. — The  liquids  which  are  used  in  all  three  classes  of 
cements  are  compounds  of  ortho-phosphoric  acid,  aluminum  hydroxid, 
and  water.  The  following  is  the  result  of  an  analysis^  of  the  liquid  of 
one  of  the  leading  zinc  oxyphosphates : 

Orthophosphoric  acid  (85  per  cent,  acid) 79.00  per  cent. 

Aluminum  hydroxid 10.00  " 

Water 11.00 

100.00 

A  few  of  these  cements  may  be  found  to  contain  small  quantities  of 
zinc  oxid,  and  one  or  two  compounds  of  iron  probably  in  phosphate 
form,  and  still  others  a  little  copper,  also  probably  in  phosphate  form. 
Possibly  some  of  the  older  products  may  be  found  that  contain  alkaline 
modifiers  in  the  liquid,  but  it  seems  unlikely  since  practically  all 
investigators  report  the  use  of  aluminum  phosphate  as  the  best  modifier 
and  partial  neutralizer  of  the  ortho-phosphoric  acid  for  use  with 
zinc  oxid.  One  ^\Titer2  reports  the  use  of  the  oxids  of  calcium 
strontium,  beryllium,  zinc,  and  aluminum  in  solution  in  the  ortho- 
phosphoric  acid  as  the  liquid  for  the  silicates.  The  introduction  of 
new  products  containing  these  compounds  confirms  this  report.  From 
this  it  seems  that  it  is  quite  probable  that  the  composition  of  the 
liquid  for  the  silicates  may  be  changed  eventually  into  a  more  complex 
compound  than  the  one  most  desirable  for  use  in  the  formation  of  a 
zinc  oxyphosphate. 

About  the  only  generally  accepted  effect  that  is  recorded  with 
respect  to  metallic  modifiers  in  the  ortho-phosphoric  acid  is  that 
aluminum  phosphate  so  modifies  the  acid  that  less  heat  is  generated 
when  the  liquid  and  powder  are  brought  into  contact.  Improvements 
in  the  physical  properties  of  dental  cements  of  several  years  ago, 
including  the  property  of  setting  promptly  in  the  presence  of  moisture, 
are  probably  due  in  a  degree  to  the  presence  of  alummum  phosphate 
in  the  liquid. 

Much  the  same  may  be  said  in  regard  to  reliable  information  con- 
cerning modifications  of  the  acid  by  the  addition  of  water.  Ortho- 
phosphoric  acid  is  ordinarily  known  as  a  colorless,  odorless  syrup, 
with  a  specific  gravity  of  1.7  and  containing  from  83  per  cent,  to  85 
per  cent,  of  phosphoric  acid  (H3PO4). 

In  chemistry,  however,  it  is  known  as  a  translucent,  very  deliques- 
cent soft  solid,  with  a  specific  gravity  of  1 .88,  containing  nothing  else. 

It  should  be  obvious,  therefore,  that  the  100  per  cent,  acid  is  not 
in  a  form  suitable  for  combination  with  a  prepared  powder.     The 

1  Ward,  Marcus  L.  and  McCormick,  R.  M.:  Jour.  Nat.  Dent.  Assn.,  1915. 

2  Voght,  C.  C:  Jour.  Nat.  Dent.  Assn.,  April,  1918. 


PROPERTIES  OF  FILLING  MATERIALS 

85  per  cent,  acid  is  in  a  much  more  favorable  form,  but  it  has  been 
proved  less  desirable  from  many  standpoints  than  a  still  more  dilute 
and  partially  neutralized  acid  such  as  previously  given  for  use  in  the 
formation  of  a  zinc  oxyphosphate.  The  acid  with  a  greater  dilution 
not  only  acts  as  a  better  solvent,  but  the  water  apparently  plays  an 
important  part  in  the  chemical  reactions  with  the  powder  resulting  in 
beneficial  changes  in  physical  properties  of  the  product  after  it  has  set. 
With  certain  cement  powders  the  addition  of  a  small  percentage  of 
water  to  the  phosphoric  acid  will  hasten  the  setting  while  with  others 
the  subtraction  of  water  will  retard  the  setting.  This  should  be  kept 
in  mind  as  well  as  the  fact  that  phosphoric  acid  is  deliquescent,  for  a 
cement  liquid  may  be  nicely  balanced  with  respect  to  water  content 
when  it  leaves  the  manufacturers'  hands  and  later  become  unbalanced 
upon  exposure  to  the  air,  with  marked  changes  in  properties.  An 
atmosphere  such  as  exists  in  a  steam-heated  room  in  the  winter  months 
is  usually  dry.  If  a  bottle  of  cement  liquid  be  left  exposed  to  such  an 
atmosphere  it  may  lose  from  10  per  cent,  to  20  per  cent,  of  the  water 
content.  If,  on  the  other  hand,  the  bottle  be  left  exposed  in  a  room" 
that  is  warm  and  saturated  with  moisture,  such  as  frequently  happens 
in  rainy  weather,  the  liquid  may  take  up  as  much  as  from  1  per  cent, 
to  4  per  cent,  of  water.  Such  changes  have  been  shown  to  produce 
marked  changes  in  the  properties  of  the  cement,  and  should,  therefore, 
be  guarded  against  in  every  way  possible. 

Powder  Portion. — Zinc-oxyphosphates. — For  many  years  zinc  oxid 
has  been  regarded  the  most  suitable  single  constituent  to  combine  with 
modified  phosphoric  acid  to  produce  a  dental  cement.  Earliest  obser- 
vations, however,  showed  that  unmodified  zinc  oxid  did  not  yield  a 
cement  that  possessed  as  many  desirable  properties  as  zinc  oxid  which 
was  modified  by  either  calcination  of  the  zinc  oxid  or  combining  some 
other  compound  with  it.  When  unmodified  zinc  oxid  combines  with 
phosphoric  acid,  or  the  prepared  phosphoric  acids  now  in  use,  the  mass 
sets  too  rapidly,  making  it  impossible  to  make  a  smooth  mass.  The 
mass  is  also  less  adhesive,  weaker  and  more  soluble.  Many  of  the 
earlier  cements  were  made  from  plain  zinc  oxid,  slightly  pigmented,  to 
produce  different  shades,  though  they  failed  to  meet  the  demands 
placed  upon  these  products.  As  the  cements  have  been  developed 
to  meet  more  of  the  demands  on  these  products,  more  and  more 
modification  of  the  zinc  oxid  has  taken  place.  Among  the  .first  modi- 
fications to  be  adopted  was  calcination  of  the  zinc  oxid.  As  zinc 
oxid  is  heated  it  becomes  fused  and  takes  on  the  appearance  of 
powdered  glass  or  powdered  silica,  turns  slightly  yellow  in  color,  is  less 
soluble,  becomes  much  less  flocculent  and  reacts  with  phosphoric  acid 
much  less  rapidly.     Its  chemical  composition  does  not  change  but  it§ 


CEMENTS 


389 


physical  composition  is  markedly  different,  and  when  combined  with 
phosphoric  acid  or  a  prepared  phosphoric  acid  the  result  is  quite 
different  than  when  used  unmodified.  Another  method  of  modifying 
zinc  oxid  for  use  in  dental  cements  consists  of  dissolving  zinc  oxid  in 
nitric  acid  and  subsequently  evaporating  to  dryness.  The  zinc  oxid 
thus  produced  from  the  nitrate  is  quite  similar  to  zinc  oxid 
prepared  by  calcination,  except  that  in  this  instance  the  particles  of 
zinc  oxid  are  in  a  definite  form.  If  the  nitration  process  has  been 
carried  out  carefully,  practically  every  particle  seems  to  be  of  the  same 

1.  Heating  or  nitration  practiced  by  all  manufacturers. 

2.  Fineness  of  comminution  practiced  by  all  manufacturers. 

Cement  pow-  f  Bi203    (used    by  Caulk,  Ames,  Smith 

der    is    zinc  (a)   To  improve  I       and  Fleck). 

oxid     (ZnO)  properties    |  MgO    (used    by  Caulk,  White,  Smith 

modified  by  I      and  Fleck). 

(b)   To  color  the  |  MnOo  (black). 
powder        \Fe203(red). 


3.  Addition  of 
other  com- 
pounds 


(c) 


To  add  an- 
tiseptic 
properties 


f  CuO  (black) 

Ci  (i 

CuaO  (red) 

CU2I2  (white) 

CuSiOs  (greenish- 
blue) 

AgCl  (white) 

AgsPOi  (yellow). 
Both  turn  black 
on  exposure  to 
light. 


99%  Ames. 
25%  Caulk. 
25%  Fleck. 

8%  Caulk. 

2%  Caulk. 

2%  Smith. 

2%  S.  S. 
2%  S.  S. 


White. 
White. 


size  and  shape,  while  with  the  calcination  process  the  particles  may  be 
of  all  sizes  and  shapes.  As  shown  in  the  foregoing  chart,  both  of  these 
processes  are  adaptable  to  practically  all  manufacturers'  products 
which,  as  a  result  of  the  combination  of  zinc  oxid  and  phosphoric  acid, 
are  known  as  zinc  oxyphosphates. 

By  referring  to  the  chart  on  cement  powders  it  may  be  observed  also 
that  zinc  oxid  may  be  modified  in  a  third  way,  namely,  by  the  addition 
of  other  compounds.  The  first  class  of  compounds  is  added  for  the 
purpose  of  improving  the  color,  the  second  to  change  the  color  and  the 
third  to  add  antiseptic  properties. 

The  principal  compounds  that  have  been  found  to  be  desirable 
in  modifying  zinc  oxid  for  cement  powders  are  bismuth  trioxid  and 
magnesium  dioxid.  Just  what  part  these  compounds  play  in  the 
cement-making  process  has  not  been  recorded  and  the  author  has  done 
comparatively  little  work  on  them.^ 

The  limited  work  done  by  the  author  on  the  influence  of  bismuth 
trioxid  tends  to  show  that  it  is  added  principally  for  the  purpose 


1  Ward,  Marcus  L.,  and  McCormick,  R.  M.:  Jour.  Nat.  Dent.  Assn.,  November,  1915. 


390  PROPERTIES  OF  FILLING  MATERIALS 

of  making  a  smoother  mass.  It  does  not  appear  that  the  bismuth 
compound  sets  when  combined  with  a  prepared  phosphoric  acid  but 
produces  a  smooth,  oily  appearing  mass,  which  remains  in  a  plastic 
state.  It  would  seem  from  this  that  bismuth  trioxid  exerted  a  retard- 
ing influence  upon  the  rate  of  setting.  While  nothing  definite  is 
recorded  with  respect  to  the  influence  of  magnesium  dioxid  upon  the 
cement  mass,  it  is  to  be  expected  that  it  plays  a  very  important  part 
in  the  hydration  process,  for  its  behavior  alone  and  in  combination 
with  other  compounds  is  well  known. 

Examination  of  the  various  products  in  the  market  reveals  that  in 
some  instances  something  has  been  added  to  the  zinc  oxid,  magnesium 
dioxid,  bismuth  trioxid  compound  to  color  it.  Zinc  oxid  is  white  before 
it  has  been  heated  or  nitrated  and  yellow  after  either  treatment. 
Bismuth  trioxid  is  a  citron  yellow  compound  and  magnesium  dioxid 
is  a  white  compound.  When  the  three  are  combined  it  is  obvious  that 
the  result  is  likely  to  be  white  or  yellow  in  proportion  to  the  amount 
of  calcination  given  to  the  zinc  oxid;  the  amount  of  heat  applied  to 
the  mixture  of  bismuth  trioxid,  zinc  oxid,  and  magnesium  dioxid;  and. 
the  percentage  of  bismuth  trioxid  used. 

The  white  and  yellow  powders  thus  produced  may  be  converted 
into  various  shades  of  gray,  including  greenish  gray,  by  the  addition 
of  very  small  quantities  of  a  black  compound.  The  author  has  repeat- 
edly found  one  manufacturer's  product  to  contain  manganese  dioxid 
in  the  gray  powders  and  has  found  upon  experiment  that  as  low  a 
percentage  as  0.20  of  this  black  compound  will  produce  the  shades  of 
gray  and  greenish  gray. 

The  author  has  also  repeatedly  found  some  of  the  brown  and  reddish- 
brown  powders  to  be  colored  with  ferric  oxid.  This  appears  to  be  the 
only  other  coloring  matter  than  manganese  dioxid  necessary  to  produce 
the  various  shades  of  zinc  oxyphosphates  now  in  the  market,  which 
are  at  present  limited  to  shades  white,  yellow,  gray  and  brown. 

Copper. — Oxyphosphates  (Antiseptic  Cements). — ^The  third  class  of 
compounds  added  to  the  zinc  oxid  is  for  the  purpose  of  adding  anti- 
septic properties,  and,  as  may  be  noted  from  the  chart,  is  limited  at 
present  to  compounds  of  copper  and  silver,  both  of  which,  for  a  long 
time,  have  been  known  to  possess  antiseptic  properties  largely  in  pro- 
portion to  the  percentage  of  the  copper  or  silver  compound  added. 
Four  compounds  of  copper  have  been  found  in  present  products;  one 
is  black  (cupric  oxid),  one  red  (cuprous  oxid),  one  white  (cuprous 
iodid)  and  one  greenish-blue  (cupric  silicate).  Recently  two  com- 
pounds of  silver  have  been  introduced,  one  of  which  is  white  (silver 
chlorid)  and  one  yellow  (silver  phosphate) .  With  the  exception  of  the 
first  product  marketed  by  the  W.  V.  B.  Ames  Company  containing 


CEMENTS  391 

practically  all  cupric  oxid,  all  of  the  leading  cement  powders  in  the 
market  which  have  compounds  of  copper  or  silver  added  for  the  pur- 
pose of  adding  antiseptic  properties  are  modifications  of  the  regular 
cement  powders.  The  first  product  shown  contains  cupric  oxid,  with 
a  very  small  quantity  of  a  compound  of  cobalt,  and  is  placed  in  the 
group  of  modifiers  of  zinc  oxid  only  for  the  purpose  of  showing  at  a 
glance  those  cement  powders  which  have  varying  degrees  of  anti- 
sepsis. By  the  total  elimination  of  the  zinc  oxid,  bismuth  trioxid,  and 
magnesium  dioxid  the  maker  of  this  product  has  a  material  which 
represents  the  maximum  in  germicidal  efficiency.  All  the  other 
products  shown  may  be  treated  as  ordinary  cement  powders  which 
have  had  added  to  them  a  copper  or  silver  compound  for  the  purpose 
of  making  them  more  antiseptic  than  the  ordinary  cement  powder  is. 
It  may  be  noted  that  these  products  have  been  used  in  quantities 
ranging  from  about  2  per  cent,  to  about  25  per  cent.  It  may  be  noted 
also  that  the  compounds  of  copper  and  silver,  in  the  quantities  used, 
result  in  the  production  of  three  classes  of  cement  powders  with  respect 
to  color,  one  black,  one  red  and  one  light. 

The  class  of  light  copper  cements  may  contain  any  one  of  the  last 
four  compounds  shown  in  the  chart  on  cement  powders.  This  class  of 
cements  is  not  light  in  color  on  account  of  the  original  color  of  the 
copper  or  silver  compound,  but  because  there  is  not  a  sufficient  quan- 
tity of  the  silver  or  copper  compound  contained  in  this  class  of  anti- 
septic cements  to  turn  the  cement  mass  into  a  dark  color.  Both  of  the 
copper  and  both  of  the  silver  compounds  shown  which,  when  intro- 
duced into  a  cement  powder,  are  comparatively  light  in  color,  are 
capable  of  turning  almost,  if  not  quite,  black  upon  exposure.  The 
only  way,  therefore,  that  is  known  by  which  a  class  of  copper  or  silver 
antiseptic  cements  may  be  made  is  to  keep  the  percentage  of  copper  or 
silver  compound  so  low  that  when  they  have  turned  dark  they  will 
not  make  the  mass  very  dark. 

It  seems  that  with  one  or  two  exceptions,  compounds  of  copper  and 
silver  are  added  to  the  ordinary  cement  powders  in  quantities  ranging 
from  about  2  per  cent,  to  about  25  per  cent.,  resulting  in  the  production 
of  three  classes  of  compounds  with  respect  to  color.  Because  the  ques- 
tion of  antisepsis  is  of  principal  importance,  and  because  of  the  more 
general  use  of  compounds  of  copper  than  of  silver  for  the  purpose  of 
obtaining  antisepsis,  these  products  have  been  designated  as  copper 
oxyphosphates  to  distinguish  them  from  the  ordinary  cements  known 
as  zinc  oxyphosphates.  The  general  practitioner  of  dentistry  has  fur- 
nished to  him  by  the  manufacturers  of  dental  products  these  three 
colors  of  copper  oxyphosphates,  some  of  which  have  very  little  more 
antiseptic  value  than  the  ordinary  cement^  while  others  have  decidedly 


392 


PROPERTIES  OF  FILLING  MATERIALS 


more,  depending  upon  the  quantity  of  copper  or  silver  present  and  the 
solubihty  of  the  cement  after  it  has  hardened.  It  is  to  be  expected 
that  the  dental  profession  will  undertake  to  determine  what  degree  of 
antisepsis  is  necessary  in  these  products  in  order  to  maintain  a  satis- 
factorily hygienic  condition  on,  and  adjacent  to,  many  of  the  restor- 
ations retained  in  the  mouth  by  cementation.  At  the  present  time, 
however,  practically  all  that  is  recorded  regarding  antiseptic  cements  is 
by  the  manufacturers  of  dental  materials,  and  is  so  conflicting  in  sub- 
stance^ that  it  is  of  little  value  to  the  average  general  practitioner  of 
dentistry. 

The  first  of  the  articles,^  3  4  56  ^^s  written  in  1914  by  W.  V.  B. 
Ames,  who  is  the  maker  of  the  first  product  shown  in  the  chart.  This 
product  differs  from  the  others  by  having  its  germicidal  agent  the 
principal  cement-making  material.  In  this  article  the  writer  speaks  of 
the  impregnation  of  a  cement  powder  with  cuprous  iodid  as  "  a  senseless 
temporary  expedient,"  and  designates  his  product  as  the  "real  oxy- 
phosphate."  Since  the  appearance  of  this  article  several  others  have 
appeared  apparently,  in  most  instances,  as  a  defence  of  the  procedure 
which  Ames  condemns.  Among  other  things,  Poetschke  speaks  very 
highly  of  cuprous  iodid,  but  does  not  say  that  the  product  marketed 
by  Ames  is  not  more  antiseptic.  Smirnow's  work  leads  to  the  con- 
clusion that  cuprous  oxid  is  the  most  germicidal,  while  Bacon's  work 
implies  that  all  of  the  copper  cements  are  sufficiently  germicidal. 
Quite  recently  the  S.  S.  White  Dental  Manufacturing  Company  has 
published  a  statement  that  their  experience  with  these  products  has 
caused  them  to  eliminate  compounds  of  copper  from  consideration. 

This  company  has  sent  out  some  literature,  with  the  following  chart, 
to  show  the  reason  for  the  use  of  silver  compounds  instead  of  the  more 
generally  used  copper  compounds: 


O  --                              V                                                  X 

X                                                * 

Comparative  tooth 

and     cement     dis- 

Comparative 

Necessary  for 

coloration  in   effi- 

germicidal 

eflaciency. 

cient  percentage 

strength. 

Per  cent. 

Natural  color. 

strength. 

Copper  oxid  (black) 

100 

50 

Jet  black 

100 

Copper  oxid  (red) 

100 

50 

Red 

100 

Copper  silicate 

100 

30 

Green  white 

40 

Copper  iodid  . 

350 

30 

Light  brown 

35 

Silver  chlorid 

3200 

2 

White 

0 

Silver  phosphate 

.      10400 

1  to  2 

Light  gray 

slight 

Paul  Poetschke,^  a  chemist  for  the  L.  D.  Caulk  Company,  states 
that  his  results  show  that  silver  cements  are  not  as  efficient  as  most 

1  The  reader  is  referred  to  an  article  on  this  subject  in  the  Dental  Review  for  August, 
1916,  Marcus  L.  Ward. 

2  Ames,  W.  V.  B.:  Dental  Review,  1914. 

*  Poetschke,  Paul:  Jour.  Indus,  and  Engin.  Chem.,  1915. 

*  Smirnow,  M.  R. :  Dental  Cosmos,  1915. 
6  Bacon,  Raymond  F.:  Ibid,  1916. 

6  Poetschke,  Paul:  Ibid.,  1916.  '  Caulk  Scientific  Bulletin  No,  1. 


CEMENTS 


393 


of  the  copper  cements,  and  claims  to  be  able  to  obtain  an  efficiency  of 
only  72  per  cent,  to  80  per  cent,  after  fifteen  minutes'  exposure.  In 
the  same  contribution  and  in  the  following  chart^  he  shows  that  an 
efficiency  is  obtained  with  the  use  of  copper  cements  as  high  as  100 
in  the  same  length  of  exposure. 


RECENT    GERMICIDAL    EFFICIENCY    TESTS    OF  SILVER    CEMENTS, 


Sample. 
S.  S.  White  silver  cement  A 
S.  S.  White  silver  cement  B 
S.  S.  White  zinc  cement 


No.  of  living  bac- 
teria per  c.c.  just 
before  addition  of 
1  gram  of  sample. 

After  exposure 
of    15    minutes. 

Per  cent,  germicida 

efficiency  after 

exposure  of 

15  minutes. 

21,110,000 

5,830,000 

72.3 

28,300,000 

5,380,000 

80.9 

21,510,000 

21,450,000 

0.3 

GERMICIDAL    EFFICIENCY,    CRUSHING    STRENGTH,    AND    RETROGRESSION 
IN  STRENGTH   IN  SALIVA. 


Sample. 

Percentage  of  germicidal  efficiency  Crushing  strength  in  saliva 
after  exposure  of                            after  exposure  of 
5  min.         15  min.          1  hour.       1  day.       7  days.      28  days. 

Percentage 

retrogression 

in  strength 

in  saliva. 

1         .       . 

.      .        0.0 

66.6           83.3 

970           903 

797 

17.8 

2        .      . 

.      .      99.4 

100.0         100.0 

595            755 

833 

0.0 

3       .      . 

.       .      97.1 

100.0         100.0 

788           800 

918 

0.0 

4        .      . 

.      .      96.0 

100.0         100.0 

935         1000 

788 

21.2 

5       .      . 

.      .      10.0 

96.0           98.0 

280           270 

0 

100.0 

6       .      . 

.      .        0.0 

96.4           97.1 

530           570 

705 

0.0 

These  two  charts  are  quite  indicative  of  the  condition  of  the  dental 
literature  with  respect  to  antiseptic  cements.  Obviously  they  do  not 
agree,  nor  do  they  mention  the  question  of  relative  solubility.  The 
authors  of  both  charts  refer  rather  briefly  to  solubility  in  their  con- 
tributions but  do  not  include  data  on  this  property.  Without  these 
data  it  is  very  difficult  to  draw  conclusions  of  value  in  the  practice  of 
dentistry. 

It  seems  to  be  generally  acknowledged  that  all  cements  are  antiseptic 
while  in  the  plastic  state,  due  to  free  phosphoric  acid  and  acid  phos- 
phates. The  free  phosphoric  acid  and  acid  phosphates  are  soon  fixed 
through  the  chemical  combination  with  the  basic  constituents  of  the 
powder,  and  through  occlusion  in  the  set  mass  of  cement.  This  tran- 
sition from  the  plastic  to  the  hardened  state  is  of  short  duration,  and 
coincident  with  it  there  is  a  marked  change  in  the  physical  and  chemical 
properties  of  the  cement. 

It  should  be  obvious,  therefore,  that  if  prolonged  germicidal  action 
is  to  obtain  the  hardened  cement  and  not  the  plastic  cement  must 
furnish  it.  If  the  hardened  cement  were  wholly  insoluble  there  would 
be  no  germicidal  action  even  though  it  contained  large  quantities  of 


1  Jour.  Engin.  Chem.,  No.  4,  viii,  308. 


394  PROPERTIES  OF  FILLING  MATERIALS 

germicidal  compounds.  On  the  other  hand  if  the  cement  be  somewhat 
soluble  the  germicidal  compounds  will  be  slowly  released.  If  two 
cements  possess  equal  solubility  germicidal  efficiency  will  depend  upon 
the  presence  of  potent  germicides,  but  if  they  have  unequal  solubility 
the  one  with  the  less  solubility  will  be  less  efficient  as  a  germicide.  The 
question  that  at  once  arises  in  the  mind  of  the  practitioner  of  dentistry 
is  which  is  the  better  of  the  two.  No  definite  answer  can  be  made 
until  more  definite  knowledge  regarding  the  degree  of  germicidal 
efficiency  necessary  under  the  varying  mouth  conditions  is  known. 
In  the  light  of  our  present  knowledge  of  the  far-reaching  effects  of 
pericemental  infections,  and  in  view  of  the  demands  now  being  made 
for  their  prevention,  it  seems  that  whenever  there  is  a  question  between 
solubility  and  germicidal  efficiency  a  proper  degree  of  germicidal 
efficiency  should  be  given  the  preference  if  the  cement  is  located  where 
it  is  in  contact  with  susceptible  tissue.  This  question,  however,  is  not 
likely  to  be  of  much  interest  to  the  practitioner  of  dentistry  for  the 
reason  that  most  manufacturers  prefer  to  increase  the  quantity  of 
germicidal  compound  or  select  a  more  potent  one  than  to  increase 
solubility  for  the  purpose  of  making  their  cement  more  germicidal. 
Some  manufacturers  make  two  or  three  antiseptic  cements  so  that  a 
given  solubility  may  be  preserved  and  at  the  same  time  have  a  variety 
of  germicidal  efficiencies. 

It  is  to  be  hoped  that  in  the  near  future  more  data  will  be  available 
on  what  constitutes  the  proper  degree  of  germicidal  efficiency,  for,  as 
may  be  seen,  the  chart  shows  a  variety  of  opinions  expressed  in  the 
manufacture  of  a  variety  of  products  with  no  information  as  to  the 
places  where  they  are  indicated.  It  seems  safe  to  prophesy  a  very 
limited  use  of  the  copper  cements  containing  only  about  2  per  cent,  of 
a  copper  compound  (light  copper  cements).  As  a  class  they  seem  not 
much  more  germicidal  than  the  ordinary  cements  for  general  use. 
The  manufacturers  of  some  of  these  products  claim  that  they  are 
sufficiently  germicidal  and  that  they  will  not  discolor  in  the  mouth. 
The  claim  of  sufficient  germicidal  efficiency  is  not  based  upon  proof 
that  is  known  to  be  reliable.  The  claim  that  they  will  not  discolor  in 
the  mouth  is  perfectly  justifiable  because  any  light  compound  of  copper 
when  oxidized  into  cupric  or  cuprous  form,  thus  becoming  black  or  red, 
will  not  discolor  cement  or  tooth  appreciably  when  used  in  only  2 
per  cent. 

One  manufacturer  furnishes  a  small  bottle  of  cement  powder  con- 
taining 10  per  cent,  of  cuprous  iodid  with  the  ordinary  product  of  the 
company,  Instructions  accompany  the  package  advising  the  use  of 
as  much  of  the  cuprous  iodid  with  the  ordinary  cement  powder  as  is 
thought  necessary.    This  allows  the  practitioner  of  dentistry  to  obtain 


CEMENTS  395 

any  percentage  of  cuprous  iodid  up  to  ten,  and,  in  principle,  appears 
to  be  more  in  harmony  with  modern  therapeutics  than  the  adoption  of 
fixed  percentages. 

It  may  be  possible,  however,  to  determine  upon  fixed  percentages 
that  will  meet  the  demands  of  average  cases.  It  seems  at  this  time  that 
if  this  course  be  adopted  it  will  not  be  necessary  to  manufacture 
products  containing  less  than  5  per  cent,  of  cuprous  iodid  or  its  equiv- 
alent, for  as  the  subject  is  studied,  more  and  more  evidence  accumu- 
lates to  show  that  the  light  copper  cements  containing  about  2  per  cent, 
of  copper  are  comparatively  inefficient  as  germicides. 

Silicate  Cements. — Comparatively  recent  improvements  in  the 
zinc  oxyphosphates  and  the  copper  oxyphosphates  have  stimulated 
investigation  with  the  use  of  compounds  which  would  yield  products 
which  were  more  translucent  than  were  obtainable  with  zinc.  The 
efforts  of  the  manufacturers  have  been  directed  toward  the  development 
of  a  product  that  would  have  most  of  the  properties  of  the  zinc  cement 
and  at  the  same  time  possess  the  additional  property  of  translucency. 
At  the  present  stage  of  these  efforts  such  materials  as  silicon  dioxid, 
calcium  oxid,  aluminum  oxid  are  used  to  form  a  powder  which,  when 
mixed  with  a  liquid  composed  of  phosphoric  acid  and  water  and  metallic 
oxids,  sets  in  much  the  same  manner  as  the  zinc  cements. 

The  general  use  of  silicon  dioxid  and  the  similarity  between  these 
products  in  translucency  has  apparently  led  to  the  adoption  of  the 
name  silicate  cements. 

On  account  of  the  recent  development  of  these  products  to  a  place 
where  they  were  suitable  for  a  trial  in  practice,  little  reliable  informa- 
tion is  available.  In  fact,  only  two  writers,^  ^  have  attempted  to  reveal 
the  information  that  is  possessed  by  the  manufacturers.  A  few  others 
have  written  at  some  length,  but  have  revealed  little. 

Voght  claims  that  in  addition  to  the  constituents  mentioned  it  is 
necessary  to  add  some  additional  components,  such  as  fluorids,  in 
order  to  aid  in  fusing  at  a  low  enough  temperature  to  keep  the  alumi- 
num oxid  in  such  a  condition  that  it  is  chemically  active  while  the 
mass  remains  translucent. 

He  also  states  that  the  oxids  that  are  used  in  solution  in  the  phos- 
phoric acid  and  water  are  aluminum,  beryllium,  calcium  and  zinc.  It 
is  assumed  that  not  all  of  these  oxids  are  used  in  any  one  liquid.  Pro- 
bably one  or  two  are  used,  making  the  liquid  not  much  different  from 
the  liquids  used  for  the  production  of  the  zinc  cements,  so  far  as  con- 
stituents are  concerned.  The  same  writer  states  that  non-metallic 
oxids  or  acid  anhydrids,  as,  for  example,  the  oxids   of   phosphorus, 

1  Voght,  C.  C:  Jour.  Nat.  Dent.  Assn.,  vol.  v. 

-  Poetschke,  Paul:  Jour.  Indus,  and  Engin.  Chem.,  April,  1916. 


396  PROPERTIES  OF  FILLING  MATERIALS 

boron  and  titanium,  may  also  be  present  in  the  powder  portion.  From 
this  it  may  be  seen  that  these  products  are  very  complex  and  little 
understood,  or  that  those  in  possession  of  information  are  not  inclined 
to  reveal  it.  In  either  case  it  does  not  seem  possible  to  discuss  the 
subject  except  in  a  very  limited  way. 

It  seems  to  be  common  clinical  observation  that  the  silicate  cements 
are  more  translucent  and  more  insoluble  than  the  zinc  cements,  and 
that,  as  a  class,  they  are  less  adhesive,  less  tough  and  less  hydraulic. 

Some  Properties  Common  to  all  Cements. — It  should  be  obvious 
that  each  class  of  cements  has  one  or  more  properties  developed  to 
a  greater  degree  than  other  classes  which  are  intended  to  be  used 
for  other  purposes.  For  example,  a  zinc  oxyphosphate  that  was  not 
quite  adhesive  and  possessed  of  a  high  degree  of  hydraulicity  would 
not  be  generally  accepted  for  the  reason  that  such  cements  are  used,  as 
a  rule,  for  the  retention  of  inlays,  crowns,  bridges,  bands,  etc.  In 
accordance  with  the  needs,  the  manufacturers  develop  these  two 
properties  to  a  higher  degree  than  they  do  with  the  other  cements. 
It  should  be  equally  obvious  that  a  copper  oxyphosphate  or  silver 
oxyphosphate  must  have  a  higher  antiseptic  value  than  other  cements 
or  there  would  be  little  reason  for  their  manufacture.  Likewise,  sili- 
cate cements  should  be  more  translucent  than  other  cements  or  there 
would  be  little  demand  for  them. 

Among  the  properties  which  are  most  desired  in  any  dental  cement 
are:  insolubility,  constancy  of  volume,  high  resistance  to  stresses, 
hydraulicity,  adhesion,  density,  non-porosity.  In  addition  it  has  been 
pointed  out  that  some  cases  demand  a  cement  which  is  antiseptic  and 
some  demand  one  that  is  translucent. 

Among  other  properties  which  are  usually  taken  into  consideration 
by  the  manufacturer  are :  heat  generated  during  and  subsequent  to  the 
insertion  of  the  cement  into  the  tooth,  toxic  action  on  the  pulp,  rate  of 
setting  and  permanency  of  color. 

It  does  not  appear  that  present  knowledge  of  chemistry  and  physics 
will  permit  the  production  of  a  cement  which  possesses  all  of  these 
properties  developed  to  a  degree  desired  by  dentists,  so  the  manu- 
facturers have  done  the  best  possible  to  meet  all  the  demands  placed 
upon  these  products  rather  than  to  develop  one  or  two  properties 
to  the  exclusion  of  others.  If  it  were  not  quite  necessary  to  have  dental 
cements  of  certain  colors  and  have  them  set  at  a  given  rate  it  might  be 
possible  to  produce  a  dental  cement  that  is  as  insoluble  as  some  of  the 
commercial  cements.  To  ignore  color  and  rate  of  setting  would  render 
some  cements  worthless  in  the  practice  of  dentistry.  The  situation  is 
much  the  same  regarding  other  properties.  A  dental  cement  must  pos- 
sess properties  which  are  acceptable  from  several  standpoints  and  will 


CEMENTS  397 

not  be  useful  if  the  varied  demands  of  dentists  upon  these  products 
have  not  been  taken  into  consideration  by  those  who  produce  them. 

Solubility. — One  of  the  properties  which  all  cements  should  possess 
is  a  reasonable  degree  of  insolubility,  for  in  few  instances  in  the  practice 
of  dentistry  is  it  practicable  to  completely  prevent  these  products  from 
coming  into  contact  with  the  saliva.  At  the  present  time  no  reliable 
standard  of  insolubility  has  been  established  except  that  of  clinical 
observation.  Dentists  usually  are  able  to  observe  whether  cements 
remain  in  position  a  reasonable  length  of  time  without  loss  of  mass. 
In  comparison  with  metallic  fillings  they  are  seen  to  be  the  more  sol- 
uble of  the  two.  In  comparison  with  one  another  cements  are  seen  to 
be  more  soluble  in  some  cases  than  in  others.  This  may  be  due  to  the 
composition  and  manufacture  of  the  cement,  or  to  the  greater  solvent 
action  of  the  saliva  in  some  cases  than  in  others,  or  to  the  manipula- 
tion given  the  cement. 

A  cement  which  has  been  so  manufactured  that  it  is  more  soluble 
than  another  when  used  under  the  most  favorable  conditions  cannot 
be  improved  much  by  the  manipulation,  nor  will  the  media  in  which 
it  is  placed  improve  its  inherent  solubility. 

A  cement  which  is  known  to  be  one  of  the  most  insoluble  may  show 
much  more  loss  of  material  in  some  cases  than  others,  even  though 
the  abrasion  on  the  two  has  been  equal.  This  is  due  to  differences  in 
the  solvent  power  of  the  saliva.  More  than  a  decade  ago  Joseph  Head^ 
pointed  out  the  restraining  power  of  saliva  upon  lactic  acid  and  other 
substances.  He  showed  that  a  1  to  500  lactic  acid  and  water  may  in 
some  instances  turn  tooth  enamel  white  in  one-half  an  hour,  while  in 
other  cases  it  may  not  turn  it  white  in  several  weeks  and  yet  the  latter 
solution  would  turn  blue  litmus  red  and  possess  an  acid  taste.  He  also 
showed  that  the  saliva  of  an  individual  may  change  from  time  to  time. 

Dr.  Kirk^  has  called  attention  to  the  possibility  of  mucin  being  a 
protective  element  in  the  saliva  which  prevents  the  action  of  dilute 
acids  upon  the  teeth.  He  has  also  called  attention  to  a  quite  analogous 
phenomenon,  in  which  he  showed  that  both  acid  and  basic  sodium 
phosphate  may  exist  in  the  same  saliva  and  not  be  neutralized  by  each 
other. 

With  further  reference  to  the  solubility  of  cements  it  should  be 
remembered  that  debris  and  food  particles  may  restrain  the  action  of 
acids  in  much  the  same  manner  as  mucin  or  other  constituents  of  saliva. 

Inasmuch  as  calcination  or  nitration  of  zinc  oxid  lessens  its  solubility, 
it  is  natural  to  expect  the  yellow  cements  to  be  more  insoluble  than 
the  very  light  ones.     It  is  possible,  however,  to  make  a  very  light 

1  Pental  Cosmos,  1908.  2  Jbjd,,  Hi,  735. 


398  PROPERTIES  OF  FILLING  MATERIALS 

cement  yellow  by  heating  it  with  the  bismuth-tri-oxid  that  is  often 
used  which  would  not  lessen  the  solubility.  The  average  yellow  cement, 
however,  is  not  made  this  color  this  way,  which  makes  it  generally 
safer  to  choose  the  yellow  cements  where  this  color  is  not  objectionable 
and  the  maximum  insolubility  is  desirable. 

Furthermore,  cements  which  have  a  given  solubility  when  tested  by 
the  manufacturer  may  show  a  different  solubility  test  when  tested  by 
someone  else  if  the  instructions  of  the  maker  have  not  been  followed 
closely.  In  fact,  such  influences  as  temperature  and  humidity  which 
are  usually  neglected  by  those  inexperienced  in  testing  these  products 
are  likely  to  mislead  the  novice.  Fully  as  important  as  these,  however, 
is  the  consistency  of  the  mix.  If  the  manufacturer  of  one  of  these  pro- 
ducts has  after  long  experimentation  so  balanced  his  product  that  there 
is  a  minimum  of  solubility,  it  is  likely  that  another  consistency  of  the 
mass  than  the  one  used  by  the  manufacturer  will  show  another  rate  of 
solubility.  With  some  cements  this  is  known  to  be  the  case.  With  all 
others  it  is  probable.  A  hardened  mass  of  cement  mixed  to  such  a  con- 
sistency that  it  may  be  handled  with  the  fingers  without  sticking  to 
them  contains  many  granules  of  zinc  oxid  which  have  been  attacked 
only  slightl}^,  if  at  all,  by  the  liquid.  As  a  rule  such  a  mass  possesses 
not  only  quite  a  different  solubility  than  a  hardened  mass  which  was 
mixed  so  that  it  would  drop  easily  from  the  spatula,  but  also  different 
strength,  volume  change,  adhesion,  etc.  Solubility,  therefore,  is 
dependent,  to  some  extent,  upon  the  consistency  of  the  mass.  (See 
Mixing  Cements.) 

From  these  data  it  does  not  seem  possible  to  establish  a  standard  by 
which  the  solubility  of  cements  can  be  determined  in  advance  of 
clinical  use  for  the  reason  that  there  are  too  many  variables.  Labora- 
tory tests  furnish  excellent  guides  to  what  may  be  expected  in  prac- 
tice if  conducted  under  fixed  conditions,  but  if  they  are  not  conducted 
under  fixed  conditions  they  are  often  worthless. 

Volume  Changes. — ^The  better  cements  are  tested  for  volumetric 
change  at  the  time  of  making  the  mix  and  during  the  setting.  On 
account  of  the  energetic  action  between  the  ordinary  cement  liquid 
and  powder  it  is  very  difficult  to  learn  the  first  movement  that  takes 
place  during  the  initial  stages  of  setting.  With  some  of  these  products 
the  first  movement  will  have  nearly  all  taken  place  before  a  contact 
can  be  made  to  determine  the  amount  of  it. 

It  is  the  aim  of  the  manufacturer  of  these  products  to  have  them  as 
free  from  volume  change  as  possible.  If  the  directions  that  the  better 
manufacturers  place  upon  the  packages  are  followed  the  volume  change 
that  occurs  subsequent  to  insertion  will  not  be  detrimental  to  the 
products.    If,  however,  no  attention  is  given  to  them  there  may  be  a 


CEMENTS  399 

marked  change  in  volume,  thereby  making  operations  in  which  cements 
are  used  of  less  value  than  they  would  otherwise  be.  For  example  a 
cement  which  will  shrink  markedly  when  kept  perfectly  dry  may 
expand  very  much  if  subjected  to  a  water-bath  during  the  early  stages 
of  setting.  Likewise  a  cement  which  is  accompanied  by  a  certain 
movement  when  mixed  thin  may  give  a  different  one  when  mixed  to  a 
thicker  consistence. 

In  much  the  same  manner  a  cement  which  is  mixed  rapidly  and  for 
a  long  time  may  have  a  different  movement  if  hastily  mixed  for  a  short 
time.  In  the  one  instance  there  is  more  nearly  a  combining  weight 
of  powder  for  each  combining  weight  of  liquid,  while  with  the  other 
there  are  likely  to  be  many  more  combining  weights  of  powder  than 
of  liquid  or  many  granules  of  zinc  oxid  not  acted  upon  by  the  liquid 
on  account  of  insufficient  mixing.  Like  the  question  of  solubility, 
no  standards  have  been  established,  and  it  is  therefore  not  possible 
to  give  the  same  amount  of  data  concerning  this  phenomenon  as  is 
possible  with  amalgams. 

Strength. — ^What  has  been  said  regarding  the  variables  connected 
with  solubility  and  volume  change  in  a  general  way  applies  to  the 
strength  of  cements.  Almost  any  strength  may  be  obtained  from  150 
kg.  to  700  kg.  on  a  cylinder  1  cm.  in  diameter,  depending  upon  the 
kind  of  cement,  the  manner  of  mixing,  humidity  of  the  atmosphere 
in  which  it  sets,  etc. 

Some  cements  show  a  retrogression  in  strength  if  tested  dry  and 
after  having  been  subjected  to  saliva  or  water.  This  is  an  indication 
of  the  destructive  influence  of  the  saliva  and  water,  and  is  also  some- 
what of  an  index  of  the  solubility  of  the  cement. 

Hydraulicity. — Hydraulicity  is  a  term  comparatively  recently  applied 
to  dental  cements  which  set  promptly  in  the  presence  of  consid- 
erable moisture  in  the  atmosphere  or  even  in  the  presence  of  water. 
This  property  seems  to  accompany  the  cements  so  manufactured 
that  they  are  rapid  setting.  With  a  given  manufacturer's  cements 
it  will  be  found  that  the  rate  of  setting  is  controlled  by  the  dentist 
by  furnishing  different  grades  of  liquid.  These  are  often  marked 
"A,"  "B,"  "C,"  etc.  Sometimes  they  sire  marked  rapid  setting, 
medium  setting,  slow  setting,  etc.  It  will  generally  be  observed  that 
hydraulicity  disappears  somewhat  as  the  slower  setting  liquids  are 
used.  Since  the  rate  of  setting  is  controlled  to  a  large  extent  by  the 
amount  of  water  in  the  liquid  and  powder,  hydraulicity  may  be  changed 
by  exposure  of  either  liquid  or  powder  to  the  atmosphere.  As  a  general 
rule  the  silicate  cements  are  more  sensitive  to  alteration  than  the  zinc 
oxyphosphates.  What  generally  happens  when  cement  liquids  are 
exposed  is  loss  of  water,  and  as  a  result  the  cement  is  slower  setting  and 


400  PROPERTIES  OF  FILLING  MATERIALS 

less  hydraulic;  and  when  cement  powders  are  exposed  to  a  humid 
atmosphere  the  result  is  absorption  of  water  and  more  rapid  setting. 
It  should  be  remembered,  however,  that  the  formula  of  the  cement 
and  the  method  of  manufacture  are  factors  which  influence  these 
phenomena. 

Adhesion. — ^The  property  of  adhesion  is  one  that  is  usually  developed 
to  the  highest  degree  in  the  zinc  oxyphosphates.  Like  most  other 
properties  of  cements  it  is  influenced  by  mixing,  humidity,  consistency, 
etc.  Adhesion  gradually  appears  as  the  powder  portion  is  added  to  the 
liquid  portion  up  to  a  certain  consistency  for  each  cement  and  gradually 
disappears  as  a  putty-like  consistency  is  reached.  For  the  retention 
of  inlays,  bands  or  crowns  which  are  likely  to  be  subjected  to  con- 
siderable stress  it  is  desirable  to  have  adhesion  developed  to  the  highest 
degree.  It  should  be  the  aim  of  the  dentist,  therefore,  to  learn  the 
consistency  which  results  in  the  greatest  adhesion. 

Mixing  Oxyphosphate  Cement. — It  is  usually  advisable  to  have 
everything  in  readiness  before  the  powder  and  liquid  are  exposed  to 
the  air,  for,  as  has  been  pointed  out,  both  are  likely  to  have  marked  - 
changes  produced  in  them  by  alteration  of  the  water  content.  When 
the  powder  and  liquid  are  placed  upon  the  glass  slab  they  should  be 
mixed  at  once  and  inserted.  The  amount  of  cement  to  be  mixed  may 
be  determined  by  placing  upon  one  end  of  the  slab,  one,  two,  three 
or  more  drops  of  the  liquid.  On  the  other  end  may  be  placed  a  sufficient 
amount  of  powder  to  make  either  a  thin  mix  or  a  thick  one  as  the  case 
demands.  The  powder  should  be  divided  into  from  six  to  eight  portions 
before  beginning  the  mix.  One  of  the  portions  should  be  drawn  into 
the  full  amount  of  liquid  and  thoroughly  spatulated,  after  which 
another  should  be  drawn  in.  This  should  be  repeated  until  the  con- 
sistency required  for  a  given  operation  is  obtained.  For  the  cemen- 
tation of  an  inlay  a  consistency  that  will  permit  the  cement  to  drop 
slowly  from  the  spatula  is  most  suitable.  For  a  cement  filling  a  con- 
sistency that  is  thick  enough  to  enable  the  operator  to  handle  it  withv 
but  little  adherence  to  instruments  is  usually  best.  If  a  large  mass  of 
powder  be  suddently  incorporated  with  the  liquid  and  stirred  the  result 
will  be  the  generation  of  excessive  heat,  and  as  a  result  of  the  heat  the 
cement  will  set  very  rapidly.  If,  on  the  other  hand,  the  powder  be 
added  slowly  and  each  portion  thoroughly  spatulated  the  heat  gener- 
ated will  be  conducted  away  by  the  slab.  There  is  a  marked  difference 
in  the  properties  of  a  cement  which  has  a  given  consistency  reached  by 
adding  rapidly  a  little  powder  thus  causing  the  cement  to  set  rapidly, 
and  one  which  has  a  similar  consistency  reached  by  adding  much  more 
powder  more  slowly.  The  latter  with  more  powder  will  possess  many 
more  desirable  properties  than  the  former.  The  aim  of  the  dentist  should 


GUTTA-PERCHA  401 

be  to  incorporate  with  the  Hqiiid  all  the  powder  possible  and  maintain 
the  consistency  which  the  operation  demands.  This  is  overlooked  by 
many  dentists  and  their  failures  from  the  use  of  cements  may  in  many 
cases  be  traced  to  the  use  of  a  cement  which  had  a  consistency  reached 
by  rapid  setting  instead  of  one  which  had  a  consistency  reached 
by  the  incorporation  of  more  powder.  A  mass  of  cement  which  has 
reached  a  certain  consistency  by  the  addition  of  plenty  of  powder  will 
set  very  quickly  when  it  comes  in  contact  with  a  warm  tooth,  but  when 
set  is  a  much  better  cement  from  every  other  standpoint. 

Cements  should  be  mixed  upon  a  large  glass  slab  that  will  remain 
cool  during  the  mix,  and  should  be  spatulated  with  a  large  spatula 
that  will  hold  a  large  amount  of  the  cement  mass  under  the  spatula. 
Otherwise  the  spatulation  is  little  more  than  a  stirring  process  which 
does  not  combine  the  powder  and  liquid  as  well  as  thorough  spatulation. 
The  temperature  of  the  glass  slab  should  never  be  above  that  of  normal 
room  temperature,  and  usually  it  is  much  better  to  cool  the  slab  to 
about  16°  C.  The  mass  should  be  spread  well  over  the  slab  so  that  the 
temperature  will  not  rise  much  above  that  of  the  slab.  There  is  no 
occasion  to  hurry,  for  from  one  and  one-half  to  two  and  one-half 
minutes  may  be  devoted  to  spatulation  and  incorporation  of  the  powder 
and  liquid.  German  silver  or  platinum  or  gold  spatulas  are  preferable 
for  mixing  the  oxyphosphates  and  agate  spatulas  or  some  other  spatulas 
which  are  highly  non-corrosive  and  non-abrasive  should  be  used  for 
the  silicate  cements. 

The  technic  for  mixing  the  silicate  cements  varies  somewhat  with 
the  different  manufacturers'  products,  making  it  inadvisable  to  outline 
a  technic  for  mixing  them.  It  is  much  more  likely  to  yield  good  results 
if  the  user  of  these  products  follows  carefully  the  instructions  of  each 
manufacturer  as  they  are  issued  from  time  to  time  as  these  cements 
are  developed. 

GUTTA-PERCHA. 

The  gutta-percha  of  commerce  is  the  concrete  juice  of  the  Ison- 
andra  gutta,  an  evergreen  tree  of  the  order  of  Sapotacese,  found  chiefly 
in  the  Malay  peninsula  and  archipelago.  The  juice  is  secured  by 
tapping  the  cambium  layer  of  the  tree  and  catching  the  juice  as  it 
exudes.  The  juice  thus  obtained  undergoes  many  processes  for  puri- 
fication before  it  is  formed  into  sheets  as  seen  in  commerce  (see  works 
on  gutta-percha)  and  several  more  before  it  appears  in  the  market  for 
dental  purposes. 

"The  purified  gutta-percha  probably  consists  of  a  hydrocarbon 
(pure  gutta),  having  the  formula  CioHie;  albane,  C40H64O3;  and  a 
variable  compound  named  guttane.  Pure  gutta-percha  possesses  all 
26 


402  PROPERTIES  OF  FILLING  MATERIALS 

the  good  qualities  of  gutta-percha  in  a  much  enhanced  degree,  becoming 
soft  and  plastic  on  heating  and  hard  and  tenacious  on  cooling,  without 
being  in  the  least  brittle.  The  resins  seem  to  be  simply  accessory  com- 
ponents which  have  a  decidedly  detrimental  effect  when  they  pre- 
ponderate. Water,  wood  fibers,  bark,  sand,  etc.,  occur  as  mechanical 
impurities  of  gutta-percha."     (Obach.) 

It  will  be  seen  that  gutta-percha  resembles  rubber  in  composition, 
since  it  consists  chiefly  of  a  hydrocarbid,  in  which  the  two  elements, 
carbon  and  hydrogen,  are  present  in  similar  proportions.  Gutta- 
percha resembles  rubber  also  in  its  origin,  both  coming  from  the  milky 
juice  of  certain  trees,  although  some  claim  a  superior  quality  of  gutta 
is  obtained  by  processes  of  extraction  from  the  dried  leaves  and  buds. 
Apart  from  these  similarities  the  two  substances  are  not  so  very 
similar.  Rubber  is  a  very  elastic  body,  i.  e.,  it  is  capable  of  returning 
to  its  original  form  when  a  mechanical  force  causes  it  to  undergo  a 
change.  Gutta-percha,  on  the  other  hand,  has  a  tendency  to  preserve 
the  change  in  form  produced  on  it  by  the  action  of  similar  forces. 
Rubber  containing  no  sulphur  softens  under  heat,  as  does  gutta-percha,- 
but  preserves  its  elasticity  if  the  heat  be  kept  within  certain  limits; 
beyond  a  definite  degree  of  heat  its  physical  and  chemical  properties 
are  altered.  Gutta-percha,  on  the  contrary,  under  heat  which  does  not 
exceed  110°  C,  is  very  plastic  and  malleable  and  on  cooling  preserves 
the  appearance  and  shapes  which  have  been  given  to  it  while  in  the 
plastic  state.  Several  other  differences  between  the  two  exist,  such  as 
the  action  of  light,  moisture,  and  air,  the  action  of  sulphur  on  the  two, 
their  non-conducting  properties,  etc.,  though  the  principal  difference 
in  this  connection  is  their  elasticity. 

Because  gutta-percha  preserved  the  shape  given  to  it  exceedingly  well 
for  a  material  of  its  nature,  it  was  introduced  as  a  filling  material  into 
dental  practice,  according  to  Dr.  Kirk,  about  the  year  1847.  Since 
that  time  several  secret  preparations  have  been  introduced,  all  of  which 
have  probably  been  gutta-percha  to  which  other  substances  have 
been  added  for  the  purpose  of  changing  the  physical  properties  by 
improving  the  desirable  ones  and  masking  or  destroying  the  undesirable 
ones.  One  of  the  first  to  appear  was  by  Dr.  Hill,  which  received  his 
name.  Several  analyses  of  Hill's  stopping  have  been  given,  all  of 
which  are  probably  untrustworthy.  Dr.  Herman  Prinz,^  however, 
gives  the  formula  of  Hill's  stopping  as:  feldspar,  1  part;  quartz,  1 
part;  quicklime,  2  parts;  gutta-percha  base-plate,  a  sufficient  quantity 
to  make  a  stiff  mass. 

Dr.  Prinz  does  not  give  his  authority  for  this  formula,  although  it 

1  Dental  Formulary. 


GUTTA-PERCHA  403 

would  seem  that  if  both  feldspar  and  quartz  were  added  it  would  be  done 
empirically.  Dr.  Kirk  has  said:  "It  subserved  so  useful  a  purpose 
that  it  received  the  tribute  of  wide  imitation;  in  fact  the  white  gutta- 
percha preparations  of  the  present  day  had  their  foundation  in  this 
imitation."  Undoubtedly  the  present  gutta-perchas  and  their  modi- 
fications have  gradually  developed  from  this  preparation  in  the  same 
manner  that  other  filling  materials  have  become  very  complex  com- 
pounds as  a  result  of  years  of  study.  The  gutta-perchas  for  dental  use 
are  divided  into  three  classes  according  to  the  temperature  of  softening: 
"Low  heat,"  softening  below  200°  F.;  "medium  heat,"  becoming 
plastic  at  200°  to  212°  F.;  "high  heat,"  210°  to  220°  F.  The  three 
kinds  are  often  numbered  to  distinguish  them  from  each  other,  one 
manufacturer  assigning  No.  6^  to  the  low  heat,  No.  7|  to  the  medium 
heat  and  No.  8^  to  the  high  heat  gutta-percha.  According  to  Kirk 
the  low  heat  gutta-percha  contains  about  1  part  by  weight  of  gutta- 
percha to  4  of  zinc  oxid;  in  medium  heat  the  ratio  is  1  to  6  or  7;  and 
in  the  high  heat  specimens  the  gutta-percha  is  almost  saturated  with 
zinc  oxid. 

In  some  of  the  products  materials  other  than  zinc  oxid  are  used  to 
mix  with  the  gutta-percha.  The  proportions,  however,  remain  about 
the  same.  Calcium  carbonate,  some  of  the  sulphates,  silica  and  other 
oxids  are  among  the  substances  claimed  to  be  substituted  for  the  zinc 
oxid. 

Physical  Properties. — Gutta-percha  in  the  pure  state  is  almost 
colorless,  the  small  amount  of  coloration  varying  from  rose  to  grayish 
white.  It  is  inodorous  and  insipid.  It  is  naturally  cellular  in  structure 
but  if  drawn  out  its  texture  becomes  fibrous  and  more  resistant  length- 
wise and  less  transversely.  It  will  not  break  until  a  load  of  about 
25  kg.  per  square  millimeter  has  been  applied  to  it.  It  is  but  slightly 
elastic.  It  is  a  very  good  non-conductor  of  both  heat  and  electricity. 
It  contracts  in  hardening,  i.  e.,  cooling.  Its  density  varies  from  slightly 
under  that  of  water  to  slightly  over  it,  depending  upon  the  compression 
given  to  it  in  forming  it  into  sheets.  To  the  vital  tissues  it  is  very 
bland.  Gutta-percha  which  has  been  in  the  mouth  for  some  time  often 
becomes  harder,  and  its  surface  porosity  is  increased.  Kirk  states  in 
regard  to  these  changes:  "The  increased  hardness  is  observed  in 
such  situations  as  those  in  which  putrefactive  decomposition  occurs; 
that  is,  in  places  where  there  is  an  evolution  of  hydrogen  sulphid;  the 
gutta-percha  apparently  undergoes  a  species  of  vulcanization.  It 
becomes  somewhat  porous  in  those  situations  where  the  formation  of 
a  solvent  is  active  (lactic  acid),  which  abstracts  the  soluble  zinc  oxid 
from  the  mass.  The  pink  variety  containing  the  insoluble  mercury 
sulphid  does  not  become  porous  but  wears  with  a  comparatively 


404  PROPERTIES  OF  FILLING  MATERIALS 

smooth  surface  when  subjected  to  attrition."  This  would  seem  to 
explain  some  of  the  changes  very  satisfactorily,  but  there  are  some 
where  other  explanations  would  seem  to  apply.  For  example,  gutta- 
percha which  has  been  exposed  to  air  and  light  becomes  friable  like 
resin  and  its  solubility  in  certain  reagents  is  increased.  If,  however, 
the  gutta-percha  be  submerged  in  water  no  perceptible  change  is 
produced.  Oxygen  aided  by  light  is  supposed  to  be  the  factor  of  prime 
importance  in  this  change,  and  as  a  result  the  process  is  generally 
spoken  of  as  oxidation,  although  some  refer  to  it  as  resinification,  since 
the  extent  of  the  change  depends  largely  upon  the  resin  present  in  the 
gutta-percha.  Thus  it  would  seem  that  oxygen  produces  a  condition 
in  gutta-percha  quite  analogous  to  the  one  observed  by  Kirk,  which 
he  has  attributed  to  the  action  of  sulphids.  In  both  cases,  however, 
whether  the  gutta-percha  be  in  the  mouth  or  out  of  it,  the  change  is 
apparently  what  he  has  called  "a  species  of  vulcanization."  What 
Kirk  states  regarding  the  porosity  of  the  surface  is  probably  true.  It 
would  seem,  however,  since  the  solubility  of  gutta-percha  in  alkalies 
increases  with  oxidation,  that  there  was  a  chance  for  the  surface  to 
become  porous  in  the  absence  of  lactic  acid.  Gutta-percha  in  the 
normal  condition  is  insoluble  in  dilute  acids  and  concentrated  alkalin 
solutions.  It  is  soluble  in  carbon  bisulphid,  chloroform,  coal-tar  oils, 
benzol,boiling  ether  and  oil  of  turpentine. 

Indications  for  Employment. — Gutta-percha  in  its  white  and  pink 
forms,  and  in  the  three  classes,  low,  medium  and  high  heat,  is  used 
as  a  temporary  filling  material  for  both  the  temporary  and  permanent 
teeth.  Its  non-conductivity  makes  it  a  good  material  to  place  near  the 
pulp.  Conditions  are  met  in  which  the  use  of  gold,  amalgam,  zinc 
oxyphosphates,  and  silicate  cements  alone  is  contra-indicated  because 
of  the  close  proximity  to  the  pulp.  In  such  cases  a  thin  layer  of  gutta- 
percha may  be  placed  over  the  pulp,  after  which  the  permanent  filling 
materials  may  be  inserted  without  serious  injury  to  the  pulp  from 
thermal  changes.  It  has  been  quite  a  common  practice  to  fill  deep 
undercuts  with  gutta-percha  and  cover  it  with  amalgam  or  cement,  or 
cement  and  gold,  but  recent  requirements  for  better  cavity  formation 
seem  to  have  created  a  demand  for  a  harder  material,  and  as  a  result 
the  zinc  oxyphosphates  have  been  more  widely  used. 

Gutta-percha  is  generally  used  to  fill  the  pulp  chambers  of  devitalized 
teeth,  but  even  here  it  is,  as  a  rule,  conceded  better  practice  to  confine  it 
to  the  root  portion  of  the  pulp  cavity  and  to  fill  any  remaining  portions 
which  require  a  similar  plastic  material  with  one  of  the  best  zinc  oxy- 
phosphates. It  has  been  used  extensively  for  cervical  cavities  in  molars 
and  bicuspids  which  do  not  extend  to  the  masticating  surfaces,  but  the 
demand  for  better  oral  hygiene  is  such  that  this  practice  has  become 


GUTTA-PERCHA  405 

less  common  except  for  relatively  temporary  operations.  It  has  been 
used  for  all  classes  of  cavities  in  the  temporary  teeth,  and  often  seems 
to  be  practically  the  only  available  material  which  will  meet  the  requne- 
ments  of  these  cases.  There  is  a  tendency,  however,  to  use  less  gutta- 
percha in  the  temporary  teeth  because  of  the  demands  of  orthodontists 
for  the  retention  of  normal  contact  when  restoring  proximate  portions 
of  these  teeth.  There  is  likewise  a  tendency  to  use  it  less  in  other 
locations  in  the  deciduous  teeth  for  the  reasons  previously  given  in 
regard  to  better  oral  hygiene. 

To  the  casual  observer  it  might  seem  from  this  that  there  was  little 
use  to  which  gutta-percha  might  be  put.  Such,  however,  is  not  the 
case.  Instead  there  are  a  great  many  places  where  gutta-percha  seems 
to  satisfy  more  of  the  requirements  than  any  other  material.  There  are 
places,  however,  where  its  insertion  represents  almost  anything  but 
cleanliness.  Many  have  a  misconception  regarding  the  impermeability 
of  gutta-percha,  and  as  a  result  are  reluctant  to  substitute  other 
materials  when  it  can  as  well  be  done. 

Dr.  Black^  says:  "The  trial  that  has  been  made  of  gutta-percha 
for  the  exclusion  of  moisture  for  long  periods  of  time  from  ocean  cables 
has  shown  its  absolute  impermeability."  That  gutta-percha,  used  as 
a  cover  for  ocean  cables,  is  almost  impervious,  is  conceded,  but  it  is 
to  be  regretted  that  this  statement  was  not  qualified  somewhat, 
because  as  it  stands  the  average  person  would  take  it  that  gutta-percha 
was  likewise  impervious  in  the  mouth. 

Attention  has  already  been  called  to  the  fact  that  gutta-percha  did 
not  combine  perceptibly  with  the  oxygen  of  water,  but  that  it  did  with 
the  oxygen  of  the  air  in  the  presence  of  light.  Under  the  latter  con- 
ditions gutta-percha  undergoes  rapid  decay  and  gives  off  an  acrid 
odor.  Kirk  has  called  attention  to  the  action  of  sulphids  upon  gutta- 
percha. Thus  while  gutta-percha  is  impervious  when  inserted  it  under- 
goes decay  from  at  least  two  causes.  Of  course,  it  will  remain  in  the 
mouth  for  a  considerable  length  of  time  before  the  decay  becomes  very 
perceptible,  but  fillings  of  long  standing  will  show  considerable  change. 

Gutta-percha  is  still  a  very  useful  material,  but  it  should  not  be 
allowed  to  remain  exposed  to  the  oral  fluids  for  any  great  length  of 
time.  It  may  be  used  to  set  almost  all  kinds  of  crowns  on  roots  which 
have  been  prepared  for  their  reception,  but  should  be  allowed  to  remain 
for  a  comparatively  short  time  only.  Often  an  operation  may  be  nearly 
complete,  but  the  operator  may  wish  to  do  something  more  before  a 
crown  is  placed  permanently.  In  such  cases  a  little  gutta-percha  which 
has  been  made  plastic  by  heat  may  serve  to  retain  a  crown. 

1  Operative  Dentistry,  vol.  ii. 


406  PROPERTIES  OF  FILLING  MATERIALS 

The  same  is  true  regarding  its  use  for  fillings.     In  an  extensive 
inlay  practice  gutta-percha  is  almost  indispensable  as  a  temporary 
stopping  from  the  time  the  cavity  is  prepared  until  the  inlay  is  ready 
to  be  set.    It  is  usually  best  not  to  allow  much  time  to  elapse  between 
the  preparation  of  the  cavity  and  the  setting  of  the  inlay,  but  in  an 
extensive  practice  occasions  continually  arise  in  which  this  is  necessary. 
Gutta-percha  may  be  used  for  sealing  in  treatments  in  the  teeth  when 
the  cavity  is  sufficiently  large  to  permit  of  its  adaptation  without  com- 
pression of  the  pulp,  or  where  the  stress  of  mastication  will  not  dislodge 
it.     Dr.  Black^  states  that  "It  should  be  the  only  material  used  for 
sealing  in  dressing  and  for  the  temporary  stoppings  in  connection  with 
treatments."    As  he  says,  gutta-percha  is  a  trying  material  to  handle 
until  the  technic  of  its  manipulation  has  been  mastered,  but  it  is  diffi- 
cult to  understand  why  he  should  declare  that  it  is  the  only  material 
which  should  be  used  for  sealing  in  dressings,  etc.,  when  it  is  generally 
conceded  that  the  zinc  oxyphosphates  fulfil  many  requirements  better 
than  gutta-percha.    For  example,  suppose  an  accidental  exposure  is 
made  in  the  preparation  of  a  cavity  of  a  young  patient  in  whom  the. 
pulp  is  near  the  surface,  or  suppose  that  the  exposure  has  been  made  by 
caries  and  the  pulp  is  in  a  highly  inflamed  condition.    In  either  case 
the  medicinal  agent  would  probably  be  mixed  with  one  of  the  nicely 
prepared  oxids  as  a  carrying  agent  and  placed  gently  over  the  exposure. 
As  a  sealing  for  the  cavity,  shallow  as  most  are,  nothing  would  seem 
to  meet  the  requirements  as  well  as  one  of  the  adhesive  zinc  oxy- 
phosphates,  which   could  be   applied  without  perceptible  pressure. 
There  are  many  cavities  which  present  a  different  problem.    They  may 
be  deep  and  easy  of  access.     In  such  cases  gutta-percha  would  be 
preferable  to  any  other  material. 

One  of  the  first  considerations  is  that  the  surfaces  to  which  gutta- 
percha is  applied  should  be  dry  and  free  from  greasy  materials.  This 
may  be  accomplished  by  the  adjustment  of  the  rubber  dam  or  by  the 
use  of  rolls  and  the  aid  of  an  assistant,  according  to  the  case  treated. 
If  the  gutta-percha  is  to  be  inserted  into  a  cavity  the  walls  should  be 
parallel  or  even  have  slight  retaining  points,  although  in  most  cases 
the  cavity  formation  may  be  varied  somewhat  from  that  for  gold  or 
amalgam. 

When  the  cavity  has  been  prepared  for  the  filling  it  is  often  found 
advantageous  to  moisten  the  walls  with  eucalyptol  or  cajuput  oil. 
This  will  soften  the  gutta-percha  somewhat  and  add  to  its  adhesive- 
ness. The  gutta-percha  should  then  be  made  plastic  by  passing  it  over 
the  flame  or  by  placing  it  upon  one  of  the  specially  designed  heaters. 
It  is  often  convenient  to  use  the  different  varieties  of  gold  annealers 

1  Operative  Dentistry,  vol.  ii. 


GUTTA-PERCHA 


407 


r^ 


Fig.  355. — Flagg's  gutta-percha  softener  and  tool  heater. 


408  PROPERTIES  OF  FILLING  MATERIALS 

for  this  purpose.  The  heater  most  commonly  used  is  made  of  steatite, 
and  is  shown  in  Fig.  354.  The  heat-retaining  properties  of  soapstone, 
together  with  its  desirable  surface,  make  it  as  good  a  heater  as  any 


Fig.  356. — Trimmer  for  gutta-percha  heated  by  electricity. 

that  have  been  designed.  After  the  gutta-percha  has  been  softened 
it  may  be  rolled  into  a  single  piece  of  a  shape  convenient  for  insertion, 
and  packed  in  place  with  cool  instruments.  It  may  also  be  inserted 
gradually  by  adding  piece  after  piece  to  the  walls  of  the  cavity  and  the 


GUTTA-PERCHA 


409 


already  inserted  gutta-percha.  This  method  is  usually  better  if  there 
is  not  easy  access  or  if  there  is  danger  of  compressing  the  pulp  or  forcing 
medicinal  agents  through  the  apical  foramen  in  devitalized  teeth. 
After  the  cavity  is  filled  it  should  be  trimmed  to  shape  with  the  ordinary 
plastic  instruments  by  warming  them  to  a  point  where  they  will  cut 
through  the  gutta-percha  without  tending  to  draw  it  from  the  cavity. 
The  instruments  should  be  heated  gently  in  the  flame  or  in  one  of  the 
heaters,  as  shown  in  Fig.  355.  Several  instruments  which  are  heated 
by  the  electric  current  have  been  designed  for  trimming  gutta-percha 
(Fig.  356).  They  are  very  useful  for  some  operations,  but,  as  a  general 
rule,  a  little  more  clumsy  than  the  regular  plastic  instruments. 


Fig.  357 


For  finishing  some  gutta-percha  fillings  where  it  is  not  necessary  to 
direct  the  blast  of  hot  air  against  the  soft  tissues  the  hot  air  syringe 
is  useful.  It  may  be  used  in  heating  crowns  which  have  been  set 
temporarily  with  gutta-percha.  With  this  instrument  a  blast  of  hot 
air  may  be  directed  against  a  porcelain  crown,  having  a  metal  post, 
until  it  can  be  removed  easily.  When  the  hot-air  syringe  is  used  to 
soften  the  gutta-percha  only  very  sharp  instruments  should  be  used 
to  trim  off  the  excess,  or  the  mass  will  be  moved  in  the  cavity.  In 
general,  gutta-percha  should  not  be  warmed  after  being  inserted  into 
the  cavity,  but  should  be  chilled  and  trimmed  with  warm,  sharp  instru- 
ments. Gutta-percha  may  be  trimmed  into  shape  with  the  ordinary 
plastic  instruments  by  warming  them.  It  is  better,  however,  to  use 
more  of  the  sharp-edged  instruments,  such  as  carvers  and  excavators. 
Heat  may  also  be  conveyed  to  large  masses  of  gutta-percha,  especially 
in  removing  crowns  set  with  this  material,  by  heating  a  larger  burnisher 
and  placing  it  upon  the  mass  of  gutta-percha.  It  is  still  better  to  place 
a  good-sized  piece  of  copper  upon  an  instrument  handle  (Fig.  357). 

For  the  use  of  gutta-percha  as  a  root  canal  filling  see  Chapter  IX. 


410  PROPERTIES  OP  PlLLlNO  MAT§RIALS 

Gutta-percha  with  Other  Materials.— Temporary  Stopping. — ^This 
material  differs  from  ordinary  gutta-percha  chiefly  in  its  working 
qualities.  It  is  prepared  from  both  white  and  pink  gutta-percha  by 
the  addition  of  some  of  the  gums  or  waxes,  together  with  other  materials 
such  as  certain  sulphates,  carbonates  or  oxids. 

It  is  also  made  without  the  gums  or  waxes.  It  may  be  prepared  so 
that  it  exhibits  considerable  adhesiveness  by  the  addition  of  Burgundy 
pitch.  These  preparations  are  designed  for  a  variety  of  purposes; 
their  principal  use  is  the  stopping  of  excavated  cavities  for  a  short 
time. 

As  the  name  implies  they  are  intended  for  work  more  temporary  in 
nature  than  that  which  would  require  gutta-percha.  As  a  result  of 
their  use  for  the  most  temporary  operations  many  of  the  qualities  of 
other  plastics  have  been  given  to  this  material  by  the  addition  of  some 
of  the  above-named  materials.  Many  of  these  preparations  remain 
quite  hard  in  the  mouth,  although  some  are  less  resistant  than  gutta- 
percha, and  more  plastic  in  every  way.  The  most  conspicuous  differ- 
ences between  them  and  gutta-percha  are  that  they  are  generally 
softened  with  lower  heat  and  have  little  or  none  of  the  toughness  and 
stringiness  so  prominent  in  gutta-percha.  Their  manipulation  is 
similar  to  that  of  gutta-percha. 

Gutta-percha  and  Gum  Shellac. — Gutta-percha  may  be  mixed  with 
gum  shellac  to  make  a  stiff  and  yet  tough  material,  for  use  largely  as 
a  base-plate.  It  may  be  used,  however,  for  a  variety  of  purposes  where 
other  forms  of  gutta-percha  would  scarcely  be  rigid  enough. 

Gutta-percha  with  Medicinal  Agents.^ — Such  substances  as  oxid  of 
copper,  finely  divided  tin,  silver  nitrate,  eucalyptol,  creosote,  etc.,  are 
often  incorporated  with  gutta-percha.  It  is  claimed  by  the  makers 
of  some  of  the  gutta-percha  points  supplied  for  filling  root  canals  that 
the  process  of  refining  the  crude  gutta-percha  removes  a  natural  oil 
which  should  be  supplied  before  the  points  are  suitable  for  use.  The 
addition  of  some  of  the  oils  in  such  cases  not  only  supplies  what  it  is 
asserted  to  have  been  removed,  but  for  a  time  makes  the  points  more 
or  less  antiseptic. 

The  other  substances  mentioned  are  less  frequently  added  to  gutta- 
percha. The  salts  of  copper  and  finely  divided  tin  may  be  advan- 
tageously incorporated  when  it  seems  imperative  to  leave  gutta- 
percha in  the  mouth  exposed  to  the  saliva  for  some  time.  The  use  of 
gutta-percha  with  either  of  these  materials  is  hmited  to  remote  parts 
of  the  mouth  on  account  of  their  color.  The  manipulation  of  these 
mixtures  is  similar  to  that  of  gutta-percha  alone.  When  these  two 
materials,  or  other  similar  substances,  are  combined  with  gutta- 
percha, the  resulting  product  is  not  unlike  it,  but  some  of  the  properties 
of  the  combined  substance  are  added. 


CHAPTER  VIII. 

THERAPEUTIC  PROCEDURES  IN  THE  TREATMENT  OF 
INFECTED  ROOT  CANALS. 

By  HERMANN  PRINZ,  A.M.,  M.D.,  D.D.S. 

A  MOST  serious  question  that  confronts  the  dental  profession  today — 
and  for  that  matter  has  confronted  it  in  the  past — is  that  which  is 
involved  in  establishing  absolute  sterility  of  an  infected  root  canal. 
The  disposal  of  this  problem  in  a  truly  scientific  manner  necessitates 
the  determination  of  the  established  sterility  by  bacteriologic  tests 
in  each  individual  case.  While  the  author  realizes  that  the  carrying 
out  of  such  procedures  in  the  average  dental  qpice  of  today  will  meet 
with  numerous  difficulties,  due  to  the  fact  that  the  older  members  of 
our  profession  have  not  had  sufficient  training  in  these  directions, 
nevertheless  there  exists  no  good  reason  why  it  should  not  be  done  by 
the  recent  graduate  who  has  received  adequate  instructions  in  labora- 
tory technic.  The  time  is  not  far  distant  when  the  public  will  demand 
a  laboratory  diagnosis  of  serious  root-canal  infections  for  the  same 
reason  that  a  bacteriologic  examination  of  a  diphtheritic  throat  is 
demanded  at  present.  Since  the  sequences  of  imperfect  root-canal 
sterilization  in  the  form  of  focal  infections  resulting  in  metastatic  dis- 
turbances of  distant  organs  are  of  common  occurrence,  it  must  follow 
that  our  present  methods  of  establishing  perfect  sterility  of  an  infected 
root  canal  are  inadequate. 

From  a  logical  deduction  based  upon  the  much  discussed  problem  of 
infected  root  canals,  it  is  evident  that  its  treatment  resolves  itself 
into  three  definite  procedures:  the  mechanical,  the  chemical  and  the 
therapeutic.  Mechanical  manipulations  are  intended  to  dispose  of  the 
debris  of  the  dead  pulp,  chemical  procedures  are  primarily  applied  for 
the  purpose  of  facilitating  the  removal  of  obstructions,  and  therapeutic 
applications  are  utilized  to  overcome  septic  conditions. 

Chemical  Procedures. — For  the  chemical  disintegration  "of  the  pulp 
detritus,  but  primarily  for  the  purpose  of  assisting  in  the  opening  of 
obliterated  root  canals,  two  specific  methods  are  in  vogue,  viz.,  the 
alkali  method,  as  introduced  by  Schreier  in  1892,  and  the  acid  method, 
as  advocated  by  the  late  Callahan  in  1893.  Schreier's  alkali  method 
intends  to  destroy  the  organic  substances  by  means  of  the  freshly 
formed  hydroxids  of  potassium  and  sodium  derived  from  an  alloy  of 

(411) 


412  TREATMENT  OF  INFECTED  ROOT  CANALS 

potassium  and  sodium  in  the  presence  of  water.  Thereby  the  remain- 
ing inorganic  debris  is  rendered  more  friable  and  offers  less  resistance 
to  the  advancing  broach  or  reamer.  Callahan's  sulphuric  acid  treat- 
ment produces  the  opposite  effect,  i.  e.,  it  destroys  the  inorganic  sub- 
stances by  dissolution  and  carbonizes  the  remaining  organic  material. 
Both  methods  have  their  advocates,  and  as  they  virtually  accomplish 
the  same  purpose,  it  is  difficult  to  recommend  one  method  as  being 
superior  to  the  other.  The  preference  in  selecting  one  specific  method 
is  largely  a  matter  of  personality.  However,  a  most  important  physical 
property  possessed  by  the  alloy  and  not  possessed  by  the  acid  should 
be  mentioned  which  places  the  alkali  treatment  somewhat  at  an  advan- 
tage over  the  acid  treatment.  This  property  manifests  itself  as  a 
pronounced  capillary  affinity  of  the  freshly  formed  hydroxids  for  mois- 
ture, and,  consequently,  the  caustic  alkali  solution  penetrates  into 
those  minute  apertures  of  the  root  canal  which  a  broach  cannot  reach 
and  in  which  the  acid  will  not  flow.  The  author  has  observed  that  the 
opening  of  completely  obliterated  canals  is  often  materially  facilitated 
by  alternating  the  alkali  and  acid  methods.  Both  methods  incidentally, 
destroy  the  offensive  odor  of  putrescence  which  is  always  very  pro- 
nounced in  a  closed  root  canal  and  less  so  in  an  open  canal.  However, 
it  should  be  clearly  understood  that  the  complete  absence  of  foul  odors 
is  by  no  means  an  indication  of  sterility. 

Dental  potassium  sodium  (kalium-natrium)  usually  consists  of  one 
part  of  metallic  potassium  and  two  parts  of  metallic  sodium  melted 
together  beneath  kerosene.  It  is  of  a  pasty  consistency  and  resembles 
mercury  in  appearance.  The  alloy  is  supplied  in  small  glass  tubes 
sealed  with  wax  or  paraffin  to  protect  it  from  moisture.  In  using  this 
alloy  a  barbed  tantalum  or  an  iridio-platinum  broach  is  thrust  through 
the  paraffin  stopper  or  directly  into  the  broken-off  upper  end  of  the 
tube.  Steel  broaches  are  not  to  be  recommended  for  this  work;  the 
alloy  disintegrates  the  metal,  and,  as  a  consequence,  the  broaches 
frequently  break  in  the  canal.  The  very  small  quantity  of  the  paste 
adhering  to  the  broach  is  worked  into  the  pulp  debris.  At  once  a 
chemical  decomposition  of  the  contents  of  the  root  canal  takes  place, 
manifesting  itself  by  heat  and  a  hissing  sound,  with  the  escape  of  gas. 
Potassium-sodium  alloy  in  the  presence  of  water  is  changed  at  once 
into  its  respective  hydroxids  with  the  liberation  of  hydrogen.  The 
hydroxids  dissolve  in  the  remaining  water  and  form  a  more  or  less 
concentrated  caustic  alkaline  solution.  The  putrescent  pulp  contains 
water,  fat,  fatty  acids,  gases  and  the  debris  of  decomposed  protein 
material.  The  rationale  of  the  action  of  the  potassium-sodium  alloy 
on  the  putrescent  pulp  debris  present  in  a  root  canal  may  be  summar- 
ized as  follows:    fat  and  fatty  acids  are  changed  to  soluble  soaps. 


CHEMICAL  PROCEDURES  413 

The  protein  substances  are  rendered  soluble  by  the  caustic  hydroxid 
solution  and  the  liberated  hydrogen  forces  the  undissolved  debris  to 
the  surface  of  the  canal.  The  calcareous  deposits  in  the  lumen  and 
upon  the  walls  of  the  canals  lose  their  crystalline  structure  and  become 
friable  and  thereby  offer  less  resistance  to  the  advancing  broach.  The 
offensive  odor  of  putrescence  is  almost  instantly  destroyed.  Copious 
washing  with  water  will  remove  the  saponified  contents  of  the  canal, 
and,  on  drying,  its  clean  ivory-white  walls  are  visible.  The  substitution 
of  the  hydroxids  of  potassium  and  sodium  for  the  metallic  alloy  is  not 
to  be  recommended;  their  application  is  difficult  and  their  physical 
nature  does  not  lend  itself  to  this  procedure  as  readily  as  the  alloy 
from  which  the  above  hydroxids  are  obtained  in  statu  nacendi  during 
their  application.  The  tube  containing  the  alloy  must  be  hermetically 
sealed  directly  after  using  to  prevent  the  decomposition  of  the  latter 
by  moisture  absorbed  from  the  air.  If  the  sealing  is  not  carried  out 
in  a  proper  manner  the  operator  will  find  that  the  contents  of  the  tube 
will  change  to  a  hard,  crystalline  mass,  namely,  the  hydroxids  of  the 
two  metals. 

The  sulphuric  acid  method  for  opening  obstruction  root  canals  has 
found  many  admirers  among  the  practitioners,  and  it  is  probably  more 
widely  employed  at  present  than  any  other  chemical  procedure. 
Other  acids,  such  as  hydrochloric,  nitric,  nitro -hydrochloric  and 
phenol-sulfonic  have  been  advocated  for  this  purpose  during  the  last 
twenty-five  years.  The  strength  of  these  various  acids  as  used  for 
this  specific  purpose  should  be  carefully  noted  as  it  varies  greatl3\ 
Sulphuric  acid  is  usually  employed  in  approximately  a  50  per  cent, 
solution,  hydrochloric  acid  in  a  10  per  cent,  solution,  nitro-hydrochloric 
acid  either  pure  or  in  a  50  per  cent,  solution,  while  phenol-sulfonic 
acid  is  used  in  its  pure  form  only.  The  therapeutic  absurdity  of  the 
last  compound  has  been  dealt  with  by  the  author  on  a  former  occasion, 
and  consequently  it  is  omitted  in  the  present  discussion. 

Nitro-hydrochloric  acid  (aqua  regia)  as  introduced  by  G.  W.  Weld 
in  1897  is  the  most  efficient  acid  for  the  above  purposes.  It  should 
be  preserved  in  glass-stoppered  bottles  and  kept  outside  of  the  operating 
room,  as  its  fumes  are  most  destructive  to  metallic  instruments.  A 
50  per  cent,  solution  of  this  acid  may  be  prepared  as  follows: 

Nitric  acid 1  dram     (  4  c.c.) 

Hydrochloric  acid 4  drams  (16  c.c.) 

Water 5  drams  (20  c.c.) 

It  may  be  applied  upon  a  steel  broach.  Concentrated  aqua  regia 
has  practically  very  little  eftect  on  steel,  as  the  broach  is  at  once 
covered  by  a  protective  oxid  by  the  action  of  the  evolved  nitrosyl 
chlorid,  which  checks  the  further  action  of  the  acid  upon  the  metal. 


414  TREATMENT  OF  INFECTED  ROOT  CANALS 

Whatever  acid  is  employed  it  should  be  neutralized  by  sodium 
dioxid,  as  recommended  by  Kirk  in  1893,  and  not  by  sodium  bicar- 
bonate, which  is  practically  of  very  little  value  for  this  specific  purpose. 
The  sodium  dioxid  is  carried  into  the  root-canal  by  means  of  a  broach 
previously  dipped  into  chloroform;  the  latter  liquid  merely  acts  as  an 
indifferent  conveyer  of  the  sodium  dioxid  to  the  root  canal,  which  if 
water  or  ordinary  alcohol  were  used  readily  decomposes.  The  chemical 
interchange  between  the  various  acids  may  be  portrayed  by  their 
respective  reactions  as  follows: 

H2SO4  +  Na202  =       NaaSOi  +  H2O2. 

or2HCL  +  Na202  =  2NaCl  +  H2O2. 

or  2HNO3  +  Na202  =  2NaN03  +  H2O2  and 

2HCL  +  Na202  =  2NaCl  +  H2O2. 

The  freshly  formed  hydrogen  dioxid  of  the  last  reaction  combines 
with  the  available  hydrochloric  acid  and  forms  nascent  chlorin: 

H2O2     +     2HC1      =     2H2O  +    CI2. 

There  seems  to  be  quite  a  diversity  of  opinion  concerning  the  self-- 
limiting  action  of  these  acids  upon  tooth  structure.  Fifty  per  cent, 
sulphuric  acid  solution  is  self-limiting;  a  tooth  placed  in  this  acid  will 
be  coated  within  a  day  or  so  on  every  accessible  surface  with  freshly 
precipitated  insoluble  calcium  sulphate,  and  consequently  no  further 
action  occurs.  A  tooth  placed  in  10  per  cent,  hydrochloric  acid,  in 
pure  or  in  50  per  cent,  nitro-hydrochloric  acid,  will  be  completely  dis- 
solved in  two  or  three  days;  these  acids  form  soluble  calcium  salts. 
The  greatest  solvent  power  is  exhibited  by  50  per  cent,  nitro-hydto- 
chloric  acid. 

From  a  clinical  point  of  view  it  is  readily  understood  that  the  small 
quantities  of  either  acid  pumped  into  a  root  canal  when  used  with 
caution  will  do  no  harm,  especially  when  neutralized  by  sodium 
dioxid.  It  is  to  be  understood,  however,  that  no  acid  should  be  forced 
through  the  foramen. 

Therapeutic  Procedures. — Soon  after  the  inauguration  of  the  anti- 
septic era  in  surgery  (in  1868  by  Lister),  dentistry  adopted  his  methods 
for  the  treatment  of  root  canals  in  an  empiric  way  by  using  phenol  as 
advocated  by  Witzel  in  1873.  Since  then  innumerable  other  drugs 
and  drug  compounds  have  been  recommended  at  various  times  for 
this  purpose,  among  which  may  be  mentioned:  creosote,  phenol, 
chlorophenol,  lysol,  cresol,  creolin,  beta-naphthol,  salicylic  acid,  hydro- 
gen dioxid,  zinc  chlorid,  mercury  bichlorid,  silver  nitrate,  iodin  solu- 
tions, iodoform,  the  essential  oils,  thymol,  eugenol,  eucalyptol.  Black's 
1-2-3,  sodium  dioxid,  formaldehyd,  electro-sterilization  (ionization), 
dichloramin-T,  and  many  others.     From  a  clinical  point  of  view  the 


THERAPEUTIC  PROCEDURES  415 

cresol-formalin  mixture,  as  introduced  by  Gysi  in  1899  and  widely  popu- 
larized by  Buckley  in  1904,  has  received  greater  approval  than  any 
other  medicinal  compound  recommended  for  such  purposes.  The  true 
criterion  of  the  efficiency  of  an  antiseptic  is  its  bacteriologic  test 
upon  clinical  cases.  The  high  standard  of  the  germicidal  activity  of 
formalin  has  been  frequently  established  by  rigorous  experiments. 
Clinical  data  collected  in  the  early  days  of  the  use  of  the  above  mixture 
pointed  to  most  favorable  results.  In  due  time,  however,  it  was 
observed  that  while  "clearing  up"  of  an  infected  root  canal,  as  far  as 
the  ordinary  diagnostic  evidence  is  concerned,  as  applied  in  the 
average  dental  office,  i.  e.,  absence  of  foul  odor,  occurred  much  more 
rapidly  by  the  use  of  this  mixture  than  by  employing  any  of  the 
numerous  other  drugs  usually  advocated  for  this  purpose,  nevertheless 
secondary  manifestations  about  the  periapical  tissues  were  of  frequent 
occurrence.  These  disturbances  are  an  indication  that  the  supposed 
sterility  of  the  canal  was  not  obtained  at  the  time  of  its  treatment  with 
the  cresol-formalin  mixture  or  that  this  compound  produces  a  predis- 
position of  the  periapical  tissues  to  future  infections.  To  be  sure, 
dental  literature  is  pregnant  with  statements  such  as  this  (referring 
to  the  cresol-formalin  mixture) :  "  This  dressing  should  remain  for  at 
least  three  days,  by  which  time  the  remedy  will  have  sterilized  the 
entire  tubular  structure  of  the  dentin,  thus  establishing  asepsis." 
As  no  bacteriologic  proof  is  furnished  to  substantiate  the  claim,  this 
empirical  statement  does  not  carry  any  scientific  weight,  and  it  is  out 
of  harmony  with  existing  facts.  Asepsis  of  an  infected  root  canal 
can  be  temporarily  established  by  applying  mechanical  and  chemical 
measures,  but  complete  sterilization  of  "the  entire  tubular  structure 
of  the  dentin"  in  a  tooth  in  situ  is  impossible  with  the  methods  at 
present  in  vogue. 

In  regard  to  the  application  of  a  powerful  antiseptic  drug  for  the 
treatment  of  infected  root  canals,  one  should  be  always  mindful  of  the 
following  facts : 

1 .  The  agent  must  be  able  to  develop  the  highest  degree  of  antiseptic 
power  without  doing  harm  to  the  periapical  tissue. 

2.  It  must  maintain  its  activity  for  at  least  twenty-four  hours  when 
sealed  into  the  root  canal. 

3.  It  must  not  cause  pain. 

4.  It  must  not  discolor  the  tooth  structure. . 

Of  all  the  above  enumerated  drugs  only  a  very  few  answer  these 
requirements.  Without  entering  into  a  lengthy  discussion  of  the  merits 
or  demerits  of  these  drugs,  it  may  be  stated  that,  in  general,  the 
aromatic  series,  i.  e.,  phenol,  and  its  isomers,  are  caustic  when  applied 
in  concentrated  solution.     The  metallic  salts  are  strong  precipitants 


416  TREATMENT  OF  INFECTED  ROOT  CANALS 

of  albumin;  incidentally,  some  of  these  salts,  i.  e.,  mercury,  bichlorid 
and  silver  nitrate,  permanently  discolor  the  tooth  structure.  Iodo- 
form, on  account  of  its  most  disagreeable  odor  and  other  drawbacks, 
cannot  be  recommended  for  the  work  and  some  of  the  iodin  compounds 
produce  lasting  stains.  The  essential  oils  do  not  possess  sufficient 
antiseptic  power  as  compared  with  other  drugs.  Formaldehyd  in 
the  strength  in  which  it  is  usually  applied  for  root-canal  treatment  will 
always  kill  the  soft  tissues  when  brought  in  contact  therewith  either 
directly  or  in  vapor  form  in  the  same  manner,  as  the  ill-fated  desensitiz- 
ing paste  by  its  formalin  content  eventually  kills  the  pulp  through  any 
thickness  of  sound  dentin.  As  will  be  pointed  out  in  detail  later  under 
Reinfection  of  Root  Canals,  no  antiseptic  treatment  now  in  vogue  will 
permanently  sterilize  a  once  infected  root  canal. 

Of  all  known  antiseptics,  chlorin,  freshly  prepared,  and  in  the  pres- 
ence of  moisture  and  a  suitable  temperature,  possesses  the  highest 
germicidal  power.  In  suitable  concentration,  especially  in  an  oily 
solution,  it  is  harmless  to  the  periapical  tissues  and  maintains  its 
activity  for  about  twenty-four  hours  when  sealed  into  a  root  canal-. 
These  oily  chlorin  solutions  will  not  cause  pain  and  they  do  not  discolor, 
but  rather  "bleach"  tooth  structure. 

Regarding  the  concentration  of  the  solution  of  dichloramin-T  for 
the  purpose  of  treating  infected  root-canals,  we  have  found  that  a  5  per 
cent,  solution  of  the  salt  in  chlorinated  paraffin,  i.  e.,  chlorcosane, 
answers  our  purpose  quite  satisfactorily.  We  have  heard  an  opinion 
expressed  to  the  effect  that  a  5  per  cent,  solution  is  too  irritating  when 
used  in  root-canal  work.  We  cannot  subscribe  to  such  assertions; 
we  rather  believe  that  the  pain  resulting  from  its  application  was  due 
to  two  causes — a  spoiled  solution  and  a  faulty  technic. 

Solutions  of  dichloramin-T  preserve  their  activity  for  a  limited  time 
only;  they  usually  deteriorate  within  two  or  three  months,  and  therefore 
it  is  best  to  prepare  a  convenient  quantity  which  may  be  readily  used 
up  within  a  month  or  so.  To  prepare  an  ounce  of  the  solution,  25  grains 
of  dichloramin-T  are  placed  in  a  dark  amber-colored  glass-stoppered 
bottle,  which  must  be  absolutely  clean  and  free  from  moisture.  One 
ounce  of  chlorcosane  is  added,  the  whole  is  thoroughly  shaken  and  the 
bottle  is  placed  in  a  pan  containing  very  hat  water  or  upon  a  radiator 
or  other  source  of  indirect  heat.  Within  a  quarter  of  an  hour  complete 
solution  usually  results.  Direct  heat  in  making  the  solution  is  to  be 
avoided,  as  it  is  likely  to  injure  the  compound.  The  solution  is 
immediately  ready  for  use ;  filtering  is  not  necessary.  As  stated  above, 
only  dark  amber-colored  or  black  bottles  should  be  employed  as 
storage  vessels;  blue  glass  does  not  protect  the  solution  against  the 
actinic  effects  of  strong  light. 


THERAPEUTIC  PROCEDURES  417 

Solutions  of  dichloramin-T  must  be  carefully  protected  against  heat, 
light,  water,  alcohol  and  most  metals;  in  fact,  most  common  sub- 
stances have  a  strong  affinity  for  chlorin,  hence  the  ready  decomposition 
of  this  solution  when  brought  in  contact  therewith.  Whenever  the 
solution  becomes  turbid  and  forms  a  deposit  of  crystals  in  the  bottom 
of  the  bottle  or  develops  a  pronounced  odor  of  hypochlorous  acid  it 
should  be  discarded.  Fresh  solutions,  if  chilled,  may  temporarily 
become  cloudy  or  even  precipitate,  owing  to  the  separation  of  either 
dichloramin-T  or  solid  paraffin.  Slightly  warming  the  solution  quickly 
restores  its  usefulness. 


Fig.  358. — Office-preparation  bottle. 

For  office  purposes  it  is  best  to  keep  the  dichloramin-T  solution  in  an 
amber-colored  office-preparation  bottle  with  a  ground  cap  (Fig.  358). 
A  small  glass  rod  or  tube  kept  in  the  bottle  readily  assists  in  obtaining 
the  few  drops  necessary  for  each  treatment,  to  be  placed  upon  an 
aseptic  glass  tray.  Under  no  condition  should  pliers  charged  with 
cotton,  etc.,  be  introduced  into  the  preparation  in  the  bottle,  and  no 
unused  portions  of  the  solution  should  be  returned  to  the  stock-bottle. 

Dichloramin-T  shares  with  other  chlorin  compounds  the  property  of 
being  a  very  active  lymphagogue,  i.  e.,  the  amount  of  wound  secretion, 
especially  in  the  beginning  of  the  treatment,  may  be  considerably 
increased.  The  author's  attention  has  been  frequently  drawn  to  this 
fact  by  fellow-practitioners  who  have  tried  the  compound  in  treating 
root  canals  and  who  complained  of  the  increased  secretions  from  the 
canals,  which,  incidentally,  influences  the  granulation  of  the  wound 
most  beneficially. 

The  application  of  the  antiseptic  principle  as  utilized  in  wound 
sterilization  depends  primarily  upon  three  definite  conditions: 

1.  Absolute  contact  of  the  antiseptic  with  the  infecting  organism. 
27 


418  TREATMENT  OF  INFECTED  ROOT  CANALS 

2.  Time  during  which  this  contact  is  maintained. 

3.  Sufficient  concentration  of  the  antiseptic  at  the  point  of  contact. 
Absolute  contact  between  the  antiseptic  agent  and  the  substances  to 

be  acted  upon  must  be  rigidly  observed,  as  no  antiseptic  is  known  to 
act  at  a  distance. 

Finally  the  permissible  concentration  of  the  antiseptic  depends 
largely  upon  the  tolerance  of  the  tissues  with  which  it  is  brought  in 
contact,  and  is  usually  obtained  from  clinical  observation.  The  con- 
centration of  the  antiseptic  solution  determines  its  mass  action,  which 
can  be  safely  employed  for  tissue  sterilization  (Fig.  359). 

After  the  root  canal  has  been  suitably  prepared  by  mechanical  and 
chemical  means,  so  as  to  present  a  conical  shaped  tube,  a  freshly  flamed 
wire  is  inserted  to  the  very  apex  and  bent  so  as  to  form  a  shoulder 
near  the  pulpal  wall  and  a  roentgen  picture  is  taken.  The  tooth  is 
again  placed  under  a  rubber  dam,  the  wire  is  removed  and  the  canal  is 


Fig.  359. — Aseptic  medicament  tray. 

washed  with  sterile  water  and  dried  out.  Sterile  paper  points  assisted 
by  a  few  drops  of  acetone  or  absolute  alcohol  and  warm  air  are  service- 
able for  this  purpose.  Fair  dryness  of  the  canal  must  be  insisted  upon, 
as  otherwise  the  future  treatment  with  dichloramin-T  is  materially 
impaired. 

A  suitable  paper  point  is  now  saturated  with  dichloramin-T,  carried 
to  the  root  canal  and  with  a  pumping  motion  an  attempt  is  made  to 
coat  the  walls  of  the  latter,  and  if  possible  a  drop  is  forced  into  the 
periapical  space.  The  use  of  the  warm  air  blast  is  of  material  assistance 
in  getting  the  oily  solution  into  the  finer  ramifications  of  the  canal. 
The  warm  air  blast  is  recommended  in  this  connection  solely  for  its 
mechanical  effect  in  aiding  the  diffusion  of  the  dichloramin-T  through- 
out the  dentin.  The  natural  moisture  present  in  the  tooth  structure 
will  assist  in  the  production  of  the  nascent  chlorin  from  the  reaction  of 
the  dichloramin-T  with  the  water  of  the  organic  structure  of  the  tooth. 

A  fresh  point  carrying  a  drop  or  two  of  the  chlorin  solution  is  now 


ELECTRO-STERILIZATION  419 

slowly  forced  into  the  canal  to  its  very  end  and  immediately  sealed 
with  a  suitable  retainer.  As  we  have  stated  above,  close  contact  of  the 
antiseptic  solution  with  the  walls  of  the  root  canal,  and  if  possible  with 
the  surface  of  the  involved  infected  area  within  the  periapical  tissues, 
is  essential  to  obtain  therapeutic  results.  The  first  application  remains 
undisturbed  for  twenty-four  hours.  At  the  return  of  the  patient  the 
point  is  removed  aseptically  and  carefully  examined. 

A  second,  a  third  or,  on  rare  occasions,  a  fourth  dichloramin-T 
treatment  is  placed  in  the  dry  canal  and  these  applications  again  remain 
respectively  undisturbed  for  twenty-four  hours.  The  paper  cone 
removed  at  the  last  sitting  must  show  no  discoloration;  it  must  have  a 
distinct  odor  of  chlorin  and  not  of  hypochlorous  acid  and  it  must  be 
fairly  free  from  absorbed  exudates.  If  possible  the  treatments  should 
not  be  left  in  the  canal  over  twenty-four  hours;  at  the  end  of  this  time 
the  chlorin  compound  is  completely  exhausted  and  usually  a  flow  of 
lymph,  as  referred  to  above,  is  the  sequence.  Should  the  flow  of  lymph 
be  rather  copious  a  dry,  sterile  paper  cone  may  be  inserted  for  a  day  or 
two  under  a  hermetical  seal;  usually  normal  conditions  of  the  periapical 
tissues  will  speedily  return.  If  at  the  last  treatment  the  canal  is  found 
satisfactorily  clean  a  microscopic  examination  in  the  form  of  a  smear 
obtained  from  the  removed  cone  is  made.  If  the  examination  indicates 
sterility  no  time  should  be  lost  in  filling  the  canal  at  once. 

Regarding  the  existing  sterility  of  a  primarily  infected  root  canal 
as  treated  by  the  above-outlined  dichloramin-T  method,  it  should  be 
emphasized  that  rigorous  bacteriologic  tests  were  made  in  numerous 
instances  in  the  routine  way  by  plating  out  scrapings  by  incubation 
upon  agar  plates  in  bouillon,  etc.  After  exposure  in  an  incubator  for 
various  lengths  of  time,  usually  from  forty-eight  to  seventy-two  hours, 
it  was  observed  that  bacterial  growth  from  the  previously  infected 
canals  was  negative,  i.  e.,  no  cultures  were  obtained  usually  after  the 
third,  and,  in  a  few  cases,  after  the  fourth  treatment. 

ELECTRO-STERILIZATION. 

When  a  solid,  a  liquid  or  a  gas  enters  into  solution  and  is  capable  of 
conducting  an  electric  current,  according  to  Arrhenius,  the  solution 
undergoes  certain  changes  which  are  grouped  under  the  generic  term 
electrolysis.  This  latter  term,  with  the  following  nomenclature,  was 
introduced  by  the  English  physicist  Faraday  (1791-1867)  and  is  still 
generally  employed.  The  solution  itself  is  known  as  the  electrolyte 
while  the  dissociated  products  are  referred  to  as  ions.  The  terminals 
at  which  the  electric  current  enters  or  leaves  the  electrolyte  are  called 
electrodes.    An  ion  (ion  =  going)  ma^y  be  referred  to  as  being  the  dis- 


420  TREATMENT  OF  INFECTED  ROOT  CANALS 

sociated  product  of  a  chemical  decomposition  which  is  capable  of  con- 
ducting an  electric  charge  and  which  travels  in  the  direction  of  an 
oppositely  charged  pole.  Those  ions,  which  are  charged  negatively, 
migrate  to  the  anode,  i.  e.,  the  positive  pole,  and  are  known  as  anions, 
while  the  positively  charged  ions  migrate  to  the  negative  pole,  the 
cathode  and  are  known  as  cations.  Relatively  speaking,  all  metals, 
alkaloids  and  hydrogen  are  positive  ions,  i.  e.,  cations,  while  all  acids, 
bases,  halogens,  hydroxyl  compounds  and  oxygen  are  negative  ions, 
i.  e.,  anions. 

As  Ostwald  has  suggested  the  cation  may  be  designated  by  the  posi- 
tive sign  +  or  by  • ,  and  the  anion  by  the  negative  sign  —  or  by  '  . 
"An  ion  may  be  either  a  charged  atom,  as  in  the  case  of  the  silver  ion,  or 
a  charged  group  of  atoms  or  molecules.  In  the  case  of  silver  nitrate 
AgNOs  the  cation  is  Ag  and  the  anion  is  the  molecule  or  radicle  NO3. 
The  charge  of  the  NO3  ion  is  one  negative  unit  and  that  of  the  Ag  ion 
is  one  of  positive  unit,  as  both  the  ions  are  monads  or  monatomic." 
(Lewis  Jones.) 

A  simple  solution  of  salt  in  water  dissociates  the  salt  into  electro^ 
molecules,  the  ions,  which  exist  independently  of  the  action  of  a  gal- 
vanic current.  The  number  of  positively  and  negatively  charged  ions 
is  equimolecular,  i.  e.,  the  solution  is  electrically  neutral.  The  ions 
themselves  are  suspended  in  the  solution  in  a  chaotic  mixture.  The 
passing  of  the  galvanic  current,  according  to  Nernst,  by  its  electro- 
motive force,  causes  a  definite  movement  of  the  ions  in  an  orderly 
direction  to  their  specific  centers  of  attraction,  ^.  e.,  respectively  to  the 
positive  and  the  negative  poles. 

The  degree  of  concentration  of  the  solution  to  be  ionized  has  no  effect 
upon  the  number  of  ions  produced;  the  latter  depends  upon  the  strength 
of  the  current  multiplied  by  the  time  for  which  it  is  applied.  In  other 
words,  ionization  is  a  manifestation  of  transformed  electric  energy  in 
accordance  with  Faraday's  law.  The  amount  of  decomposition  of  an 
electrolyte  is  proportional  to  the  amount  of  electricity  which  flows 
through  it. 

The  process  of  electro-sterilization  of  infected  root  canals  concerns 
itself  primarily  with  the  disinfectant  action  of  the  liberated  ions  and 
less  so  with  their  supposed  medicinal  qualities.  The  disinfectant  action 
is  principally  confined  to  the  surface  of  the  object  treated,  although  a 
certain  depth  of  penetration  is  desirable. 

The  electric  current,  per  se,  at  least  in  the  strength  suitable  for  root 
sterilization,  does  not  produce  any  measurable  bactericidal  action.  A 
weak  current  passed  for  hours  through  diluted  sulphuric  acid  prior  to 
entering  an  inoculated  Petri  dish  does  not  inhibit  the  growth.  In 
the  presence  of  an  electrolyte  the  current  acts  on  the  dissociated  ions 


ELECTRO-STERILIZATION 


421 


of  the  latter,  and,  depending  upon  their  specific  chemical  nature,  some 
of  the  most  powerful  disinfectants  may  be  obtained.  It  is  claimed 
that  certain  pure  metals  as  such  possess  slight  antiseptic  action.  This 
property  was  first  observed  by  the  late  Professor  Miller.  According 
to  Behring  this  antiseptic  action  is  the  result  of  the  reaction  of  certain 
waste  products  of  bacteria,  primarily  lactic  acid,  with  those  metals 
which  are  capable  of  forming  soluble  salts  and  which  diffuse  through  the 
medium.  This  antiseptic  action  of  metals  must  not  be  confounded 
with  the  oligo-dynamic  action  of  certain  pure  metals  in  their  colloidal 


Fig.  360. — Long-handle  electrode  with  iridio- 
piatiniim  point. 


Fig.  361. 


-Insulated  electrode 
holder. 


state,  as  copper,  for  instance,  on  low-type  plant  cells.  Of  the  pure 
metals,  according  to  the  classic  experiments  made  by  Thiele  and  Wolf, 
mercury,  silver  and  copper  are  the  only  ones  which  produce  poisonous 
salts  in  the  presence  of  bacteria,  while  the  other  tested  metals,  i.  e.,  plati- 
num, palladium,  gold,  aluminum,  magnesium,  zinc,  lead,  tin  and  iron 
are  wholly  devoid  of  action.  In  the  discussion  of  electro-sterilization 
of  infected  root  canals  great  stress  is  frequently  laid  by  certain  men 
upon  the  specific  nature  of  the  metallic  electrode  placed  in  the  root 
canal  as  being  the  factor  which  produces  the  desired  germicidal  effect. 


422  TREATMENT  OF  INFECTED  ROOT  CANALS 

Rheim,  for  instance,  insists  on  using  a  chemically  pure  zinc  electrode 
in  the  presence  of  a  sodium  chlorid  solution,  claiming  that  "nascent 
zinc  chlorid"  is  formed  during  the  process  of  electrolysis.  Other 
practitioners  employ  a  copper  electrode  and  a  weak  zinc  chlorid  solu- 
tion as  a  substitute  for  the  sodium  chlorid  solution.  A  zinc  electrode 
employed  for  electro-sterilization  of  root  canals  is  not  onl}'  devoid  of 
any  germicidal  action,  but  it  is  also  an  ill-chosen  metal  for  this  purpose, 
because  a  zinc  wire  is  too  brittle  to  be  filed  fine  enough  to  readily  enter 
a  minute  root  canal  without  inviting  danger  of  breaking  (Figs.  360  and 
361). 

Ionization  of  a  metallic  electrode  occurs  primarily  in  the  presence  of  a 
suitable  electrolyte,  i.e.,  a  solution  of  a  salt  of  the  metal  of  the  respective 
electrode.  While  theoretically  it  is  true  that  ions  of  the  respective 
electrode  must  be  produced  as  a  secondary  sequence  of  the  primary 
ionization  of  the  electrolyte,  practically,  in  employing  the  low  amperage 
tolerated  by  the  human  body  these  ions  are  not  demonstrable  with  the 
ordinary  chemical  reactions,  consequently  they  cannot  exercise  any 
therapeutic  effect.  A  zinc  electrode  in  the  presence  of  a  sodium  chlorid 
solution  is  not  ionized  in  the  short  space  of  time  and  with  the  low  amper- 
age employed  in  the  electro-sterilization  of  root  canals,  consequently 
"nascent  zinc  chlorid"  ions,  which  are  believed  to  have  been  produced 
from  zinc  electrodes,  are  imaginary  therapeutic  bodies.  When  a  high 
amperage  is  employed  in  experimental  work  outside  of  the  human 
body,  sufficient  hydrochloric  acid  is  obtained  as  a  secondary  product 
which  will  act  on  the  zinc  pole,  forming  zinc  chlorid. 

The  Electric  Current  and  Its  Accessories. — ^The  only  current  suitable 
for  electro-sterilization  is  the  direct  current.  The  alternating  current 
cannot  be  used  unless  it  is  changed  by  a  transformer.  This  may  be 
accomplished  by  a  chemical  "rectifier"  or  a  small  motor  dynamo. 
The  chemical  rectifier  without  potential  equalizer  has  not  been  found 
satisfactory  by  the  author.  The  source  of  the  current  may  be  obtained 
from  the  main  line,  from  an  accumulator  or  a  storage  battery  or  from 
a  series  of  cells.  If  the  street  current  is  used  it  must  be  reduced  by  a 
rheostat  to  about  30  to  40  volts.  A  number  of  lamps,  mounted  in 
series,  one  lamp  of  sufficiently  high  voltage,  or  a  wire  rheostat,  is 
usually  employed  for  this  purpose.  An  ordinary  switchboard  is  less 
suitable,  as  there  is  always  danger  of  shocking  the  patient  through 
imperfect  control  (Fig.  362).  If  the  street  current  is  used  a  knife 
switch  should  be  interposed  between  the  rheostat  and  the  current 
controller.  If  cells  are  employed — and  many  practitioners  and  most 
of  the  reliable  electric  supply  houses  regard  a  cell  series  as  the  safest 
means  for  the  purpose  in  view — about  18  to  24  Leclanche  wet  cells  or 
an  equal  number  of  ordinary  dry  cells   (Columbia  No.  6)  are  most 


ELECTRO-STERlLIZA  TION 


m 


Useful  (Fig.  363).     Tlie  silver  chloric!  cell  is  less  serviceable  for  our 
purpose.     x\n  ordinary  wet  or  dry  cell  furnishes  approximately  a  little 


Fig.  362. — Switchboard  for  electro-sterilization.     (Mcintosh.) 


Fig.  363. — -Galvanic  battery  for  electro-sterilization. 


424 


TREATMENT  OF  INFECTED  ROOT  CANALS 


over  one  and  a  half  volts.  Recently,  compact  types  of  dry-cell  batteries 
furnishing  a  current  of  very  low  amperage  and  medium  voltage, 
intended  for  wireless  telegraphy,  have  been  placed  on  the  market. 


Fig.  364.— The  S.  S.  White  current  controller. 

These  cells  are  mounted  in  series  and  connected  to  binding-posts. 
From  these  posts  the  current  is  conveyed  by  means  of  flexible  conduct- 
ing cords  to  a  suitable  controller  (Fig.  364).  The  most  important 
feature  of  a  serviceable  controller  consists  in  the  gradual  increase  or 


Fig.  365. — Weston  milliamp^remeter. 


decrease  of  the  current  in  very  small  fractions  of  a  milliampere  without 
shocking  the  patient.  A  graphite  or  a  series  wire  rheostat,  either 
plain  or  as  a  shunt,  is  serviceable  for  such  purposes.    The  markings 


ELECTRO-STERILIZATION  425 

on  the  current  controller,  be  they  volts  or  arbitrary  numbers,  have  little 
bearing  on  the  practical  application  of  the  current. 

The  current  controller,  in  turn,  is  connected  with  a  milliampere- 
meter,  an  instrument  for  measuring  the  quantity  of  strength  of  the 
current  (Fig.  365).  The  milliamperemeter  is  the  instrument  of  preci- 
sion which  guides  the  operator  in  his  work,  consequently  too  much 
emphasis  cannot  be  placed  upon  the  importance  of  obtaining  a  perfect 
working  instrument. 

At  this  point  the  author  may  be  permitted  to  digress  for  a  moment 
from  the  subject  proper  and  call  to  the  mind  of  the  reader  the  funda- 
mental nomenclature  governing  electrical  measurements — as  far  as  it  is 
utilized  in  the  following  discussion.  By  the  term  ampere  is  meant  the 
unit  of  strength  of  a  current.  A  milliampere  is  a  thousandth  part  of 
an  ampere,  expressed  as  MA.  A  volt  is  the  measure  of  the  unit  of 
pressure  of  the  current,  i.  e.,  the  electric  power  necessary  to  drive  a 
current  of  one  ampere  through  a  resistance  of  one  ohm.  It  is  referred 
to  as  the  electromotive  force  and  expressed  as  E.  M.  F.  An  ohm 
measures  the  resistance  of  a  circuit  through  which  a  current  flows. 

From  the  above  explanation,  as  related  to  the  process  of  electro- 
sterilization,  it  is  obvious  that  the  correct  measurement  of  the  amount 
of  current  applied  to  a  patient  is  of  the  utmost  importance,  as  it  is 
the  safest  means  of  guiding  us  during  its  application.  Hence  the  impor- 
tance of  procuring  a  trustworthy  milliamperemeter.  The  best  instru- 
ments are  those  constructed  after  the  Deprez-d'Arsonval  deadbeat 
(non-trembling)  type.  The  Weston  milliamperemeter  is  a  most  reliable 
current  gauge.  The  face  of  the  latter  instrument,  suitable  for  this 
work,  should  be  calibrated  into  5  milliamperes,  with  subdivisions  of  a 
tenth  to  a  twentieth  of  a  milliampere.  To  convey  the  current  to  the 
patient,  different  colored  flexible  cords  are  employed  which  terminate 
in  suitable  electrodes  (Fig.  366) .  In  connecting  up  the  whole  apparatus 
extreme  care  must  be  observed  in  joining  equal  poles  to  each  other, 
namely,  positive  pole  must  be  connected  to  positive  pole,  and  vice 
versa.  To  locate  the  respective  poles  the  following  simple  experiment 
may  be  employed.  Moisten  a  piece  of  blue  litmus  paper  with  water, 
place  the  two  poles  of  the  battery  about  one  inch  apart  on  the  wet 
paper  and  turn  on  the  current.  In  a  few  moments  a  pink  spot  will 
develop  where  the  ■positive  pole  touches  the  paper. 

The  two  electrodes  are  terminals  attached  for  the  purpose  of  convey- 
ing the  current  to  the  patient,  and  consist  of  a  negative  electrode 
which  is  to  be  placed  on  the  patient's  skin  surface,  and  a  positive 
electrode  to  be  introduced  into  the  tooth.  The  negative  electrode 
may  be  a  piece  of  metallic  tubing  held  firmly  in  the  patient's  hand,  or  a 
sponge  electrode  fastened  to  his  wrist,  or  one  of  various  modifications 


426 


TREATMENT  OF  INFECTED  ROOT  CANALS 


thereof.  The  size  of  the  negative  hand  electrode  is  important;  it 
should  present  at  least  five  square  inches  of  surface  area,  which  are  to 
be  brought  into  contact  with  the  patient.  A  large  surface  of  the  nega- 
tive electrode  reduces  the  resistance,  and  consequently  the  tingling 
sensation  6v  even  blistering  caused  by  the  heat  of  a  small  electrode  is 


Fig.  366. — Metal  negative  hand  electrode. 


avoided.  The  author  prefers  the  plain  tube  hand  electrode,  as  it 
avoids  the  cumbersome  wetting  with  salt  water,  loss  of  time  in  adjusting 
it,  etc.  It  is  immaterial  in  which  hand  the  electrode  is  held.  Rings, 
bracelets,  wrist  watches,  etc.,  must  be  removed,  otherwise  blistering 
of  the  patient's  skin  by  mere  contact  may  occur.     Placing  the  negative 


ELECTRO-STERILIZATION  427 

electrode  upon  the  patient's  cheek,  lip  or  giun  surface  by  means  of  a 
clamp  or  spring,  as  recommended  by  some  operators,  is  to  be  avoided, 
for  the  reason  that  severe  burns  may  result.  It  has  been  stated  that 
this  blistering  results  from  the  formation  of  caustic  sodium  hydroxid 
near  the  negative  pole.  The  blistering  is  the  result  of  imperfect 
contact  between  the  skin  and  the  metal  electrode,  thereby  increasing 
the  resistance  of  a  small  area  to  such  an  extent  as  to  produce  high  heat, 
i.  e.,  an  electric  burn.  The  positive  electrode  to  be  introduced  into  the 
tooth  consists  of  a  piece  of  iridio-platinum  wire,  No.  20  gauge,  about 
one  inch  long  and  tapered  to  a  delicate  point.  The  iridio-platinum 
alloy  possesses  the  necessary  flexibility,  which  is  lacking  in  pure  plati- 
num. The  point  itself  is  ground  blunt  so  as  to  avoid  being  caught 
when  introduced  into  tortuous  canals.  Various  sizes  of  these  points 
may  be  kept  on  hand.  No  other  metal  should  be  employed  for  such 
purposes.  To  substitute  the  iridio-platinum  point  by  zinc,  copper  or 
any  other  metal,  with  the  view  of  aiding  its  therapeutic  effects  is  not 
only  useless,  but  markedly  interferes  with  the  action  of  electrolysis  in 
the  relatively  sm.all  area  of  a  root  canal  and  the  resultant  ions  may  dis- 
color the  tooth.  A  long-handle  electrode  holder,  insulated  with  hard 
rubber,  is  essential  to  suitably  unite  the  electrode  with  the  conducting 
cord.  The  holders  ma}'  be  of  various  types  so  as  to  give  ready  access 
to  all  parts  of  the  oral  cavity.  From  the  foregoing  description  of  the 
source  of  the  current,  its  control  and  its  mode  of  application,  it  may 
be  observed  that  essentially  it  is  a  duplicate  of  the  armamentarium  as 
applied  in  producing  cataphoresis.  Any  apparatus,  therefore,  that  is  or 
has  been  used  for  inducing  cataphoresis  may  be  equally  successfully 
employed  for  the  electro-sterilization  of  root  canals. 

Electro-sterilization  Equation. — ;In  the  various  communications  treat- 
ing on  root  sterilization  by  electrolysis  the  very  important  questions 
concerning  the  time  during  which  the  current  is  applied,  the  number 
of  milliamperes  employed  and  hacteriologic  tests  of  the  resultant 
sterility  are  usually  vaguely  treated.  When  sterility  of  a  primarily 
infected  root  canal  is  spoken  of  in  the  present  light  of  hacteriologic 
knowledge  the  truth  of  this  assertion  has  to  be  proved  by  rigorous 
tests,  otherwise  the  term  sterility  loses  its  significance.  These  tests 
are  readily  made  b}^  obtaining  cultures  at  stated  intervals  from  the 
canal  under  treatment  until  complete  negative  results  of  growth  are 
obtained.  Regarding  the  hacteriologic  tests  as  applied  to  electro- 
sterilization,  the  author  proceeded  as  follows :  cultures  of  the  infected 
root  canal  were  made  before  treatment  was  instituted  and  then  every 
five  minutes  thereafter  for  a  given  period  of  time,  usually  twenty 
minutes.  The  infected  agar  plates  were  incubated  in  the  routine 
manner.     Incidentally  the   time   of   applying  the   current  and    its 


428  TREATMENT  OF  INFECTED  ROOT  CANALS 

strength  were  carefully  noted.  By  comparing  the  results  obtained 
a  definite  relationship  between  the  strength  of  the  current,  the 
time  of  application  and  the  resultant  sterility  could  be  established. 
Zierler  deserves  credit  for  having  first  noted  the  interrelationship  of 
these  factors,  and  he  has  suggested  the  use  of  a  numerical  constant 
which  furnishes  a  working  basis  for  its  clinical  application.  This 
constant  is  30.  By  multiplying  the  number  of  milliamperes  employed 
by  the  time  in  minutes  used  in  the  process  of  obtaining  a  sterile  root 
canal,  invariably  a  number  was  obtained  which  closely  hovered  about 
the  figure  30;  or,  reversely,  by  dividing  the  constant  30  by  the  number 
of  milliamperes  employed  a  quotient  is  obtained  which  gives  the  time 
in  minutes  during  which  the  current  must  be  applied.  Apparently 
a  given  infected  surface  area  requires  for  its  sterilization  a  specific 
amount  of  migrating  ions;  at  least  this  assertion  can  be  verified,  as  far 
as  the  germicidal  action  of  ionized  chlorin  is  concerned,  in  the  steriliza- 
tion of  infected  root  canals.  Hence  the  numerical  constant  30  may  be 
looked  upon  as  expressing  in  units  the  surface  area  of  an  average  root 
canal.  In  the  author's  experimental  work  and  in  clinical  practice  he 
has  based  his  observations  upon  the  above  principle  and  has  collected 
sufficient  data  as  proofs  that  the  appended  electro-sterilization  equation, 
as  this  formula  has  been  termed,  is  a  reliable  guide  for  the  application  of 
these  procedures  in  the  treatment  of  infected  root  canals;  30  MA  =  T, 
the  30  representing  the  numerical  constant,  MA  the  number  of  milliam- 
peres and  T  the  time  in  minutes. 

Clinical  Application  of  Electro-sterilization. — To  convey  to  the 
reader  a  practical  working  knowledge  of  the  clinical  application  of  the 
principles  of  electro-sterilization  it  is  probably  best  to  describe  the 
actual  modus  operandi  in  detail  as  employed  in  a  typical  case.  The 
patient  seated  in  the  chair  is  covered  with  a  rubber  apron  sufficiently 
large  to  reach  over  the  chair  arms,  so  as  to  protect  him  from  accidental 
shock  by  "grounding"  the  current.  The  root  canal  of  the  tooth  to  be 
treated  must  be  mechanically  cleansed  of  its  debris,  and  if  necessary 
enlarged  so  as  to  give  free  access  to  the  wire  electrode.  Before  starting 
the  ionizing  process  it  is  best  to  assure  one's  self  of  the  correct  working 
of  the  current  by  bringing  the  two  poles  together  for  a  moment;  the 
moving  of  the  needle  of  the  milliamperemeter  in  the  right  direction 
acts  as  an  indicator  that  the  apparatus  is  in  working  order.  The 
rubber  dam  having  been  adjusted  the  root  canal  is  now  flooded  with  a 
1  per  cent,  saline  solution — an  S.  S.  W.  minimum  syringe  is  useful  for 
such  purposes.  The  patient  takes  a  firm  hold  of  the  negative  electrode 
with  his  hand,  which  must  not  carry  rings,  bracelets,  etc.  Before 
introducing  the  freshly  flamed  positive  pole  into  the  canal  the  operator 
should  see  that  the  knife  switch  is  open,  and  that  the  controller  is 


ELECTRO-STERILIZATION  429 

set  at  zero.  If  the  wire  electrode  fits  the  canal  too  loosely  a  few 
fibers  of  cotton  moistened  with  salt  water  are  wrapped  about  it.  The 
needle  is  introduced  as  near  to  the  apex  as  possible  and  the  knife  switch 
is  closed.  The  controller  is  now  very  slowly  turned  on  and  the  patient 
is  told  to  at  once  raise  his  hand  when  he  feels  the  slightest  sensation. 
The  moving  needle  of  the  milliamperemeter  will  indicate  to  the  operator 
that  the  current  is  flowing  in  the  right  direction.  When  the  patient 
raises  his  hand  the  controller  is  turned  very  slightly  back,  left  at  this 
point  for  about  half  a  minute  and  again  very  slowly  turned  forward 
until  the  patient  again  responds  or  until  the  point  of  tolerance  is  estab- 
lished. This  point  the  author  has  termed  the  "irritation  point." 
A  glance  at  the  milliamperemeter  informs  the  operator  of  the  number  of 
milliamperes  employed.  The  operator  now  recalls  to  his  mind  the 
numerical  constant  30  and  quickly  calculates  the  time  of  his  particular 
case  of  electro-sterilization  by  dividing  thirty  by  the  number  of  milli- 
amperes employed.  The  resultant  quotient  gives  the  time  in  minutes 
for  which  the  current  must  be  applied.  Example:  if  the  patient's 
irritation  point  is  2.5  MA,  twelve  minutes  by  the  watch  are  required  for 
the  sterilization  of  this  particular  root  canal.  If  the  resultant  quotient 
is  a  fraction  the  author  recommends  that  the  next  higher  unit  be  sub- 
stituted as  the  indicator  of  the  time.  Each  root  canal  of  a  multi- 
rooted tooth  is  preferably  treated  separately.  If  a  clamp  electrode 
holder  is  employed  to  clasp  the  two  or  three  wires  inserted  into  the 
multirooted  tooth  care  should  be  exercised  to  prevent  short-circuiting. 
To  avoid  polarization  of  the  positive  electrode,  i.  e.,  covering  by  a  film 
of  nascent  gases  which  materially  interferes  with  the  flow  of  the 
current,  the  needle  should  be  removed  at  five-minute  intervals  (turn 
off  current  previously!)  and  wiped  off.  During  the  process  of  electro- 
sterilization  a  drop  of  salt  water  should  be  added  about  every  minute 
to  make  up  for  loss  by  evaporation.  Care  must  be  exercised  to 
prevent  short-circuiting  of  the  current  by  allowing  salt  water  to  seep 
under  the  rubber  dam  and  thus  transfer  the  current  to  the  gum  tissue. 
After  finishing  the  operation  the  controller  is  slowly  turned  to  zero,  the 
knife  switch  is  opened  and  the  electrode  removed  from  the  tooth. 
Never  remove  the  electrode  without  having  first  cut  off  the  current, 
otherwise  the  patient  receives  a  disagreeable  shock  or  a  flash  of  light 
passing  in  the  eyes.  On  passing  a  few  fibers  of  cotton  or  a  paper  cone 
in  the  root  canal  a  pronounced  odor  of  chlorin  should  be  perceptible. 
A  wisp  of  cotton  or  a  cone  wet  with  salt  water  is  placed  in  the  root 
canal  and  the  latter  is  closed  with  gutta-percha  stopping.  The 
treatment  is  to  be  repeated  within  twenty-four  hours,  and  if  necessary 
again  on  the  third  day,  and  the  canal  is  immediately  filled  after  the 
last  treatment.  A  root  canal  should  never  be  filled  immediately  after 
the  initial  treatment;  an  interval  of  at  least  twenty-four  hours  should 


430  TREATMENT  OF  INFECTED  ROOT  CANALS 

be  allowed  before  doing  so.  Migrating  ions  do  not  develop  their 
maximum  degree  of  therapeutic  efficiency  within  the  short  period  of 
time  during  which  the  current  is  applied.  It  requires  practically 
twenty-four  hours  to  produce  their  full  activity  within  the  region  of  a 
root  canal  and  its  surroundings.  The  clinical  indications  of  complete 
sterility  are  definite  odor  of  chlorin  and  a  clean  paper  or  cotton  cone 
after  twenty-four  hours'  insertion.  In  doubtful  cases  sterility  should 
be  verified  by  a  bacteriologic  test.  If  a  metal  filling  is  present  in 
the  tooth  under  treatment  it  should  be  removed,  because  if  touched  by 
the  electrode  after  the  current  is  turned  on  it  may  be  short-circuited 
through  the  filling  and  the  patient  will  receive  a  shock.  Moreover  the 
action  of  the  chlorin  ions  upon  the  metals  of  the  filling  materials  results 
in  the  formation  of  metallic  chlorids,  which  infiltrate  the  dentin 
structure,  producing  discoloration.  This  is  particularly  true  in  the 
case  of  gold  chlorid  thus  formed,  which  by  secondary  decomposition 
stains  the  tooth  structure  a  deep  purple  tint. 

When  the  products  of  pulp  decomposition  pass  beyond  the  foramen 
of  a  tooth,  localized  pathologic  disturbances  of  the  pericementum, 
arise,  which  usually  lead  to  the  formation  of  an  abscess.  Without 
entering  into  the  further  discussion  of  the  pathology  of  the  disturbances 
at  this  moment,  let  us  assume  that  the  disturbances  are  eradicated  by 
establishing  drainage  along  the  lines  of  least  resistance.  If  the  drainage 
takes  place  through  the  root  canal  this  condition  is  spoken  of,  although 
wrongly,  as  a  blind  abscess,  while  if  the  drainage  occurs  through  an 
artificially  established  canal  through  the  bone  and  gum  tissue  a  fistula 
results.  Acute  types  of  the  enumerated  disturbances  yield  readily 
to  electro-sterilization,  provided  the  salt  solution  and  the  positive 
electrode  reach  the  seat  of  the  infection.  For  the  treatment  of  an 
abscess  draining  through  the  root  canal  the  positive  electrode  is  thrust 
through  the  foramen  into  the  abscess  cavity;  the  treatment  of  an 
abscess  with  a  fistula  requires  a  somewhat  modified  application.  In 
the  latter  case  complete  communication  between  the  root  canal  and  the 
mouth  of  the  fistula  must  be  first  established  by  forcing  warm  salt 
water  through  the  canal.  The  root  canal  is  now  treated  as  outlined 
above;  the  fistula  itself  requires  a  separate  application  of  the  procedure. 
The  positive  electrode  is  passed  into  the  fistula,  entering  at  its  outlet 
and  carried  along  the  fistulous  tract  until  the  root  is  felt,  while  the 
negative  pole,  consisting  of  a  piece  of  copper  wire  surrounded  by  salt 
water,  is  placed  in  the  root  canal.  The  sterilization  equation  for  this 
treatment  is  the  same  as  already  outlined.  Usually  the  patient  requires 
a  lower  milliamperage  for  such  work.  All  types  of  chronic  abscesses 
will  yield  to  this  method  of  treatment,  provided  the  necrotic  area 
involved  is  very  small  and  that  the  seat  of  disturbance  is  reached  hj  the 
pl^ctrode  and  by  the  salt  watey , 


CHAPTER  IX. 

THE  PREPARATION  AND  FILLING  OF  ROOT  CANALS.^ 

By  EDGAR  D.  COOLIDGE,  D.D.S. 

Introduction. — There  never  has  been  a  time  when  a  greater  or  more 
vital  problem  confronted  the  dental  profession  than  the  present  one 
in  the  proper  handling  of  pulpless  teeth.  The  one  extreme  practice  of 
extracting  all  pulpless  teeth  or  the  other  extreme  of  retaining  all  teeth 
regardless  of  the  condition  of  the  peridental  membrane  and  alveolar 
process  about  their  roots  is  not  the  best  service  to  mankind.  There  are 
many  teeth  being  extracted  which  should  be  properly  treated  and  the 
roots  filled  and  at  the  same  time  some  of  the  profession  are  failing  to 
recognize  the  danger  to  the  general  health  of  the  patient  in  retaining 
badly  infected  teeth  involving  the  periapical  tissue.  The  difficulties 
encountered  in  the  operation  of  pulp  removal  and  filling  root  canals  of 
most  teeth  are  weighing  down  upon  the  profession  and  as  a  result  the 
tendency  to  extract  teeth  requiring  root-canal  operations  is  becoming 
too  general.  The  tooth  which  is  saved  by  good  root-canal  filling  is 
usually  able  to  render  a  service  to  the  patient  unequaled  by  an  artificial 
substitute.  It  requires  much  patience  and  skill  coupled  with  persever- 
ance to  accomplish  good  results  in  root-canal  filling  and  the  operator 
who  acquires  these  characteristics  and  takes  advantage  of  the  improved 
equipment  and  the  higher  standards  of  excellence  in  this  work  will 
doubtless  have  a  degree  of  success  in  proportion  to  his  effort. 

EQUIPMENT  FOR  ROOT-CANAL  OPERATIONS. 

The  equipment  for  root-canal  operations  may  be  grouped  for  con- 
venience under  the  following  headings: 
Sterilizers. 
Root  canal  instrument  cabinet. 

1  Credit  is  hereby  given  to  those  in  whose  minds  many  of  the  ideas  herein  expressed 
originated  or  were  developed.  The  continued  study  of  the  most  excellent  chapters  on 
root  canal  operations  in  the  two  books:  "Operative  Dentistry"  and  "Special  Dental 
Pathology"  by  Dr.  G.  V.  Black  has  been  the  guiding  light  in  my  efforts  to  successfully 
fill  root-canals.  Dr.  Black's  minute  description  of  dental  anatomy  and  his  detailed  and 
most  complete  exposition  of  the  operations  on  root  canals  have  been  of  immeasiu-able 
benefit  to  the  dental  profession  in  standardising  root-canal  operations  and  the  greatest 
tribute  to  his  work  is  the  fact  that  hupdredp  of  dentists  are  attempting  to  follow  his 
teaching. 

(43;) 


432  PREPARATION  AND  FILLING  OF  ROOT  CANALS 

Supply  bottles. 
Containers. 
Cotton  supply. 
Burs  and  broaches. 
Pluggers. 
Filling  materials. 
Operating  tray. 
Sterilizers. — Sterilization  may  be  accomplished  by  the  following 
methods : 

Boiling.  Dry  heat. 

Steam.  Disinfectant  drugs. 


Fig.  367. — Dry  heat  sterilizer.  Automatic  control  makes  it  possible  to  maintain  any 
degree  of  temperature  from  200°  F.  to  350°  F.  for  an  indefinite  period.  A  temperature 
of  230°  F.  will  sterilize  in  ten  minutes,  with  a  higher  degree  of  temperature  less  time  is 
required,  and  with  a  lower  temperature  the  time  must  be  lengthened  proportionately. 
Especially  useful  for  cotton,  absorbent  points,  gutta-percha  cones,  napkins,  dressings,  etc. 

The  first  equipment  for  root-canal  operations  is  a  sterilizer  that  is 
practical  and  efficient.  For  the  sterilization  of  metal  instruments 
most  any  water  heater  in  which  instruments  can  be  conveniently  boiled 
for  at  least  twenty  minutes  answers  the  purpose  for  sterilizing  by  boiling 
and  there  are  many  satisfactory  makes  available  for  the  particular 
needs  of  every  office.  The  sterilization  of  dressings,  cotton,  towels  and 
other  root-canal  materials  has  become  a  necessity  for  the  dental  office 
and  it  is  necessary  to  have  a  suitable  sterilizer  for  this  purpose  (Figs. 
367  and  368) .  Simplicity  is  an  important  item  in  the  construction  and 
operation  of  a  sterilizer  for  dressings  and  other  materials  for  root  canal 


EQUIPMENT  FOR,  ROOT-CANAL  OPERATIONS 


433 


work.  If  the  operation  of  the  sterilizer  is  too  burdensome  or  there  is 
too  much  time  lost  in  sterilization  there  is  a  great  temptation  to  neglect 
this  most  important  procedure.     The  initial  cost  should  not  be  so  great 


Fig.  368. — Steam  chest  sterilizer.  Moist  heat  may  be  obtained  varying  from  190°  F. 
to_215°  F.  and  can  be  maintained  for  an  indefinite  period.  It  is  necessary  to  maintain 
this  temperature  at  least  thirty  minutes  and  is  safer  to  sterilize  three  successive  days 
before  using  the  materials  under  sterilization.  Especially  useful  for  materials  used  in 
root-canal  operations  as  Fig.  367. 

as  to  limit  the  use  of  proper  equipment  in  any  office.  There  are  some 
objections  to  boiling  broaches,  especially  those  with  barbs.  These 
may  be  subjected  to  dry  heat  at  230°  F.  for  ten  minutes  or  they  may  be 

28 


434  PREPARATION  AND  FILLING  OF  ROOT  CANALS 

immersed  in  a  10  per  cent,  solution  of  lysol  in  water  (Fig.  369).  For 
barbed  broaches,  root  files  and  surgical  knives  this  form  of  sterilization 
is  quite  satisfactory  if  all  organic  matter  and  debris  are  thoroughly 
cleansed  from  the  instruments  before  immersing  them  in  the  solution. 
The  solution  should  be  renewed  daily.     While  the  operation  is  under- 


FiG.  369. — ^B  id  die  broach  sterilizer.     Compartments  to  keep  broaches  separate  while  in 

lysol  solution. 

way,  broaches  should  be  immersed  in  95  per  cent,  phenol  followed  by 
alcohol  before  each  insertion  into  the  pulp  chamber  and  canal.  This 
necessitates  a  suitable  container  for  these  liquid  sterilizing  agents 
which  is  convenient  and  attractive.  The  container  or  medicament 
tray  (Fig.  370)  should  be  kept  before  the  operator  constantly  and  used 
for  the  purpose  of  maintaining  asepsis  of  the  broaches  during  the 


EQUIPMENT  FOR  ROOT-CANAL  OPERATIONS 


435 


operation.  It  is  quite  as  important  to  provide  against  contamination 
of  the  instruments  while  operating  as  it  is  to  start  with  sterile  instru- 
ments and  this  method  of  immersing  the  broach  is  simple  and  con- 
venient and  soon  becomes  a  matter  of  unconscious  habit. 


Fig.  370. — Medicament  tray.  Convenient  tray  with  compartments  for  phenol  and 
alcohol  to  sterilize  broaches  while  operating.  Other  compartments  for  other  drugs  and 
for  broaches. 


Root  Canal  Instrument  Cabinet. — The  equipment  for  root-canal 
operations  should  be  kept  separate  from  the  other  operating  instru- 
ments. The  large  instrument  cabinet  has  no  satisfactory  place  in 
which  to  keep  these  instruments  and  materials.  They  should  all  be 
kept  together  as  a  unit  in  a  small  cabinet  separated  from  all  other 
equipment  and  as  an  aseptic  precaution  should  be  constantly  subjected 


Fig.  371. — Root  canal  instrument  cabinet.  Air  tight  cabinet  for  formaldehyde 
sterilization.  Shelves  being  removable  make  convenient  operating  trays  with  complete 
equipment  for  operation  in  place. 


to  formaldehyde  to  maintain  sterilization  (Fig.  371).  The  cabinet 
shelves  should  be  removable  so  that  the  entire  contents  of  a  shelf  may 
be  taken  out  at  one  move  to  be  used  as  an  operating  tray  carrying  the 
entire  operating  unit.  This  shelf  containing  all  the  instruments  and 
materials  makes  an  ideal  aseptic  operating  tray  to  be  placed  upon  the 
bracket  before  the  operator. 


436 


PREPARATION  AND  FILLING  OF  ROOT  CANALS 


Supply  Bottles. — It  is  quite  necessary  to  have  a  stock  of  broaches 
sterilized,  ready  for  use  and  kept  within  easy  reach  while  operating, 
for  one  is  often  compelled  to  draw  upon  the  surplus  supply  during 
an  operation.     By  placing  the  stock  in  small  screw  top  glass  bottles 


Fig.  372. — Broach  bottles.     Screw  top  bottles  for  surplus  broach  supply. 
Broaches  sterilized  and  kept  ready  for  use. 

(Fig.  372)  the  operator  can  see  at  a  glance  when  the  stock  is  low  and 
order  before  the  supply  is  exhausted,  saving  much  inconvenience. 

The  drugs  which  are  regularly  used  may  be  kept  in  dropping  bottles 
to  save  time  and  inconvenience.     Glass  dropper  stoppered  bottles 


Fig.  373. — Glass  dropping  stoppered  bottles.     For  dropping  drugs  upon  the  medicament 
tray  instead  of  dipping  into  bottles. 


one-half  ounce  in  size  (Fig.  373)  make  very  satisfactory  containers  for 
daily  use.  The  habit  of  dipping  into  bottles  containing  drugs  should 
be  discontinued. 

Chloropercha  can  best  be  kept  in  a  small  bottle  with  a  glass  cap  top 


EQUIPMENT  FOR  ROOT-CANAL  OPERATIONS  437 

from  which  a  small  i)ortion  may  be  remo\'t'd  \vh.e]i  needed   for  the 
operation. 

Containers. — In  operating  in  root  canals  it  is  necessary  to  use  many 
small  instruments  of  different  sizes  as  well  as  several  drugs.  In  order 
to  accommodate  these  various  articles  during  the  operation  it  is  well 


Fig.  374. — Glass  container  for  gutta-percha  cones.      Gutta-percha  cones  cut  in  short 

lengths  ready  for  use. 

to  have  several  small  glass  or  porcelain  dishes  (minim  trays)  for  the 
broaches,  small  cups  for  different  drugs  for  use  during  the  operation 
thus  to  avoid  dipping  into  the  medicine  bottle.  A  suitable  dish  with 
compartments  for  different  sizes  and  lengths  of  gutta-percha  cones 
(Fig.  .374)  may  be  obtained  which  accommodates  these  various  pieces 
without  their  becoming  mixed,  thus  conserving 
the  operator's  time  as  they  should  always  be 
prepared  for  use  by  the  assistant  in  advance. 

The  Cotton  Supply. — The  cotton  supply  for 
root-canal  operations  should  include  sterile  cotton 
pellets  and  absorbent  paper  points  (Fig.  375). 
There  is  no  need  for  loose  cotton.  It  is  not 
necessary  to  wrap  cotton  upon  a  broach  since 
the  advent  of  the  absorbent  paper  point.  The 
method  of  keeping  cotton  constantly  before  one  in 
an  open  jar  and  rolling  it  with  the  fingers  should  _  ak     b  nt 

be  abandoned  because  it  is  not  aseptic  without  paper  point. 

sterilization  after  being  handled.  Sterilization  of 
cotton  wrapped  upon  a  broach  is  easily  overlooked  or  neglected,  hence  it 
is  far  safer  to  abandon  the  loose  cotton  than  to  attempt  to  sterilize  it 
after  wrapping  it  upon  the  broach.  When  the  broach  is  remo\ed  from 
the  canal  it  usually  carries  debris  or  organic  matter  which  must  be 
cleaned  from  it.  A  small  square  of  sterile  gauze  or  muslin,  five  inches 
each  way  fastened  to  a  corner  of  the  towel  covering  the  patient,  is  a 


438 


PREPARATION  AND  FILLING  OF  ROOT  CANALS 


clean  and  convenient  means  with  which  to  remove  such  debris  and  adds 
to  the  neatness  of  the  operation.  A  pair  of  small  scissors  is  necessary 
to  cut  pellets  or  points  to  satisfactory  size. 

Burs  and  Broaches. — There  is  a  great  variety  of  burs  and  broaches 
which  may  be  used  to  advantage  and  different  operators  might  vary  in 
their  selection.  The  spear  drill  for  straight  or  contra  angle  hand-piece 
for  cutting  enamel;  the  cylinder  or  fissure  bur  No.  59  and  the  large 


Fig.  376. — Short  handle  barbed  broaches. 

round  bur  No.  7  are  all  that  seem  necessary.  The  Gates-Glidden  burs 
are  very  useful  in  opening  the  mouth  of  the  canal  to  facilitate  entering 
the  canal  with  the  broach. 

Broaches  should  be  selected  in  graded  sizes  from  the  XXX  (triple  X) 
fine  to  the  fine  in  both  smooth  and  barbed  broaches.  Short  handled 
broaches  (Fig.  376)  are  superior  to  long  ones  as  the  sense  of  touch  is 
lessened  in  proportion  to  the  distance  from  the  working  point.  Metal 
broach  handles  should  be  used  because  of  convenience  of  sterilization 


12     3     4     5 
XIP  XP    F     M     C 
Style  B 


Fig.  377. — Root  canal  files. 


and  in  order  to  economize  the  operator's  time  it  is  well  to  have  one  for 
each  size  of  broach  to  be  used.  The  handles  should  be  marked  to 
prevent  loss  of  time  in  looking  for  the  proper  size.  The  root  canal  file 
(Fig.  377)  is  an  indispensable  instrument  for  enlarging  canals  and 
should  be  used  in  the  various  graded  sizes  from  extra  fine  to  coarse. 

Root  Canal  Pluggers. — The  pluggers   (Fig.  378)  for  packing  the 
gutta-percha  into  the  canal  should  be  slender  and  long  with  sufficient 


EQUIPMENT  FOR  ROOT-CANAL  OPERATIONS 


439 


temper  to  stand  considerable  pressure.  Untempered  pluggers  are  of 
little  use  in  packing.  The  Kerr  Nos.  1-3-5  or  the  S.  S.  White  Nos. 
34-36-39  answer  the  requirements  and  are  satisfactory  and  sufficient 
for  usual  cases. 


Fig.  378. — Root  canal  pluggers. 

Filling  Material. — As  a  temporary  sealing  for  the  tooth  between 
appointments,  base  plate  gutta-percha  has  many  advantages.  It  is 
easy  to  remove  at  the  next  sitting  and  if  properly  manipulated  will 
seal  the  cavity  from  moisture.  However,  care  must  be  used  to  prevent 
pressure  upon  the  dressing  or  any  contents  of  the  canal  which  might 
be  injurious  to  the  periapical  tissue.  Gutta-percha  unless  carefully 
used  will  cause  the  fracture  of  the  crown  of  the  tooth  weakened  by  the 
extensive  drilling  necessary  to  thoroughly  uncover  the  canals.    The 


440  PREPARATION  AND  FILLING  OF  ROOT  CANALS 

most  satisfactory  method  of  sealing  is  gutta-percha  beneath  covered 
well  with  temporary  cement.  Soft  temporary  stopping  should  not  be 
used  for  root-canal  operations. 

Requirements  of  a  satisfactory  root-canal  filling  are  as  follows: 

It  should  be  plastic  so  as  to  be  easily  manipulated  and  carried  into 
all  parts  of  the  canal. 

It  should  not  be  irritating  to  the  periapical  tissue. 

It  should  not  absorb  moisture. 

It  should  be  a  non-conductor  of  thermal  change. 

It  should  not  be  soluble  in  the  fluids  of  the  body. 

It  should  not  shrink  or  change  form  after  insertion. 

It  should  be  opaque  to  the  Roentgen  ray. 

Up  to  the  present  time  gutta-percha  comes  the  nearest  to  meeting 
the  requirements  of  a  successful  root-canal  filling  material.  It  can  be 
made  plastic  by  dissolving  in  chloroform  or  by  softeiiing  with  heat  so 
that  it  can  be  forced  and  packed  into  all  parts  of  the  root  canal.     The 


Fig.   379. — Gutta-percha  cones. 

addition  of  a  few  grains  of  resin  or  some  antiseptic  drug  to  the  chloro- 
form before  adding  the  gutta-percha  is  recommended  by  some  operators, 
but  the  advantages  claimed  for  such  drugs  seem  to  be  of  little  value 
and  often  they  increase  the  difficulties  of  root-canal  filling.  The  great 
problem  of  root-canal  filling  is  the  removal  of  the  organic  matter  from 
the  canal  and  wherever  that  may  be  removed  gutta-percha  can  be  placed 
to  mechanically  fill  the  space.  If  organic  matter  is  left  in  the  canal  it 
will  decompose  and  the  presence  of  any  drug  is  of  little  value  to  counter- 
act the  products  of  such  decomposition.  The  ultimate  purpose  of 
filling  root  canals  is  to  completely  fill  them  and  to  maintain  a  healthy 
periapical  tissue.  This  tissue  is  subject  to  injury  by  mechanical  irri- 
tation, by  chemical  action  of  drugs  or  by  bacterial  action  when  invaded 
by  virulent  organisms  which  cause  a  destructive  inflammation  followed 
by  suppuration.  The  filling  material  should  be  selected  with  the  con- 
sideration of  the  efi^ect  it  might  have  upon  the  periapical  tissue  should 
it  escape  through  the  apical  foramen.     The  complete  filling  of  the 


EQUIPMENT  FOR  ROOT-CANAL  OPERATIONS 


441 


canal  is  of  great  iiii])()rtance  and  this  is  a  very  difHciilt  tliiiii;"  to  accoiu- 
plish  without  the  escape  of  some  of  the  material  through  the  foramen. 
Gutta-percha  answers  the  requirements  quite  well.  The  tissue  will 
accommodate  itself  to  it  although  a  mechanical  injury  is  produced 
where  it  passes  beyond  the  apical  foramen.  It  does  not  absorb  mois- 
ture nor  is  it  soluble  in  the  tissue  fluids.  It  will  not  shrink  away  from 
the  walls  of  the  canal  unless  some  other  substance  is  added  which  will 
dissolve  or  evaporate.  Solutions  of  gutta-percha  will  shrink  but  short 
pieces  of  gutta-percha  (Figs.  374  and  379)  softened  and  packed  under 
pressure  into  a  dense  mass  will  not  shrink  and  the  filling  will  be  imper- 
vious to  moisture  if  it  seals  the  canal  at  each  end. 


Fig.  380.— Operating  tray.  Aseptic  tray  from  root  canal  instrument  cabinet  con- 
taining complete  equipment  of  instruments  and  materials  used  in  the  operation.  Always 
ready  to  use  if  sterilized  before  replacing  in  cabinet. 


The  Operating  Tray. — The  operating  tray  (Fig.  380)  is  simply  a 
sterile  tray  or  perhaps  a  shelf  removed  from  the  root  canal  instrument 
cabinet  with  sufficient  room  upon  it  to  hold  all  the  instruments  and 
materials  necessary  for  the  operation.  There  are  two  distinct  advan- 
tages in  this  plan.  First,  cleanliness  and  second,  conxenience.  If  the 
shelf  or  tray  is  prepared  after  each  operation  before  replacing  it  in  the 
cabinet  it  is  in  readiness  when  needed  with  every  instrument  sterilized 
and  all  sterile  material  in  place  upon  it.  This  procedure  encourages 
carefulness  and  cleanliness  in  the  operator  and  assistant  and  gives  the 
patient  a  feeling  of  confidence  in  the  cleanliness  of  the  operator  and  his 
work. 

Upon  the  tray  should  be  the  aseptic  medicament  tray  and  several 
small  porcelain  minim  trays  for  broaches  of  every  size  and  style  needed 
for  the  operation,  sterilized  cotton  pellets  and  absorbent  points,  metal 


442  PREPARATION  AND  FILLING  OF  ROOT  CANALS 

broach  handles  and  root  canal  pluggers,  an  acid  loop  and  a  pair  of 
scissors  and  any  other  instruments  or  materials  needed  in  the  operation 

(Fig.  380). 

ASEPSIS  IN  ROOT-CANAL  OPERATIONS. 

Asepsis  in  root-canal  operations  is  as  important  as  it  is  in  any  surgical 
operation.  Doubtless,  a  large  percentage  of  the  infected  conditions 
found  in  the  periapical  tissue  about  the  roots  of  teeth  originated  in 
infection  introduced  dutinjg  the  operation  of  filling  the  root.  At  the 
present  time  there  is  no  way  to  differentiate  between  the  various 
causes  of  the  infections  found  in  the  periapical  tissue  about  the 
roots  of  pulpless  teeth.  It  is  evident,  however,  that  in  a  very  large 
percentage  of  all  cases  showing  absorbed  bone  areas  about  the  root 
apices  the  root  is  not  well  filled.  A  careful  survey  of  a  large 
number  of  roentgenograms  of  pulpless  teeth  and  an  accurate 
record  of  the  condition  found  show  substantial  clinical  evidence  in 
favor  of  the  right  kind  of  root-canal  filling.  The  report  of  such  a 
survey  by  Dr.  Arthur  D.  Black,^  covering  roentgenograms  of  1500 
root-canal  fillings,  shows  an  interesting  record.  Dr.  Black  classified 
the  fillings  according  to  large  and  small  canals  and  good  and  poor 
fillings.  The  roots  with  large  or  small  canals  showing  mechanically 
good  fillings  had  an  evidence  of  periapical  disturbances  in  only  about 
10  per  cent,  of  them  while  the  large  or  small  canals  showing  poor  fillings 
gave  evidence  of  periapical  disturbance  in  about  65  per  cent,  of  them. 
This  tabulation  was  made  in  1918,  and  there  is  no  doubt  that  a  very 
large  percentage  of  the  operations  was  completed  before  the  campaign 
for  greater  asepsis  in  root-canal  operations  had  been  generally  effective. 
It  is  safe  to  assume  that  with  the  aseptic  precautions  that  are  being 
used  in  the  operations  of  today  a  much  better  showing  will  be  made  in 
a  similar  survey  a  few  years  hence.  Root-canal  fillings  which  the 
roentgenogram  shows  to  be  mechanically  perfect  usually  have  a  healthy 
periapical  tissue  so  with  the  proper  methods  of  asepsis  in  these  opera- 
tions of  today  there  should  be  a  decided  improvement  in  the  future 
record  of  results. 

The  Instruments  and  Materials. — Under  the  heading  of  Sterilizers, 
several  methods  of  sterilization  of  root-canal  instruments  and  materials 
were  mentioned.  The  all-important  point  is  that  adequate  steriliza- 
tion must  be  used.  It  is  not  difficult  to  find  suitable  equipment  for  this 
but  it  is  somewhat  difficult  to  work  out  a  routine  of  practice  that  is  practi- 
cable and  efficient.  When  constant  use  is  made  of  different  instruments, 
all  very  small  and  hard  to  handle,  the  routine  should  be  as  simple  as  is 

Journal  American  Medical  Association,  October,  1918. 


CLEANING  AND  ENLARGING  THE  CANAL  443 

consistent  with  thoroughness  so  that  adequate  sterilization  may  never  be 
neglected  by  either  assistant  or  operator. 

The  cabinet  containing  the  root  canal  unit  constantly  subjected  to 
formaldehyde  will  maintain  sterilization  and  keep  instruments  and 
materials  previously  sterilized  ready  for  immediate  use.  They  may  be 
sterilized  just  previous  to  the  operation  if  desired.  There  will  not 
be  the  danger  of  neglecting  sterilization,  however,  when  the  cabinet 
contains  the  instruments  and  materials  always  in  readiness  for  use. 
Here  again  the  time-saviilg  method  of  having  a  removable  cabinet 
shelf  to  use  as  an  operating  tray  (Fig.  380)  with  all  materials  and 
instruments  arranged  for  the  operation  is  a  decided  advantage. 

The  operation  upon  the  root  canal  may  now  be  begun  in  an  aseptic 
manner.  To  maintain  asepsis  during  the  operation  the  aseptic  medica- 
ment tray  (Fig.  370)  containing  phenol  and  alcohol  should  be  before 
the  operator  constantly  to  dip  the  broach  in  each  time  before  inserting 
it  into  the  canal.    This  should  become  a  matter  of  unconscious  habit. 

Preparing  the  Field  of  Operation. — It  is  needless  to  say  that  the 
rubber  dam  must  be  used  in  all  cases  of  root-canal  operatioQS.  When 
the  tooth  is  badly  broken  down  it  becomes  necessary  to  cement  a  thin 
copper  band  around  the  tooth  to  support  the  clamp  to  hold  the  rubber 
in  place.  If  the  band  be  properly  fitted  and  cemented  to  place  without 
interference  with  the  occlusion  it  may  be  left  upon  the  tooth  until  the 
root  has  been  filled.  There  are  special  clamps  for  roots  previously 
prepared  for  dowel  crowns  which  will  crowd  the  gum  back  and  grip  the 
end  of  the  root  in  almost  all  cases,  thus  saving  the  time  required  to  fit 
a  copper  band.  The  canal  should  never  be  open  without  the  rubber 
in  place.  The  rubber  isolates  the  field  of  operation  which  is  absolutely 
necessary  to  perform  an  aseptic  operation.  Just  before  adjusting  the 
rubber  the  gums  and  teeth  should  be  sprayed  with  an  antiseptic  wash 
and  tincture  of  iodin  painted  on  the  gum  and  teeth  adjacent  to  the 
tooth  to  be  operated  upon.  When  the  rubber  is  in  place  the  surface 
of  the  teeth  included  within  the  field  should  be  again  washed  with 
tincture  of  iodin. 

CLEANING  AND  ENLARGING  THE  CANAL. 

1.  Gaining  Access  to  the  Pulp  Chamber. — ^The  crown  of  the  tooth 
should  always  be  cut  away  sufficiently  to  expose  the  entire  pulp 
chamber  to  view  and  show  the  openings  of  the  canals.  It  is  not  possible 
to  successfully  manipulate  broaches  around  curves  and  angles,  there- 
fore as  many  as  possible  of  such  obstructions  should  be  eliminated  by 
cutting  away  the  enamel  and  dentin  covering  the  pulp  chamber.  It  is 
far  better  to  sacrifice  a  little  tooth  structure  which  obstructs  root-canal 


444  PREPARATION  AND  FILLING  OF  ROOT  CANALS 

operations  than  to  work  at  a  great  disadvantage  and  perhaps  fail  to 
thoroughly  clean  and  fill  the  canal. 

Incisors  and  Cuspids. — Incisors  and  cuspids  can  best  be  treated 
through  a  small  opening  near  the  center  of  their  lingual  surfaces. 
However,  when  the  tooth  presents  with  a  cavity  on  the  mesial  or  distal 
surface  through  which  access  to  the  canal  may  be  obtained  with  very 
little  further  cutting  of  the  enamel  it  is  better  to  make  the  entrance 
through  the  cavity.  When  entering  on  the  proximate  surface  the 
opening  of  the  canal  should  be  cut  well  over  toward  the  cavity  to  enable 
easy  entrance  of  the  broach  into  the  canal.  Both  mesial  and  distal 
horns  of  the  pulp  chamber  must  be  carefully  opened  and  cleaned  to 
prevent  subsequent  discoloration  of  the  tooth. 

Bicuspids  and  Molars. — In  exposing  the  pulp  chamber  of  a  bicuspid 
or  molar  the  tooth  structure  should  be  cut  away  according  to  the 
requirements  of  each  case.  The  occlusal  opening  on  a  bicuspid  should 
be  extended  buccally  and  lingually  sufficiently  to  enable  the  operator 
to  see  the  mouth  of  each  canal.  The  entire  roof  of  the  pulp  chamber 
should  be  cut  away  and  the  mesial  wall  beveled  to  facilitate  access 
with  the  instruments.  The  molar  crown  should  be  cut  both  in  a  bucco- 
lingual  and  a  mesio-distal  direction  according  to  the  shape  of  the  pulp 
chamber  and  the  location  of  the  canal  openings.  The  upper  and  lower 
first  molars  require  considerable  cutting  toward  the  mesio-buccal  angle, 
for  usually  the  mesio-buccal  canal  is  located  directly  under  the  apex 
of  the  mesio-buccal  cusp.  The  entire  roof  of  the  pulp  chamber  should 
be  cut  away  and  frequently  the  wall  on  the  buccal  needs  cutting  back 
because  the  canal  lies  so  close  in  the  angle  of  the  pulp  chamber.  If 
the  tooth  presents  with  a  disto-occlusal  cavity  it  is  best  to  seal  it  with 
cement  and  open  directly  on  the  occlusal  surface  cutting  well  to  the 
mesio-marginal  ridge.  Should  the  tooth  contain  a  good  filling  on 
the  mesial  surface  extending  on  the  occlusal  surface  it  is  better  to 
remove  it  and  enter  the  pulp  chamber  with  convenience  than  to  leave 
it  to  become  an  obstruction  later  and  thereby  interfere  with  the  success 
of  the  operation.  Each  tooth  requires  a  little  different  cutting,  for 
there  is  a  slight  variation  in  the  shape  of  the  pulp  chambers  and 
location  of  the  canals  of  each.  There  is  a  marked  variation  in  the  first 
and  second  upper  molars.  However,  the  location  of  the  mesio-buccal 
canal  is  usually  directly  beneath  the  apex  of  the  mesio-buccal  cusp. 
The  opening  of  the  canals  in  the  floor  of  the  pulp  chamber  are  usually 
located  so  that  if  lines  should  be  drawn  connecting  them  they  would 
form  the  sides  of  a  triangle  (Fig.  381). 

The  opening  of  the  canals  should  not  be  disturbed  until  the  pulp 
chamber  is  entirely  opened  so  that  all  cuttings  may  be  blown  away 
without  allowing  them  to  enter  the  canals  to  clog  them  up.    Often  it  is 


CLEANING  AND  ENLARGING  THE  CANAL 


445 


necessary  to  bevel  the  mesial  wall  toward  the  mesio-marginal  ridge  and 
cut  away  part  of  the  buccal  and  lingual  walls  to  bring  the  opening  of 
the  canals  into  view. 


B 


c 


D 


Fig.  381. — The  molar  triangle.  Imaginary  lines  drawn  between  canal  openings  in 
pulp  chamber.  Drawings  to  illustrate  location  of  canals  in  different  forms  of  teeth. 
A,  B,  C,  upper  molars;  D,  lower  molar. 

2.  Gaining  Access  to  the  Apical  Foramen. — The  object  of  filling 
root  canals  is  to  seal  the  apical  foramen  after  the  organic  matter  of  the 
pulp  tissue  has  been  removed.  This  objective  can  only  be  attained 
when  there  is  sufficient  access  to  the  foramen  to  enable  the  operator  to 
cleanse  the  canal  thoroughly  and  pack  gutta-percha  into  the  space. 
The  large  canals  seldom  give  much  trouble  but  the  small  canals  like 
the  mesial  canals  of  lower  molars  and  the  buccal  canals  of  upper  molars 
and  the  upper  first  bicuspid  canals  are  difficult  to  enlarge  and  cleanse 
and  when  the  roots  are  curved  or  there  is  secondary  dentin  present  to 
obstruct  the  canal  the  difficulty  is  greatly  increased. 


A  B 

Fig.  382. — Gaining  access  to  the  apical  foramen.  A,  Drawing  to  illustrate  curved 
mesial  root  of  lower  molar.  B,  Drawing  to  illustrate  straightening  the  canal.  The 
obstructing  dentin  should  be  removed  to  allow  a  straight  instrument  to  pass  as  far  as 
possible,  leaving  only  one  curve  to  travel.  Obstructing  dentin  at  (a)  should  be  carefully 
filed  and  cut  away  without  making  a  ledge  in  the  dentin. 

The  process  of  cleansing  and  enlarging  the  canal  also  straightens 
it  and  the  more  nearly  straight  it  becomes  the  better  access  is  obtained. 
A  careful  study  should  be  made  of  the  roentgenogram  of  the  tooth 
before  entering  the  canal  and  the  obstructing  dentin  should  be  cut 
away  as  much  as  possible  to  allow  more  direct  entrance  into  the  canal 
(Fig.  382).  When  the  finest  broach  will  pass  to  the  foramen  of  the 
root,  and  it  usually  will  if  the  attempt  is  made  before  any  other  instru- 


446  PREPARATION  AND  FILLING  OF  ROOT  CANALS 

merit  has  been  inserted  into  the  canal,  the  process  of  cleansing  and 
enlarging  should  be  completed  successfully  and  the  canal  filled  perfectly. 
There  are  many  difficulties  to  encounter  during  the  process  of  enlarge- 
ment, such  as  packing  debris  into  the  apical  third  of  the  canal,  making 
a  ledge  on  the  side  when  the  broach  fails  to  follow  a  curve  in  the  canal, 
or  losing  the  tip  of  a  broach  on  a  curve;  anyone  of  these  three  mis- 
fortunes makes  the  foramen  inaccessible  and  a  complete  canal  filling 
impossible.  A  brief  consideration  of  these  difficulties  follows:  to 
remove  the  debris  from  a  canal  does  not  seem  to  be  a  serious  problem 
and  is  not  if  the  broach  used  for  cutting  is  frequently  removed  and  the 
debris  cleaned  off.  The  files  are  very  useful  for  enlarging  but  they  do 
not  remove  the  debris  very  well,  so  it  becomes  necessary  to  follow  them 
with  a  very  fine  (XXX)  barbed  broach  to  rake  out  the  filings  and 
shreds  of  organic  materials.  This  is  attended  with  considerable  danger 
of  losing  a  point  of  the  broach  for  the  canal  is  very  small  and  perhaps 
curved  and  the  slightest  binding  of  the  barbs  upon  the  side  of  the  canal 
may  cause  a  piece  of  the  broach  to  break  away  and  plug  the  canal  at 
that  point.  Another  difficulty,  that  of  making  a  ledge  or  losing  the 
canal,  is  caused  by  using  too  large  a  broach  which  will  not  follow  the 
curve  in  the  root  and  consequently  bores  a  depression  in  the  dentin 
at  the  curve  instead  of  following  the  canal  around  the  curve.  When  a 
curve  is  encountered  the  walls  must  be  carefully  filed  away  with  small 
files  to  straighten  the  canal  to  give  access  to  the  foramen  (Fig,  382). 
The  opening  of  the  canal  in  the  pulp  chamber  may  be  enlarged  with  a 
small  Gates-Glidden  drill  to  facilitate  locating  it,  but  the  point  of  the 
instrument  must  always  be  kept  in  the  canal  to  prevent  making  a  false 
pocket  which  would  be  a  great  handicap  in  the  following  operation. 
The  curves  should  be  carefully  filed  away  and  the  debris  removed,  using 
the  finest  broaches  until  the  foramen  is  reached.  A  broach  should 
never  be  used  which  is  too  large  to  pass  to  the  foramen  ^ach  time  until 
the  canal  has  been  enlarged  and  straightened  to  remove  the  danger  of 
losing  the  canal  and  making  a  false  pocket  in  the  dentin. 

3.  Checking  up  by  Roentgenogram.^ — A  roentgenogram  should  be 
made  of  every  tooth  requiring  treatment  before  beginning  the  operation 
in  the  pulp  chamber  or  canals.  Sometimes  the  roentgenogram  will 
show  a  condition  which  makes  canal  operations  inadvisable  because  of 
crooked  roots  or  obstructed  canals  and  very  frequently  the  periapical 
tissue  will  be  found  so  badly  diseased  that  the  retention  of  the  tooth 
might  be  a  menace  to  the  general  health  of  the  patient. 

When  the  operation  is  under  way  and  there  is  some  difficulty  encoun- 
tered or  some  doubt  as  to  the  progress  of  the  operation  it  is  well  to  insert 
a  wire  in  the  canal  allowing  one  end  to  be  flush  with  the  occlusal  surface 
of  the  tooth  (Fig.  383)  and,  after  sealing  up  the  cavity  with  temporary 


FILLING  THE  CANAL  447 

stopping,  a  roentgenogram  should  be  taken  to  check  up  the  work  to 
this  point.  This  is  a  great  aid  to  the  operator  and  requires  but  very 
little  time  and  inconvenience  especially  where  the  operator  makes  his 
own  roentgenograms. 

When  the  canal  is  ready  to  fill  a  small  stiff  root  canal  plugger  like 
Kerr  No.  1  or  the  S.  S.  White  No.  34  should  pass  to  within  three  milli- 
meters of  the  apical  foramen  (Fig.  384).  The  space  between  the  end 
of  the  plugger  and  the  apical  foramen  is  the  most  important  portion  of 
the  canal  and  the  future  health  of  the  periapical  tissue  is  largely  depen- 
dent upon  the  successful  filling  of  this  part  of  the  canal,  especially  of  the 
larger  canals. 

4.  Measuring  Length  of  the  Canal  and  the  Diameter  of  the  Foramen. 
— The  length  of  the  canal  is  determined  by  the  length  of  the  measm-e 
wire  inserted  before  taking  the  roentgenogram.  The  roentgenogram 
shows  the  relative  length  of  the  wire  in  comparison  to  the  root.  The 
wire  should  be  cut  so  that  one  end  is  flush  with  the  occlusal  surface 
when  it  is  in  the  canal.  Frequently  the  roentgenogram  gives  an  eloa- 
gated  or  shortened  picture  of  the  tooth  and  the  inaccuracy  of  the 
picture  can  usually  be  estimated  and  added  to,  or  deducted  from,  one 
end  because  the  other  end  of  the  wire  is  even  with  a  definite  surface 
landmark  from  which  measurement  can  be  calculated. 

The  diameter  of  the  apical  foramen  may  be  calculated  by  the  size 
of  the  plugger  which  will  pass  to  it,  or  by  an  absorbent  paper  point 
with  the  small  end  clipped  off  until  it  will  just  reach  the  foramen  but 
not  pass  through. 

Now  with  the  measure  wire  corrected  to  the  proper  length  and  with 
a  fairly  close  measure  of  the  diameter  of  the  foramen  the  filling  of  the 
canal  may  be  started. 

FILLING  THE  CANAL. 

When  the  canal  has  been  thoroughly  cleansed  and  enlarged  to  ac- 
commodate instruments  suited  for  packing  gutta-percha  to  the  apical 
foramen  it  is  ready  for  filling  unless  some  complication  is  encountered. 
The  canal  must  be  dry  and  aseptic  and  the  apical  tissue  in  a  healthy 
condition  before  a  successful  root-canal  filling  can  be  inserted. 

The  measure  wire  and  the  absorbent  point  used  to  ascertain  the 
length  of  the  canal  and  the  diameter  of  the  foramen  should  be  upon  the 
tray  before  the  operator.  The  plugger  which  will  pass  to  the  apical 
third  of  the  canal  should  be  marked  or  bent  so  as  to  show  when  it  is 
within  three  millimeters  of  the  apical  foramen  when  placed  in  the  canal. 
When  it  is  in  the  canal  as  far  as  the  mark,  the  operator  has  only  to 
estimate  the  small  space  between  the  end  of  the  plugger  and  the  fora- 


448 


PREPARATION  AND  FILLING  OF  ROOT  CANALS 


men  (Figs.  384  and  385).  This  is  the  most  important  part  of  the  entire 
fining  and  the  more  successful  the  operator  is  in  thoroughly  sealing 
the  apical  foramen  without  injury  to  the  periapical  tissue  the  nearer 
will  the  result  approach  a  perfect  operation.     The  gutta-percha  cone 


Fig.  383  Fig.  384  Fig.  385 

Fig.   383. — Measuring  length  of  canal.     Wires  flush  with  occlusal  landmark. 
Fig.   384. — Plugger  No.  1  inserted  in  buccal  canals.     The  bend  in  shank  indicates  the 
distance  necessary  to  insert. 

Fig.   385. — Plugger  to  reach  within  3  mm.  of  foramen.     The  space  between  the  plug- 
ger and  the  foramen  is  the  most  important  of  the  entire  space  to  be  filled. 

suitable  for  the  canal  should  be  selected  and  cut  in  pieces  of  about 
three  millimeters  in  length.  It  is  necessary  to  use  many  more  of  the 
small  ends  of  the  gutta-percha  cone  than  the  other  pieces,  therefore  it 
saves  time  to  have  a  dish  with  compartments  to  contain  cut  cones  of 


Fig.  386  Fig.  387  Fig.  388 

Fig.  386. — Plugger  No.  1  carrying  first  piece  of  gutta-percha  cone  selected  to  seal  the 
apical  foramen.  Plugger  is  inserted  to  bend  in  shank  and  gutta-percha  should  just  reach 
the  apical  foramen  and  be  large  enough  to  prevent  passing  through  the  foramen. 

Fig.  387. — First  piece  of  gutta-percha  cone  packed  in  place  sealing  the  foramen.  If 
measurement  is  accurate  there  should  be  no  excess  filling.  The  second  piece  is  packed 
against  this  with  considerable  pressure  followed  with  piece  after  piece,  until  the  canal  is 
full. 

Fig.  388. — Canals  filled.  Short  pieces  added  one  by  one  in  same  manner,  packing 
each  thoroughly  until  the  roots  are  all  filled. 


different  sizes  (Fig.  374).  The  larger  sizes,  Nos.  3  and  6  (Fig.  379) 
furnish  the  best  first  points  to  be  used  in  plugging  the  foramen  while 
the  smaller  sizes  8,  10  and  12,  furnish  better  pieces  for  filling  the  middle 
third  of  the  canal. 


FILLING  THE  CANAL 


449 


The  point  piece  of  gutta-percha  suitable  for  plugging  the  apical 
foramen  should  be  selected  and  placed  upon  the  end  of  the  root-canal 
plugger.  The  plugger  should  be  heated  slightly  in  the  flame  so  that 
the  gutta-percha  will  adhere  to  it  when  pressed  upon  the  larger  end  of 
the  piece. 

The  canal  should  be  dry  before  filling.  It  should  then  be  slightly 
moistened  with  eucalyptol  throughout  its  entire  length.  A  very  small 
amount  of  chlorapercha  may  be  carried  into  the  canal  to  adhere  to  the 
walls  and  to  help  in  filling  all  the  opea  space  in  the  apical  portion  of 


'^  Fig.  389. — Wires  measuring  length  of 
lower  molar  canals.     Tooth  in  position. 


Fig.  390. — Root-canal  plugger  inserted 
in  distal  canal.  Bend  at  occlusal  surface 
marks  the  distance  the  plugger  should  be 
inserted  to  reach  within  1  mm.  of  foramen. 


Fig.  391. — Canals  filled.    Distal  canal  divided  into  two  branches. 


the  canals.  The  less  clilorayercha  used  the  more  accurate  should  he  the 
result  since  it  is  impossible  to  prevent  overfilling  when  much  chlora- 
percha is  used.  The  large  carals  require  less  chlorapercha  than  the 
small  ones  since  the  gutta-percha  points  can  be  packed  clear  to 
the  apical  foramen  of  large  canals  with  little  difficulty.  Now  the 
plugger  carrying  the  selected  piece  of  gutta-percha  cone  should  be 
inserted  into  the  canal  and  forced  slowly  down  till  the  mark  or  bend 
indicates  that  it  has  gone  to  place  (Fig.  386).  If  the  measurement  has 
been  accurate  this  will  seal  the  foramen  since  the  gutta-percha  on  the 
end  of  the  plugger  should  just  reach  the  foramen  when  the  plugger  is 
29 


450  PREPARATION  AND  FILLING  OF  ROOT  CANALS 


Fig.  392 


Fig.  393 


Fig.  394 


Fig.  395 


Fig.  396 


Fig.  397 


Fig.  398  Fig.  399 

Figs.  392  to  399. — Root-canal  fillings.  Figs.  392  and  393  show  branches  of  the  main 
canal  have  also  been  filled. 


RECORDING  451 

inserted  as  far  as  the  mark  (Fig.  387) .  This  should  be  followed  by 
selected  pieces  of  cut  cones  softening  each  slightly  by  warming  and 
packing  them  into  the  canal  until  it  is  filled.  After  sealing  with  a  hot 
burnisher  the  filling  is  complete. 

A  roentgenogram  of  the  tooth  should  be  made  to  prove  the  filling 
(Fig.  388)  and  unless  it  is  satisfactory  it  should  be  removed  and  the 
canal  refilled. 

TO  REMOVE  ROOT  FILLINGS. 

A  gutta-percha  root-canal  filling  can  be  removed  easily  by  heating  a 
small  root-canal  plugger  or  explorer  and  softening  it  as  much  as  possi- 
ble, then  by  flooding  the  pulp  chamber  with  chloroform  or  xylol.  The 
last  named  drug  will  soften  gutta-percha  very  rapidly  but  care  must  be 
used  to  prevent  it  passing  through  the  foramen,  as  it  is  quite  irritating. 
Xylol  should  never  be  sealed  in  the  tooth.  Chloroform  or  eucalyptol 
may  be  sealed  within  the  pulp  chamber  for  twenty-four  hours  to  a  good 
advantage  in  some  cases.  Root-canal  fillings  of  cement  are  extremely 
difficult  to  remove  as  this  material  is  so  hard  that  the  instrument  will 
not  follow  it.  Hydrochloric  acid  will  sometimes  assist  but  it  must 
be  used  with  great  care  and  must  be  neutralized  with  a  solution  of 
sodium  carbonate.  The  difficulty  of  removal  is  one  of  the  chief 
objections  to  the  use  of  cement  as  a  filling  material  for  root  canals. 

RECORDING. 

A  complete  record  should  be  kept  of  every  tooth  having  root-canal 
operations,  The  record  should  begin  with  the  condition  of  the  pulp 
and  periapical  tissue  before  the  operations  are  begun.  If  we  had  a 
record  today  of  the  condition  of  the  periapical  tissue  surrounding  the 
teeth  with  root-canal  fillings  before  they  were  inserted  it  would  be 
possible  to  differentiate  between  some  of  the  causes  of  the  absorptions 
of  periapical  tissue.  As  we  have  not  such  a  record  we  can  only  class 
all  absorptions  together.  A  detailed  daily  record  of  the  method  of 
pulp  removal,  the  drugs  used  in  the  treatment  and  the  method  of  seal- 
ing the  treatment  in  the  tooth  should  be  kept.  A  very  useful  form  has 
been  suggested  by  Dr.  A.  D.  Black  of  Chicago  whereby  such  a  record 
may  be  kept  with  very  little  inconvenience  and  loss  of  time  (Fig.  400) . 
If  we  record  the  condition  of  the  pulp  and  periapical  tissue  of  each 
tooth  before  the  operation  is  begun  and  keep  a  complete  roentgeno- 
graphic  record  of  the  periapical  tissue  from  the  time  of  treatment,  it 
will  be  of  great  value  in  the  history  of  pulpless  teeth  relating  to  the 
development  of  future  conditions.  It  is  evident  that  every  drug  used 
in  the  treatment  of  pulpless  teeth  has  some  effect  upon  the  condition 


452  PREPARATION  AND   FILLING  OF  ROOT  CANALS 

DENTAL  PULP  CASE  HISTORY 


Patient's 
Name 


Age 


Patient's 

NtTMBEK 


Address 


Tooth. 

Diagnosis. 

Color. 

Removal. 

Treat- 
ment. 

Seal- 
ing. 

Root  filling. 

c 

Subsequent 
radiograph. 

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Fig.  400. — Dental  pulp  case  history.  Directions.  This  chart  is  printed  on  an 
envelop,  the  illustration  being  actual  size.  The  history  is  to  be  made  out  as  the  case 
progresses;  the  radiographs  of  the  case  to  be  kept  in  the  envelop.  If  the  pulp  is  dead 
or  if  the  root  has  been  pre^aously  filled  the  patient  is  required  to  have  a  radiograph  made 
before  treatment  is  begun. 

1.  Enter  patient's  name,  age  and  address. 

2.  Indicate  tooth  by  number  or  letter. 

3.  Diagnosis:  (a)  If  the  pulp  is  %'ital  and  normal  and  is  to  be  removed  because  a  croTvn 
is  to  be  made,  or  if  it  is  accidentally  exposed  in  cavity  preparation,  mark  X  in  first 
column.  (6)  If  pulp  is  vital  and  is  removed  on  account  of  hj-peremia  which  has  developed 
into  inflammation,  mark  X  in  second  column,  (c)  If  pulp  is  \dtal  and  exposed  bj'  caries 
or  so  nearly  exposed  that  its  removal  is  required,  mark  X  in  third  column,  (d)  If  pulp 
is  dead,  mark  X  in  fourth,  fifth  or  sixth  column,  according  to  the  condition  shown  by 
the  radiograph.  It  ■n'ill  be  considered  a  slight  abscess  if  any  injury  to  the  bone  is  shown 
and  treatment  is  undertaken.  It  will  be  marked  in  column  "  Abs.  Extract"  if  treatment 
is  not  considered  ad\-isable.  (e)  If  there  is  a  previous  root  filling,  mark  X  in  the  last 
column  also  an  X  in  column  four,  five  or  six,  according  to  the  condition  shown  by  the 
radiograph. 

4.  Color  of  tooth:    Mark  X  in  proper  column. 

5.  Removal  of  pulp:  (a)  If  arsenic  is  applied,  enter  date  in  figures  in  proper  column 
as  5,  2,  16.  (b)  If  cocain-pressure  is  used  or  novocain  anesthesia,  infiitration  or  conduc- 
tive, enter  date  in  proper  column,  (c)  Enter  date  the  pulp  is  removed  in  proper  column. 
This  date  is  to  be  entered  if  arsenic  was  applied  or  if  the  tissues  were  anesthetized  or  if 
the  pulp  was  dead. 

6.  Treatment:  Enter  date  of  application  of  medicaments.  If  a  second  treatment  of 
the  same  drug  is  made,  enter  date  on  second  horizontal,  etc.  Doubtless  many  dentists 
would  prefer  to  have  other  drugs  entered  in  these  column  headings. 

7.  Sealing:     Mark  X  in  the  proper  column. 

S.  Root  filling:  (a)  Mark  in  first  column  length  of  tooth  from  occlusal  surface  or 
incisal  edge  in  millimeters,  making  measurement  with  a  fine  smooth  broach  and  using 
a  Boley  gauge.  If  the  crown  is  bioken  off  so  state  at  bottom  edge  of  envelop.  Place 
diagnostic  wire  and  have  radiograph  made,  (h)  Mark  date  in  second  or  third  column  to 
indicate  gutta-percha  alone  or  chloropercha  and  gutta-percha  used  as  root  filling,  (c) 
If  canal  is  inaccessible  to  apex,  indicate  by  fraction  y,  f  or  f,  etc.,  according  to  distance 


RECORDING  453 

of  the  periapical  tissue  so  it  is  of  great  importance  that  such  a  record 
should  be  kept  in  the  tooth  history.  The  method  of  filling  and  the 
material  used  should  be  recorded  and  any  other  remarks  regarding  the 
nature  or  peculiarity  of  the  case,  which  might  have  some  bearing  upon 
future  conditions,  should  be  kept.  Teeth  should  be  saved,  not  all 
diseased  teeth,  but  teeth  that  are  healthy  or  that  can  be  made  healthy 
and  it  is  the  duty  of  the  profession  to  master  this  great  problem  and 
successfully  cleanse  and  fill  root  canals  so  that  they  may  be  retained 
with  safety  to  function  in  mastication  as  nature  intended. 

diagnostic  wire  shows  in  radiograph,  (d)  Have  radiograph  made  of  root  filling.  Mark 
X  indicating  whether  it  is  considered  a  good  or  a  fair  filling.  In  case  it  is  a  poor  filling 
a  new  root  filling  should  be  made,  also  another  radio.graph.  (e)  In  cases  of  teeth  ha\dng 
more  than  one  canal,  use  a  separate  horizontal  line  for  each  canal  and  indicate  each  by 
writing  the  initials,  as  ni-l,  m.-b,  d-h,  dis.,  ling.,  hxc.,  etc. 

9.  Resection:     If  root  is  resected,  enter  date  in  this  column. 

10.  Subsequent  Radiograph:  It  is  the  intention  to  send  for  patients  to  return  in 
about  six  months  and  make  a  check-up  radiograph.  When  this  is  done  the  date  should 
be  entered  in  the  proper  column,  indicating  the  condition  of  the  bone  at  that  time. 
Additional  radiographs  should  be  made  after  several  j-ears. 

11.  Color.  The  color  of  the  tooth  will  be  marked  by  the  date  of  a  subsequent  exami- 
nation.— Dental  Summary,  October,  1919,  xxxix,  749. 


CHAPTER  X. 

PATHOLOGY  AND  TREATMENT  OF  HYPERSENSITIVE 

DENTIN. 

By  HERMANN  PRINZ,  M.D.,  D.D.S. 

Hypersensitive  dentin  may  be  defined  as  a  state  in  which  the 
exposed  dentin  of  a  vital  tooth  is  painfully  responsive  to  mechanical, 
chemical,  thermal  and  electrical  irritation.  The  primary  cause  must 
be  attributed  to  its  exposure  to  an  irritant.  Absence  of  enamel  or 
otherwise  pathologically  exposed  dentin  is  the  iritial  condition  essential 
for  its  causation.  Enamel,  which  protects  the  dentin  of  the  crown, 
may  be  absent  as  a  result  of  incomplete  calcification,  or  may  be  lost  ■ 
through  pathologic  processes — that  is,  caries,  erosion,  abrasion  or 
trauma,  while  the  exposed  dentin  of  the  root  of  a  tooth  is  primarily 
brought  about  by  premature  or  senile  atrophy  of  its  protective  alveolar 
process. 

Pathology. — Before  entering  upon  a  discussion  of  the  pathology  of 
hypersensitive  dentin  the  anatomy  and  physiology  of  normal  dentin 
should  be  recalled  briefly.  Dentin  is  made  up  of  about  72  per  cent, 
inorganic  salts,  about  10  per  cent,  water  and  an  organic  matrix  con- 
stituting the  remaining  percentage.  The  dentin  is  traversed  by  a  very 
large  number  of  tubuli  measuring  about  1^  to  5  ^  in  diameter  aud  radi- 
ating from  the  pulp  cavity,  more  or  less  wave-like,  toward  the  peri- 
phery, where  they  branch  off,  forming  a  deltoid  network.  Roemer  has 
counted  from  25,000  to  30,000  dentinal  tubuli  within  the  area  of  a 
square  millimeter.  The  tubuli  are  filled  with  lymph  and  with  the 
protoplasmic  processes  of  the  odontoblasts,  as  originally  described  by 
Koelliker,  and  they  are  known  as  Tomes's  fibers.  These  fibers  are 
structureless  threads  and  are  continuous  through  the  full  length  of  the 
tubuli  and  their  branches. 

Physiologically  normal  dentin  has  no  sensation;  its  vital  protoplasm 
transfers  tactile  impressions,  thermal  changes  and  chemical  or  electrical 
irritation  to  the  pulp. 

The  so-called  innervation  of  dentin  is  still  a  much  mooted  question. 

Professor  Hopewell-Smith  interprets  its  present  status  as  follows: 

"  It  is  an  interesting  and  important  fact  that  it  has  not  yet  been  proved 

to  the  entire  satisfaction  of  all  observers  that  nerve  fibers  exist  in  the 

(454) 


PATHOLOGY  455 

dentinal  tubes.  Thus  there  is  a  wide  difference  in  men's  views  as  to 
the  innervation  or  non-innervation  of  the  dentin.  One  school  of 
belief,  headed  by  Boll,  Morgenstern,  Roemer,  Dependorf,  Fritzsch 
and  Howard  Mummery  endeavors  to  explain  sensitiveness  to  the 
occurrence  of  peripheral  nerve  fibers  in  the  dentinal  tubuli,  while  the 
other  school  denies  the  existence  of  nerve  fibers  in  this  tissue.  Among 
those  included  in  this  group  are  Retzius,  Koelliker,  Tomes,  Huber, 
Walkhoff,  Gysi  and  Hopewell-Smith.  By  persistent  search  in  teeth 
of  mammals  and  reptiles  no  definite  nervous  system  has  been  dem- 
onstrated, the  nerve  fibers  terminating  in  arborizations  around  the 
odontoblasts  on  the  surface  of  the  dental  pulp. 

Impulses  are  carried  through  the  dentin  to  the  pulp  nia  the  contents 
of  the  dentinal  tubuli,  i.  e.,  dentinal  fibrils,  the  peripheral  processes  of 
the  odontoblasts,  and  lymph.  There  is  an  abundance  of  protoplasm 
in  these  innumerable  channels.  Members  of  the  second  school  of 
thought  are  divided  in  their  views  as  to  the  causes  of  sensation.  The 
hylopathist  ascribes  it  to  abnormal  movements  of  the  molecules  of  the 
dentinal  fibrils  while  the  others  claim  that  demarcation  currents,  con- 
vection and  osmosis  are  responsible  for  pain.  All,  however,  are  agreed 
that  the  cerebro-spinal  nervous  system  has  no  share  in  its  production 
beyond  that  in  the  dental  pulp." 

Personally  the  author  is  in  full  accord  with  the  concepts  of  the 
second  school  of  histologists,  i.  e.,  the  non-innervation  hypothesis  of 
dentin.  From  a  pharmacologic  point  of  view  he  is  able  to  furnish 
sufficient  data  to  substantiate  this  assumption.  Basing  his  own  con- 
ception upon  this  hypothesis,  he  assumes  that  hypersensitive  dentin 
denotes  a  state  in  which  the  contents  of  the  dentinal  tubuli  are  patho- 
logically altered.  This  change  is  brought  about  by  external  physico- 
chemical  influences  which  interfere  with  surface  tension,  absorption  and 
diffusion.     All  three  of  these  processes  are  closely  allied  phenomena. 

According  to  Gibb's  law  all  substances  which  lower  the  surface 
tension  of  a  solvent  become  more  concentrated  in  the  surface  film  than 
in  the  interior.  It  is  a  phenomenon  which  depends  upon  the  increase 
of  attraction  of  the  molecules  in  the  surface  film  for  one  another  and 
puts  the  film  under  pressure.  Thereby  a  hydrostatic  pressure  is 
created  which  materially  increases  the  normal  osmotic  pressure.  As  a 
rule  inorganic  neutral  salts  and  many  sugars  raise  the  surface  tension 
very  slightly,  whereas  acids,  bases  and  most  organic  substances  lower 
the  surface  tension.  The  colloids  concentrated  in  the  surface  film 
become  very  viscous,  finally  forming  a  membrane  insoluble  in  water. 
Colloidal  solutions  readily  absorb  water  and  dissolve  salts  from  the 
surrounding  medium.  The  absorption  of  water  increases  proportion- 
ally with  the  concentration  of  the  salt  solution  to  a  certain  point  and 


456  PATHOLOGY  OF  HYPERSENSITIVE  DENTIN 

thereby  an  increase  in  the  internal  pressure  of  the  colloidal  solution 
is  obtained. 

Surface  tension  is  constantly  trying  to  reduce  itself;  in  a  uniform 
fluid  this  is  impossible,  while  in  a  mixture  consisting  of  two  or  more 
substances  which  in  themselves  possess  different  surface  tension  the 
lighter  fluid  has  a  tendency  to  collect  on  the  surface  of  the  more  tense 
fluid.  Under  the  influence  of  these  different  forces,  dynamic  equi- 
librium is  established  within  a  certain  time.^  These  various  factors 
favor  mechanical  absorption,  reduction  of  surface  tension,  increase  of 
solubility  under  pressure  and  compressibility  of  water. 

Chemical  absorption  is  of  less  interest  in  this  connection.  The  most 
important  factor  which  influences  absorption  is  the  ion  concentration 
of  a  fluid.  The  equilibrium  of  a  phase  relative  to  its  ion  concentration 
is  controlled  by  the  law  of  mass  action. 

The  relative  viscosity  of  a  fluid  plays  a  most  important  role.  If  the 
surface  of  a  solution  absorbs  a  dissolved  substance  the  viscosity  of  its 
surface  may  be  markedly  increased.  As  a  consequence  albumins, 
soaps,  saponins,  dyestuffs,  etc.,  form  a  surface  fllm  which  materially 
interferes  with  the  dift'usibility,  as  compared  to  pure  water,  of 
dissolved  substances. 

When  the  colloidal  contents  of  the  dentinal  tubuli  become  exposed 
to  the  fluids  present  in  the  oral  cavity  their  surface  tension  becomes 
altered  by  absorption  and  diffusion  in  accordance  with  the  above 
enumerated  physico-chemical  processes;  they  become  overdistended 
and  thereby  exert  pressure  upon  the  underlying  odontoblastic  cells. 
The  fluids  in  the  tubuli  cannot  be  compressed  as  water  possesses  no 
elasticity;  it  represents  a  rigid  column  which  transmits  pressure  in  the 
form  of  motion  undiminished  in  all  directions.  Any  additional  pres- 
sure which  is  exerted  upon  the  overdistended  surfaces  is  at  once  trans- 
mitted to  the  nerve  filaments  located  at  the  sm-face  of  the  pulp  (the 
plexus  of  Boll),  that  is,  the  anatomic  threshold  of  sensation. 

Cutting  the  enamel  does  not  produce  painful  sensation.  As  soon  as 
the  dento-enamel  junction  is  reached,  marked  pain  is  usually  exper- 
ienced by  the  patient.  Beneath  the  dento-enamel  junction  are  located 
the  interglobular  spaces  of  Czermak,  which  are  filled  with  semifluid 
protoplasm.  Pressure  and  heat  produced  by  the  revolving  bur  upon  a 
relatively  large  surface  area  of  fluid  in  this  region  are  quickly  trans- 
mitted to  the  pulp,  and  hence  pain  is  felt.  Within  the  area  of  dentin 
which  lies  beyond  this  zone,  sensation  is  lessened  until  the  advancing 
bur  reaches  within  close  proximity  of  the  pulp.  In  carious  dentin, 
excavation  of  the  zones  of  complete  disorganization  and  of  decalcifica- 

1  Decrease  in  surface  tension  is  readily  demonstrated  by  the  following  simple  experi- 
ment: to  100  c.c.  of  absolute  alcohol  contained  in  a  graduated  cylinder,  add  100  c.c. 
of  distilled  water.     After  equilibrium  is  established  the  mixture  measures  only  192  c.c. 


PATHOLOGY  457 

tion  does  not  produce  sensation  because  the  contents  of  the  tubuU  are 
destroyed.  As  soon  as  the  zone  of  turbidity  is  reached,  marked  pain 
is  manifested.  Here  the  contents  of  the  exposed  dentinal  tubuU  are 
subjected  to  intense  irritation  brought  about  by  acidity  and  other 
products  of  bacterial  metabolism.  The  surface  tension  of  the  fluids 
in  the  tubuli  is  altered  markedly,  hence  the  quick  response  to  pressure 
and  thermal  influences.  Below  this  zone  of  turbidity  the  '^  translucent 
zone  of  Tomes"  is  observed  in  chronic  caries.  This  translucency  of 
dentin  is  the  product  of  a  vital  reaction.  The  chronic  irritation  of  the 
odontoblasts  causes  the  pulp  to  respond  promptly  by  depositing 
adventitious  dentin  within  the  lumen  of  the  tubuli,  which  necessarily 
lessens  their  diameter  in  varying  degrees,  or  even  produces  complete 
obliteration.  Hence  a  smaller  surface  of  the  tubular  contents  is 
exposed  to  the  advancing  bur,  and,  consequently,  lessened  sensation  is 
felt.  The  gradual  reduction  of  surface  area  of  the  dentinal  tubuli 
is  a  physiologic  process  in  the  life  cycle  of  a  tooth,  hence  sensitiveness 
diminishes  with  advancing  age. 

IMechanically  abraded  teeth  or  those  subjected  to  the  as  yet  little 
known  process  of  erosion  are  rarely  hypersensitive  in  the  later  stages. 
Abrasion  and  erosion  are  usually  intensely  chronic  processes,  hence 
their  very  slow  progress  offers  to  the  irritated  odontoblasts  sufficient 
time  to  deposit  adventitious  dentin  within  the  tubuli  and  thereby 
protects  the  underlying  pulp  from  further  irritation.  Sections  of 
mechanically  or  chemically  abraded  teeth  containing  living  pulps 
always  show  a  translucent  zone. 

As  stated  above  the  process  of  removal  of  enamel  of  a  sound  tooth 
by  cutting  and  grinding,  if  done  under  proper  precautions  to  avoid 
undue  heat,  is  usually  not  painful.  The  freshly  exposed  dentin  is 
relatively  free  from  sensation.  Within  a  short  lapse  of  time,  however, 
usually  mthin  twenty-four  hours,  this  exposed  dentin  is  extremely 
hj-persensitive.  The  exposure  of  the  contents  of  the  tubuli  to  the 
ffuids  of  the  mouth,  as  explained  above,  changes  the  sm-face  tension 
so  as  to  cause  pronounced  irritation  of  the  odontoblastic  cells. 

Dehydration  of  the  overdistended  tubuli  by  physical  means  relieves 
the  hypertension;  consequently,  such  an  agent  as  warm  air  reduces 
the  sensibility.  Alcohol,  potassium  hydroxid  or  similar  hygroscopic 
chemicals  act  sjiichronically  as  dehydrants  and  caustics.  Self- 
luniting  caustics,  as  silver  nitrate,  perhydrol,  etc.,  superficially  destroy 
the  vitality  of  the  protoplasmic  fibers,  and  they  protect  the  contents 
of  the  tubuli  by  solid  plugs  of  precipitated  albumin.  The  disturbing 
elements  are  thereby  permanently  excluded  from  reaching  the  dentin. 
The  distiu-bed  equilibrium  of  the  tubular  fiuid  readjusts  itself  in  a 
short  time  and,  consequently,  hyperesthesia  is  relieved.     A  substantial 


458       PATHOLOGY  OF  HYPERSENSITIVE  DENTIN 

illustration  of  this  fact  is  furnished  by  protecting  immediately  arti- 
fically  exposed  dentin  with  a  coating  of  silver  nitrate  or  a  temporary 
cap  set  with  gutta-percha  and  not  with  an  irritating  cement.  Such 
dentin  will  exhibit  no  particular  sensation  at  any  time  after  the 
operation. 

Any  general  condition  which  lowers  the  normal  psychic  reaction  of 
a  patient  naturally  also  influences  the  reactivity  of  the  tooth  pulp. 
Therefore,  such  disturbances  as  acute  nasal  catarrh,  influenza,  exanthe- 
matous  fevers,  increased  intradental  blood-pressure,  menstruation, 
anemia,  general  debility  or  certain  neuropathic  conditions,  as  neuras- 
thenia, may  leave  their  imprint  upon  the  pulps  in  the  form  of  congestive 
hyperemia  and,  consequently,  any  irritation  of  the  exposed  dentin  of  a 
tooth  under  these  conditions  is  prone  to  exhibit  indirectly  excessive 
sensibility. 

From  the  above  discussion  of  its  pathology  the  author  concludes 
that  hypersensitive  dentin  designates  a  state  of  irritation  of  the 
odontoblasts  of  a  vital  pulp.  Irritation  is  produced  only  by  external 
agents,  i.  e.,  physico-chemical  processes  induce  changes  in  the  surface 
tension  (hypertension)  of  the  exposed  contents  of  the  tubuli.  The 
increased  reactivity  of  the  disturbed  equilibrium  transmits  any 
additional  physical  or  chemical  impulse  at  once  via  Tomes'  fibers  to  the 
congested  odontoblastic  cells  covering  the  pulp,  which  are  in  direct 
contact  with  the  nerve  fibers  of  the  plexus  of  Boll,  i.  e.,  the  anatomic 
threshold  of  sensation. 

Symptoms  and  Treatment. — The  principal  subjective  symptom  of 
hypersensitive  dentin  consists  of  more  or  less  severe  pain,  which  is 
usually  elucidated  by  marked  temperature  changes,  chemical  irritation 
or  mechanical  interference  of  the  exposed  dentin  surface.  The  pain  is 
not  continuous,  it  merely  lasts  as  long  as  the  irritant  is  present.  The 
patient  may  present  a  carious  or  otherwise  defective  crown  of  a  tooth, 
an  exposure  of  its  root  or,  frequently,  an  incomplete  union  at  the 
periphery  of  the  enamel  and  cementum  at  its  neck.  The  thermal 
test  with  hot,  and  especially  cold,  water  or  pressure  exerted  by  an 
instrument  placed  upon  the  exposed  surface  of  the  dentin  is  very 
pronounced.  Changes  in  the  color  of  the  tooth,  percussion,  palpation 
and  roentgenogram  are  negative.  Hypersensitive  dentin  offers  good 
chances  for  conservative  treatment;  under  proper  management  it 
may  be  eradicated  readily. 

The  rational  principle  of  treatment  should  be  based  on  the  recogni- 
tion of  its  pathologic  cause,  that  is,  hypertension  of  the  contents  of  the 
dentinal  tubuli.  Any  method  or  means  which  favors  the  readjustment 
of  the  altered  colloidal  equilibrium  and  prevents  further  irritation  of 
the  exposed  dentin  surface  is  useful  for  the  purpose. 


SYMPTOMS  AND  TREATMENT  459 

In  general  the  remedies  employed  should  conform  to  the  following 
requirements : 

1 .  The  remedy  must  not  injure  the  organic  or  inorganic  constituents 
of  the  tooth. 

2.  The  remedy  must  not  permanently  interfere  with  the  welfare  of 
the  pulp. 

3.  The  administration  of  the  remedy  must  not  require  a  complicated 
instrumentarium . 

4.  The  pharmacologic  action  of  the  remedy  must  be  exhibited  within 
a  few  minutes. 

5.  The  remedy  must  be  readily  applicable  to  all  classes  of  cavities 
with  regard  to  their  location. 

6.  The  remedy  must  not  produce  pain. 

7.  Permanent  discoloration  of  dentin  must  not  occur. 
For  convenience,  we  may  divide  the  applied  remedies  into: 

A.  Physical  and  chemical  procedures: 

1.  Keen  edged  instruments. 

2.  Caustics. 

B.  Local  and  general  remedies: 

1.  Local  anesthetics  and  sedatives. 

2.  General  anesthetics  and  sedatives. 

Sharp  Instruments.- — ^The  superiority  of  sharp  instruments  over  dull, 
ragged-edged  tools  when  working  upon  living  tissue  is  generally 
recognized  by  every-day  experience.  Sharp  excavators  cut  without 
much  pain  when  employed  with  a  definite,  precise  movement  at  right 
angles  to  the  long  axis  of  the  tubuli.  Dull  engine  burs  produce  heat  by 
friction  and  by  being  held  in  too  continuous  contact  with  the  cavity 
wall.  They  should  not  only  be  sharp  but  run  at  high  speed  and 
allowed  to  touch  the  surface  very  lightly  as  they  revolve.  A  thin 
coating  of  vaselin  further  reduces  undue  friction. 

Caustics. — Caustics  are  substances  which  destroy  living  tissue  by 
virtue  of  their  coarse  chemical  or  physical  action.  This  action  may 
manifest  itself  by  abstracting  water  from  albumin,  by  dissolution  or 
precipitation  of  the  albumin,  by  oxidation  or  substitution.  Caustics 
which  are  employed  for  the  purpose  in  view  are  principally  dehydrants 
and  albumin  solvents  or  precipitants.  Alkalies  containing  hydroxyl 
groups — KOH  and  XaOH — are  very  powerful  albumin  solvents,  and 
they  are  not  self-limiting.  The  albumin  precipitants  are  represented 
primarily  by  the  metallic  salts,  by  certain  organic  compounds,  as 
phenol,  alcohol,  etc.,  and  by  heat.  Mineral  acids  should  not  be  applied 
on  living  tooth  structure  for  such  purposes.  The  precipitates  obtained 
by  metallic  salts  differ  widely  in  regard  to  their  density;  silver  nitrate, 


460  PATHOLOGY  OF  HYPERSENSITIVE  DENTIN 

for  instance,  produces  a  dry,  dense  scab,  while  zinc  chlorid  combines 
with  the  albumin  to  form  a  loose,  flocculent  clot. 

As  we  have  stated  above,  hypertension  of  the  contents  of  the  dental 
tubuli  is  the  primary  cause  of  hypersensitive  dentin.  The  removal  of 
this  tension  will  necessarily  interfere  with  or  prevent  the  transmission 
of  impulses;  hence  the  most  simple  and  most  logical  method  of  reducing 
hyperesthesia  of  dentin  for  the  purpose  of  excavating  is  to  dispel  the 
moisture  from  the  tubuli.  It  has  been  found  that  desiccation  of  a 
cavity  by  subjecting  it  to  a  current  of  warm  air  in  conjunction  with 
absolute  alcohol  will  bring  about  a  condition  of  immunity  to  sensation 
in  proportion  as  such  desiccation  is  thorough  or  partial.  To  accomplish 
desiccation  of  the  dentin  best  the  rubber  dam  should  be  adjusted  to  the 
tooth  and  the  greater  portion  of  the  carious  mass  carefully  removed 
with  spoon  excavators;  the  cavity  should  be  bathed  with  absolute 
alcohol^  and  then  subjected  to  a  stream  of  warm  air  applied  in  some 
convenient  manner.  The  ordinary  air  syringe  or  chip-blower  may 
have  its  point  heated  in  a  flame,  and  then,  by  forcing  the  air  in  the 
bulb  slowly  through  the  tube,  a  jet  of  warm  air  will  be  delivered  into 
the  cavity.  By  holding  the  nozzle  of  the  syringe  at  the  proper  distance 
and  having  learned  by  experience  how  much  heat  to  apply,  one  can 
often  inject  a  current  of  air  into  the  cavity  at  nearly  the  same  tempera- 
ture as  that  of  the  tooth ;  but  if  the  air  when  it  reaches  the  cavity  should 
be  either  perceptibly  above  or  below  the  proper  temperature,  pain  will 
be  produced.  In  some  warm-air  sjTinges  the  tube  is  provided  with  a 
hollow  receptacle  somewhere  along  its  length,  which,  when  heated, 
raises  the  temperature  of  the  air  within  it  before  being  directed  into 
the  tooth  cavity.  Neither  of  these  methods  is  at  all  exact,  and  either 
is  therefore  liable  to  produce  more  or  less  pain  in  the  act  of  dehydration. 
A  better  plan  would  be  to  employ  a  sjTinge  in  which  a  coil  of  fine 
platinum  is  contained  within  the  orifice ;  this  coil  is  connected  by  wires 
through  the  body  of  the  syringe  with  a  source  of  electric  current;  in 
operation  the  resistance  encountered  by  the  current  of  electricity 
passing  through  the  platinum  coil  heats  it  and  maintains  a  steady 
temperature.  Air  forced  over  this  coil  and  through  the  nozzle,  especi- 
ally air  supplied  from  a  receiver  and  under  pressure  that  can  be  con- 
trolled, may  be  heated  to  a  temperature  that  will  approximate  very 
closely  that  of  the  tooth,  and  therefore  produce  little  or  no  pain.  If  the 
air  passing  from  the  nozzle  of  the  syringe  should  be  too  warm  it  can  be 
modified  by  holding  it  a  little  farther  away  from  the  tooth,  or  if  not 
warm  enough,  more  heat  will  be  delivered  when  it  is  held  in  closer 
proximity. 

1  Absolute  alcohol  for  this  purpose  may  be  prepared  by  adding  either  J  ounce  anhy- 
drous copper  sulphate  or  an  equal  quantity  of  well-burned  unslaked  lime  to  3  ounces  of 
commercial  alcohol. 


SYMPTOMS  AND  TREATMENT 


461 


An  instrument  of  this  character  with  a  compressible  bulb  instead  of 
an  air  supply  from  a  receiver  is  represented  in  Fig.  401.  The  operation 
of  desiccation  should  not  be  hurried;  time  must  be  allowed  for  raising 
the  air  to  a  suitable  temperature,  so  as  to  cause  as  little  pain  as  possible. 
In  addition  the  operation  should  be  continued  until  the  dentinal  walls 
of  the  cavity  have  become  perceptibly  lighter  in  color,  indicating  that 
they  have  been  robbed  of  their  moisture.  If  desiccation  is  not  carried 
to  this  point  it  will  fail  in  its  effectiveness;  but  if  the  moisture  has  been 
removed  from  the  dentin  to  a  considerable  depth,  as  it  may  be  if  desic- 
cation be  continued  sufficiently,  sensitiveness  will  have  become  nearly 
or  entirely  obliterated.  Whether  we  depend  entirely  upon  dryness  to 
relieve  hypersensation  or  not  it  should  be  resorted  to,  for  it  proves  a 
most  valuable  preliminary  means  when  it  is  to  be  followed  by  medica- 
tion of  anv  kind. 


Fig.  401. — Electric  warm-air  syringe.     (Guilford.) 


Caustic  alkalies  are  preferably  applied  in  the  well-known  form  of 
Robinson's  remedy,  which  is  composed  of  equal  parts  of  potassium 
hydroxid  and  crystalline  phenol  forming  potassium  phenate  when 
triturated  together  in  a  warmed  mortar,  with  the  addition  of  a  very 
small  quantity  of  glycerin  to  render  it  plastic.  It  should  be  preserved 
in  well-stoppered  bottles.  A  small  quantity  of  this  compound  applied 
to  the  previously  dehydrated  painful  dentin  surface  and  rubbed  into 
it  with  a  warm  burnisher  will  often  prove  to  be  of  benefit.  An  intimate 
pasty  mixture  of  potassium  carbonate,  four  parts,  and  pure  glycerin 
one  part  kept  in  a  tightly  corked  bottle,  has  also  been  lauded  very  much. 
The  caustic  and  dehydrating  effect  of  these  agents  combined  with  the 
warm  air  blast  lowers  hyperesthesia  markedly. 

Their  benumbing  action,  however,  is  only  superficial,  and  they  have 
to  be  applied  repeatedly  as  the  preparation  of  the  cavity  progresses. 

Albumin  precipitants  are  principally  represented  by  silver  nitrate, 
zinc  chlorid  and  phenol.  The  silver  salt  acts  very  superficially  and  very 
slowly.     Incidentally,  by  combining  with  the  chlorin  present  in  the 


462       PATHOLOGY  OF  HYPERSENSITIVE  DENTIN 

albumin  and  in  the  presence  of  light,  it  produces  jet-black  discoloration 
of  the  involved  dentin.  On  all  exposed  dentin  surface,  especially  on 
the  exposed  roots  of  the  posterior  teeth  where  the  resultant  color  is  no 
objection,  it  is  an  admirable  desensitizer.  It  is  best  applied  as  a  freshly 
prepared  saturated  aqueous  solution.  Other  silver  salts  are  of  less 
value  in  this  connection,  as  they  are  less  caustic.  It  should  be  remem- 
bered that  the  pharmaco-dynamic  action  of  silver  nitrate  depends  upon 
the  precipitation  of  albumin  by  the  nitric  acid  ion  and  not  upon  the 
silver  ion.  The  latter  merely  combines  with  the  albumin  forming  a 
complicated  double  salt,  i.  e.,  silver-albumin  chlorid,  which  in  the 
presence  of  light  is  partially  reduced  to  a  black  oxid.  Zinc  chlorid 
is  an  admirable  desensitizer;  its  application  in  crystal  form  or  as  a 
saturated  solution  is  somewhat  painful  on  account  of  its  acid  reaction. 
As  it  is  not  self-limiting  it  should  not  be  applied  into  deep-seated 
cavities  on  account  of  the  danger  of  pulp  irritation  at  the  time  of  its 
application  or  subsequently.  Liquefied  phenol  does  not  penetrate 
deeply  into  tooth  structure  and  may  be  applied  safely  to  cavities  of 
any  depth.  When  applied  into  a  dehydrated  cavity  in  conjunction 
with  the  warm-air  blast  it  produces  quick  and  marked  superficial 
benumbing  effects,  hence  it  is  widely  employed  for  this  purpose.  The 
addition  of  local  anesthetics  to  phenol  for  this  purpose,  i.  e.,  cocain, 
etc.,  is  an  irrational  procedure. 

Within  the  last  few  years  Buckley^  has  lauded  dry  formaldehyde 
(trioxymethylen)  in  the  form  of  a  paste  as:  "A  new,  safe  and  reliable 
remedy  for  hypersensitive  dentin."  This  empirically  compounded 
paste  contains  approximately  35  per  cent,  of  dry  formaldehyd  mixed 
with  vaselin  and  a  few  minor  substances  of  no  direct  value.  Inter- 
national dental  literature  of  the  last  decade  is  filled  with  references 
relative  to  the  use  of  formaldehyd  as  a  desensitizing  agent,  and  all 
writers,  except  Buckley,  agree  that  it  is  a  most  dangerous  agent  for 
this  purpose,  as  it  will  injure  and,  in  most  instances,  kill  the  pulp. 
It  produces  numbness  of  dentin  in  the  same  manner  as  arsenic,  only 
acting  somewhat  slower. 

Trioxymethylen  acts  as  a  non-self-limiting  caustic  which  penetrates 
comparatively  quickly  through  any  thickness  of  dentin.^  As  an  illus- 
tration of  the  intense  caustic  action  it  may  be  stated  that  in  the  hands 
of  some  practitioners  the  Buckley  desensitizing  paste  constitutes  the 
routine  application  for  the  purpose  of  destroying  the  pulps  in  deciduous 
teeth.  The  same  deleterious  results  are  obtained  with  the  so-called 
"Norwegian  Dentin  Anesthetic."     This  compound  contains  carpain 

1  Items  of  Interest,  December,  1914. 

2  Prinz:     Dental  Cosmos,  August,  1915. 


SYMPTOMS  AND  TREATMENT  463 

and  paucin,  two  alkaloids  which  act  somewhat  like  erythrophlein,  i.  e., 
they  kill  the  pulp. 

Occasionally,  protoplasmic  poisons  are  recommended  for  the  pm'pose 
of  desensitizing  dentin.  In  many  instances  these  drugs  are  referred 
to  erroneously  as  caustics.  A  protoplasmic  poison  should  be  designated 
as  a  drug  which  endangers,  or  even  kills  living  cell  structure  without 
visible  changes.  Protoplasmic  poisons  are  not  self-limiting  in  their 
action.  Arsenic  trioxid  and,  to  a  less  extent,  the  alkaloids  nervocidin, 
erythrophlein  and  paucin,  are  the  principal  substances  of  this  group 
that  have  been  employed  as  desensitizing  agents.  Arsenic  when 
applied  even  in  the  very  minutest  quantities  will  usually  kill  the  pulp, 
as  its  action  cannot  be  controlled.  This  is  equally  true  of  the  above- 
named  alkaloids;  they  have  only  historical  interest  at  present. 

Local  Anesthetics  and  Sedatives. — ^True  local  anesthetics,  cocain  or 
its  substitutes,  when  applied  to  exposed  sound  dentin  without  pressure, 
do  not  produce  any  pharmacologic  effects.  Even  if  sealed  into  a  fairly 
deep-seated  cavity  in  which  the  underlying  dentin  is  not  decalcified 
no  effect  is  obtained.  Living  protoplasm  reacts  unfavorably  against 
the  ready  absorption  of  substances  by  endosmosis  for  two  reasons: 
(1)  the  albumin  molecule  is  relatively  very  large  and  is  not  easily 
diffusible,  and  (2)  it  possesses,  as  an  integral  part  of  its  life,  vital 
resistance  toward  foreign  bodies.  According  to  Hertwig,  protoplasm 
primarily  transfers  irritation  and,  secondarily  transmits  absorbed 
materials.  Therefore  the  anesthetic  solution  has  to  pass  through  the 
entire  length  of  tbe  dentinal  fiber  before  the  nerve  tissue  of  the  pulp 
proper  is  reached.  Consequently  a  certain  period  of  time  is  required 
before  the  physiologic  effect  of  the  anesthetic  is  manifested  and  the 
period  of  this  latency  is  dependent  upon  the  thickness  of  the  inter- 
mediate layer  of  dentin.  The  migration  of  a  protoplasmic  poison 
through  dentin  may  be  observed  by  adding  a  vital  stain  to  it,  as,  for 
instance,  methylene  blue  added  to  arsenic  or  dry  formaldehyd.  The 
time  required  for  its  passage  through  about  5  mm.  of  sound  adult 
dentin  is  twenty-four  or  more  hours.  The  pharmaco-dynamic  power  of 
a  drug  depends  upon  its  reaction  with  the  living  protoplasm  through  the 
catalytic  action  of  ferments.  The  decomposition  of  the  absorbed  drug 
occurs  comparatively  quickly,  usually  within  a  few  minutes.  These 
observations  are  seen  daily  on  injecting  anesthetics  or  other  solutions 
hypodermically.  An  average  hypodermic  dose  of  cocain  is  completely 
decomposed  by  the  ferments  of  the  protoplasm  within  the  period  of  an 
hour,  i.  e.,  its  typical  local  anesthetic  effect  is  manifested  within  a  few 
minutes  after  the  injection.  The  anesthesia  remains  at  its  height  for 
about  thirty  minutes,  and  from  then  on  it  diminishes  until  by  the  end 
of  the  hour  there  is  fairly  complete  recovery  of  normal  sensation. 


464  PATHOLOGY  OF  HYPERSENSITIVE  DENTIN 

Therefore,  if  we  apply  cocain  to  sound  dentin  it  is  decomposed  on  its 
passage  over  Tomes'  fibers  before  it  reaches  the  anatomic  threshold 
of  sensation,  i.  e.,  the  nerve  plexus  at  the  surface  of  the  pulp,  and 
hence  no  anesthesia  is  produced.  The  nature  of  the  cocain  salt,  whether 
it  is  a  hydrochlorid,  nitrate  or  lactate,  has  no  bearing  upon  its  therapeu- 
tic action.  The  apparent  results  obtained  with  these  cocain  salts  must 
be  attributed  to  the  preliminary  dehydration,  protection  of  the  exposed 
dentin  by  a  temporary  filling,  etc.,  and  not  to  its  therapeutic  effects. 
This  is  equally  true  in  regard  to  most  of  the  heterogeneous  mixtures  of 
cocain  with  other  substances,  as,  for  instance,  potassocoin,  vapocain, 
etc.  Again,  in  the  widely  recommended  solution  of  cocain  (alkaloid) 
in  chloroform  and  ether  the  cocain  base  plays  no  part.  The  apparent 
results  obtained  are  produced  by  the  process  of  evaporating  to  dryness 
and  thereby  obtaining  a  marked  reduction  in  temperature,  which  is  the 
obtundent  factor.  When  cocain  or  any  of  its  substitutes  is  forced  into 
the  living  protoplasm  of  the  unobstructed  dentin  tubuli  under  pressure, 
its  anesthetic  action  is  manifested  within  a  few  minutes.  The  vital 
resistance  of  protoplasm  is  readily  overcome  by  comparatively  slight 
force,  which  quickly  transfers  the  anesthetic  solution  by  an  increased 
osmotic  interchange  to  the  surface  of  the  pulp.  The  phenomenon  is 
to  be  explained  as  an  anesthesia  obtained  by  intimate  contact  under 
pressure,  either  mechanical  or  by  electromotive  force  (cataphoresis) . 
The  pulp  of  a  tooth  and,  consequently,  the  dentin  may  be  desensitized 
completely  by  any  one  of  the  well-known  methods  of  contact  anesthesia 
by  using  hand  pressure  or  that  derived  from  a  dental  hypodermic 
syringe  or  some  other  more  complicated  apparatus  or  by  electricity. 
(See  chapter  XII.) 

Electric  Endosmosis. — Some  years  ago  cataphoresis,  for  the  purpose 
of  desensitizing  dentm,  was  much  lauded.  This  process  consists  of 
placing  a  concentrated  solution  of  cocain  on  cotton  in  the  sensitive 
cavity  and  having  it  carried  along  the  dentinal  tubuli  toward  the  pulp 
by  means  of  a  galvanic  current,  i.  e.,  by  electromotive  force.  A  battery 
is  employed  with  the  negative  electrode,  the  cathode,  inserted  in  the 
cavity,  and  the  anode  placed  upon  some  part  of  the  patient's  body,  as 
the  band,  etc.  The  current  carries  the  cocain  via  Tomes'  fibers  into 
the  pulp  and  anesthetizes  it.  While  in  this  condition,  which  usually 
lasts  for  an  hour  or  more,  the  tooth  may  be  worked  upon  without  any 
pain.  For  a  while  this  method  met  with  great  favor  because  of  the 
perfect  results  obtained,  but  it  was  found  to  be  a  very  slow  process, 
requiring  a  cumbersome  apparatus  and  often  consuming  more  time 
than  the  operator  had  at  his  command,  and  occasionally  requiring  a 
second  application  in  order  to  produce  complete  anesthesia;  hence  at 
present  it  has  been  largely  discarded. 


SYMPTOMS  AND  TREATMENT  465 

Of  the  numerous  essential  oils  which  have  been  suggested  as  obtun- 
dents of  dentin,  oil  of  cloves  stands  out  prominently. 

Its  pharmacologic  action  depends  on  the  presence  of  eugenol,  an 
unsaturated  aromatic  phenol.  The  basic  constituent  of  eugenol 
consists  of  para-amido-benzoic  acid,  a  body  which  as  such  does  not 
exhibit  any  marked  therapeutic  effects.  Its  methyl  ester,  anesthesin, 
is  an  efficient  local  anesthetic;  however,  it  is  only  slightly  soluble  in 
water.  Einhorn  and  Uhlfelder,  taking  anesthesin  as  a  base  for  their 
synthetic  research,  finally  succeeded  in  preparing  para-amido-benzoyl- 
diethyl-amino-ethanol,  commercially  known  as  novocain  or  procain, 
which  at  present  is  the  most  efficient  substitute  for  cocain. 

Essential  oils,  in  general,  possess  marked  penetrating  power.  How- 
ever, upon  a  fairly  thick  layer  of  sound  dentin  they  are  of  little  value 
when  employed  as  obtundents.  A  different  pharmaco-dynamic  action 
is  observed  with  arsenic.  Arsenic  trioxid,  AS2O3,  in  the  presence  of 
certain  ferments  of  living  protoplasm,  i.  e.,  oxydases  and  catalases,  is 
changed  to  the  pentoxid,  AS2O5,  which  again  is  quickly  reduced  to  the 
trioxid.  This  perpetual  oxidation  and  reduction  within  the  protoplasm 
of  the  cell  causes  a  violent  oscillation  of  the  molecule  of  active  oxygen, 
and  thereby  its  therapeutic  effects  are  manifested.  The  metalloid 
arsenic  merely  plays  the  role  of  an  auto-oxidizer.  The  presence  of  the 
absorbed  arsenic  can  be  detected  in  the  tissues  by  chemical  analysis, 
that  of  absorbed  cocain  cannot. 

Among  the  local  sedatives,  refrigerant  anesthetics  should  be  men- 
tioned. These  agents  lower  the  temperature,  diminish  sensation  and 
reduce  the  volume  of  the  parts  to  which  they  are  applied. 

Physically  reducing  hyperesthesia  of  dentin  by  the  application  of 
cold  is  best  accomplished  by  employing  a  chemical  which  has  a  low 
boiling-point.  Pure  ether  (boiling-point  95°  F.,  35°  C),  free  from 
water,  produces  good  results.  Certain  other  hydrocarbons  possess 
similar  properties  in  varying  degrees,  depending  upon  their  individual 
boiling-point.  Pure  ethyl  chlorid  (boiling-point  55°  F.,  13°  C.)  is 
best  for  this  purpose,  as  it  lowers  the  temperature  of  the  tissues  suffi- 
ciently to  produce  a  short,  superficial  anesthesia  in  a  few  minutes. 
Too  rapid  cooling  or  prolonged  freezing  produces  deep  anesthesia,  but 
such  procedures  are  dangerous;  circulation  in  the  pulp  may  be  cut  off 
so  completely  as  to  produce  death.  Liquid  nitrous  oxid,  liquid  carbon 
dioxid,  and  liquid  air,  all  of  which  have  a  boiling-point  far  below  zero, 
are  recommended  for  such  purposes,  but  they  require  cumbersome 
apparatus,  and  some  of  these  agents  are  extremely  dangerous  to  handle. 

In  general,  it  should  be  stated  that  the  application  of  cold  for  the 
purpose  of  obtunding  hypersensitive  dentin  is  a  barbaric  procedure. 
The  initial  pain  produced  by  the  cold  is,  in  many  instances,  most 
30 


466        PATHOLOGY  OF  HYPERSENSITIVE  DENTIN 

intense  and  more  pronounced  than  that  experienced  by  cutting  the 
untreated  dentin. 

Indirectly,  hyperesthesia  of  dentin  may  be  ehminated  completely 
by  blocking  locally  the  sensory  nerve  fibers  leading  to  the  pulp  of  the 
respective  tooth.  Any  one  of  the  well-known  methods  or  combinations 
of  methods,  i.  e.,  infiltration  and  conduction  anesthesia,  is  available 
for  this  purpose.  On  an  average,  most  satisfactory  results  in  a  single 
tooth  are  obtained  by  using  the  pericemental  injection,  provided  the 
pericementum  is  sound.     (See  Chapter  XII.) 

The  paralj^zation  of  the  central  end-organs  in  the  brain  by  a  general 
anesthetic  will  also  anesthetize  all  the  tooth  pulps.  Nitrous  oxid  is 
possibly  more  often  used  for  this  purpose  than  any  other  anesthetic 
agent.  The  much-lauded  "  analgesia"  of  a  few  years  ago  was,  as  might 
have  been  expected,  a  failure.  With  the  improvement  in  the  various 
methods  of  local  anesthesia,  general  anesthesia  for  this  specific  purpose 
has  lost  much  of  its  former  significance. 

The  control  of  hypersensitive  dentin  by  the  administration  of 
narcotics  or  sedatives  is  called  for  rarely.  Of  the  general  sedatives 
the  bromids  are  usually  recommended.  Large,  continuous  doses  are 
required  to  manifest  their  action,  as  they  impair  the  perception  of 
sensory  stimuli  only  to  a  very  mild  degree.  Average  doses  of  morphin 
require  at  least  one-half  hour  before  a  depression  of  the  sensory  impulse 
is  manifested,  while  chloral  hydrate  shows  a  marked  lowering  within 
ten  to  fifteen  minutes.  Morphin-scopolamin  administered  hypoder- 
mically  causes  most  pronounced  general  narcotic  effects  and,  of  course, 
marked  lowering  of  the  sensory  reaction  of  the  pulp. 

Sensation  in  a  tooth  may  be  measured  experimentally  by  passing  a 
weak  electrically  induced  current  through  it,  and  the  above  data  are 
based  upon  observations  obtained  by  such  measurements. 

Recently  the  author  has  been  informed  that  certain  practitioners 
advocate  painless  operations  about  the  teeth  by  administering  such 
powerful  narcotic  mixtures  as  morphin-scopolamin  (hyoscin),  also 
known  by  various  trade  names.  These  drugs  are  intended  to  imitate 
what  is  known  in  general  surgery  as  "twilight  sleep."  Such  procedures 
are  eminently  dangerous.  It  should  be  remembered  that  ''doses  of 
these  drugs,  which  without  the  aid  of  one  of  the  gaseous  anesthetics 
cause  a  narcosis  of  sufficient  depth,  carry  with  them  greater  dangers 
than  any  of  the  other  various  methods  of  producing  anesthesia." 
The  author  most  emphatically  discourages  such  practice.  The 
dentist  who,  on  account  of  ignorance,  administers  powerful  narcotics 
of  this  type  may  suddenly  find  himself  entangled  in  the  meshes  of  the 
law. 


CHAPTER   XL 

DISCOLORED  TEETH  AND  THEIR  TREATMENT.^ 

By  HERMANN  PRINZ,  M.D.,  D.D.S. 

Pigments  which  cause  discoloration  of  a  tooth  may  be  classified 
as  endogenous  pigments,  pigments  formed  within  the  tooth,  and 
exogenous  pigments,  pigmentary  substances  acquhed  from  external 
sources.  In  the  great  majority  of  cases,  endogenous  pigments  are 
the  source  of  permanent  tooth  discoloration  and  are  obtained  from 
the  blood.  Temporary  discoloration  from  endogenous  pigments  is 
occasionally  observed  as  a  sequence  of  general  diseases,  as  Asiatic 
cholera,  acute  exanthematous  skin  eruptions,  typhus  fever  and  similar 
distiu-bances  which  produce  a  pinkish  color  or  in  pronounced  cases 
of  jaundice  (icterus)  a  diffusion  of  bile  pigment  (bilirubin,  which  is 
isomeric  with  hematoidin)  may  occur  in  teeth  having  living  pulps 
which  produces  a  distinct  orange-yellow  stain.  These  various  stains 
usually  disappear  with  the  termination  of  the  underlying  disease. 
Exogenous  pigmentations  usually  result  from  the  application  of  drugs 
employed  in  the  treatment  of  teeth,  from  medicines,  from  food  or  from 
che'^ing  stimulants,  such  as  tobacco,  betel  nuts,  etc. 

Death  of  the  pulp  is  the  principal  source  of  permanent  discoloration. 
While  this  does  not  always  nor  necessarily  invoh^e  discoloration  of  the 
tooth  structures,  yet  when  the  condition  does  exist  the  general  cause  is 
as  stated.  Progressive  interstitial  staining  of  the  entire  dentin  struc- 
ture is  the  usual  result,  exclusive  of  certain  metallic  stains,  also  localized 
stains  resulting  from  the  imbibition  of  pigmentary  matters  occasionally 
observed  when  small  areas  of  dentin  have  become  denuded  of  enamel 
covering  or  when  the  latter  has  been  so  imperfectly  formed  as  to  afford 
an  insufficient  barrier  to  the  ingress  of  pigmentary  matters  from  the 
food  or  oral  secretions. 

Three  classes  of  conditions  are  presented  for  consideration  and 
treatment:  (1)  discoloration  which  has  resulted  from  death  of  the 
pulp  due  to  causes  other  than  its  exposure;  (2)  discoloration  from  death 
of  the  pulp  caused  by  exposiue;  (3)  special  discol orations  from  death 
of  the  pulp  due  to  adventitious  causes  superadded  to  the  conditions 
affecting  the  cases  included  in  the  foregoing  second  division. 

1  The  greater  portion  of  this  chapter  has  been  written  for  former  editions  by  Dr. 
Edward  C.  Kirk. 

(467) 


468  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

DISCOLORATION   FROM  DEATH  OF  PULP  DUE  TO   CAUSES 
OTHER  THAN  EXPOSURE. 

Any  of  the  numerous  traumatic  causes  which  bring  about  death 
of  the  pulp,  viz.,  blows,  sudden  contact  with  hard  substances,  biting 
threads,  violent  thermal  shocks,  the  injudicious  application  of  con- 
tinuous force  in  regulating,  the  application  of  arsenous  oxid  to  the 
dentin,  where  no  exposure  or  only  minute  exposure  of  the  pulp  exists, 
organic  or  inorganic  poisons,  certain  bacteria  or  even  the  exposure  to 
severe  cold  (ethyl  chlorid),  may  produce  hyperemia  and  congestion 
of  the  pulp,  or  strangulation  of  its  circulatory  system,  the  formation 
of  emboli,  thrombus,  hemorrhagic  infarct,  etc.,  leading  to  a  breaking 
down  of  the  corpuscular  elements  of  the  blood,  the  escape  of  hemo- 
globin from  the  stroma  of  the  red  corpuscles,  its  solution  in  the  blood 
plasma,  and  resulting  infiltration  of  the  tubular  structure  of  the  dentin 
by  the  hemoglobin  solution,  giving  the  tooth  a  distinctly  pinkish  hue 
when  examined  by  direct  light  or  by  transillumination.  An  interesting 
observation  relative  to  tooth  discoloration  is  made  by  Thomas  Bell.^ 
He  states:  "I  have  frequently  examined  the  teeth  of  persons  whose 
death  has  been  occasioned  by  hanging  or  drowning,  and  have  invariably 
found  the  whole  of  the  osseous  part  colored  with  a  dull  deep  red,  which 
could  not  have  been  the  case  if  these  structures  were  devoid  of  a 
vascular  system.  In  both  instances  the  enamel  remains  wholly  free 
from  discoloration." 

Suffusion  of  the  dentin  structure  by  discharged  hemoglobin  may  be 
produced  readih^  by  the  topical  application  to  the  exposed  pulp  of  medi- 
caments having  hemolytic  properties;  for  example,  spirit  of  trinitro- 
glycerin  (glonoin)  as  an  ingredient  of  a  cocain  solution  intended  for  the 
production  of  local  anesthesia,  will  frequently  produce  hemolysis  with 
suffusion  of  the  dentin  when  the  mixture  is  applied  locally  to  a  bleeding 
pulp.  Even  distilled  water  exerts  a  hemolytic  effect,  rupturing  the 
stroma  of  erythrocytes  by  endosmosis;  therefore,  all  solutions  intended 
for  topical  application  to  a  bleeding  pulp  should  be  at  least  isotonic 
with  the  plasma  or  preferably  of  greater  density  in  order  to  avoid 
staining  the  dentin  with  diflfused  hemoglobin. 

Teeth  so  affected  rapidly  change  in  color  through  various  gradations 
in  tint  from  the  original  pinkish  hue,  which  becomes  yellow;  this  grow- 
ing darker,  passes  into  brown,  and  after  the  lapse  of  considerable  time 
the  tooth  may  become  a  permanent  slaty  gray  or  black. 

The  violence  of  the  hyperemia  preceding  the  death  and  disintegra- 
tion of  the  pulp  determines,  to  a  considerable  degree,  the  rapidity  of 

1  Anatomy,  Physiology  and  Diseases  of  the  Teeth,  3d  Am.  Edition,  Philadelphia,  1837. 


DISCOLORATION  FROM  DEATH  OF  PULP  469 

the  process  of  subsequent  tooth  discoloration.  When  congestion  of 
the  pulp  has  been  relatively  slight  and  the  necrotic  process  has  pro- 
ceeded slowly,  the  sudden  infiltration  of  the  dentin  with  hemoglobin 
does  not  occur;  consequently  the  initial  change  in  color  following 
complete  death  of  the  pulp  may  be  so  slight  as  to  escape  detection 
except  upon  most  searching  examination,  with  special  means  of  illumi- 
nation, and  even  then  may  be  manifested  only  by  a  slight  diminution 
in  the  normal  translucency  of  the  tooth  as  compared  with  adjoining 
teeth.  Such  teeth,  however,  if  permitted  to  remain  untreated,  even- 
tually grow  darker,  and  while  they  may  not  acquire  a  degree  of  dis- 
coloration equal  to  those  which  have  suffered  sudden  or  violent  death 
of  the  pulp,  they  become  so  unsightly  as  to  demand  treatment  for  the 
restoration  of  their  normal  color. 

The  Rationale  of  the  Process  of  Discoloration. — In  teeth  discolored  as  a 
consequence  of  the  death  of  the  pulp  without  its  exposure  it  is  evident 
that  the  sources  of  pigmentation  are  internal  to  the  tooth  and  are 
sought  for  solely  in  the  products  of  decomposition  of  the  elements  of 
the  pulp  tissue  and  its  vascular  supply. 

The  proteid  elements  of  the  pulp  tissue  are  complex  combinations  of 
carbon,  oxygen,  hydrogen,  nitrogen,  sulfur,  and  phosphorus,  which,  in 
their  gradual  breaking  down  by  the  process  of  putrefactive  decomposi- 
tion, are  split  up  finally  into  carbon  dioxid,  water,  ammonia,  and 
hydrogen  sulfid,  with  possibly  the  formation  of  traces  of  phosphatic 
salts.  The  group  of  substances  entering  into  the  composition  of  the 
histologic  elements  of  pulp  tissue  contains  no  constituents  which  in 
the  progressive  changes  resulting  from  putrefactive  decomposition 
should  form  compounds  likely  to  cause  permanent  discoloration  of  the 
tooth  structures. 

When,  however,  the  vascular  supply  is  considered  as  a  factor,  the 
explanation  of  the  cause  of  discoloration  in  the  cases  in  question 
becomes  reasonably  clear.  The  red  corpuscles  contain  as  their  charac- 
teristic component  hemoglobin  or  oxyhemoglobin  depending  upon 
whether  the  blood  is  venous  or  arterial,  and  this  substance  is  its  essen- 
tial coloring  ingredient.  When  undergoing  gradual  decomposition, 
hemoglobin  passes  through  a  variety  of  alterations  in  its  chemical 
constitution,  accompanied  by  a  corresponding  series  of  color  changes. 

A  familiar  illustration  of  these  color  changes  is  furnished  by  the  cycle 
of  color  alterations  witnessed  in  a  bruise.  Immediately  following  an 
injury  to  the  flesh,  of  the  character  alluded  to,  an  extravasation  of 
blood  in  the  bruised  territory  occurs,  causing  undue  reddening  of  the 
skin;  this  is  soon  followed  by  an  increasing  darkening  of  the  tissue 
until  there  results  what  is  popularly  termed  a  black-and-blue  spot. 
Further  decomposition  of  the  coloring  matter  of  the  extravasated  blood 


470  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

induces  a  variety  of  color  changes  ranging  through  the  scale  of  yellows 
and  browns,  until  the  pigmentary  matter  is  finally  removed  by  absorp- 
tion through  the  capillary  bloodvessels  and  lymphatic  system  of  the 
part. 

In  passing  through  the  cycle  of  color  changes  due  to  its  progressive 
decomposition,  hemoglobin  undergoes  several  alterations  in  com- 
position, among  which  are  formed  a  number  of  definite  compounds, 
each  having  marked  chromogenic  features.  Of  these  decomposition 
products,  methemoglobin  (brownish  red),  hemin  (bluish  black), 
hematin  (dark  brown  or  bluish  black),  and  hematoidin  (orange),  are 
the  most  important  and  best  known.  While  gradual  decomposition 
of  the  coloring  matter  of  the  blood  here  noted  may  account  for  certain 
phases  of  tooth  discoloration,  other  factors  which  exert  a  profoundly 
modifying  influence  upon  the  process  are  yet  to  be  considered. 

The  putrefactive  decomposition  of  the  proteid  elements  of  the  pulp 
results,  as  before  stated,  in  the  production  of  hydrogen  sulfid  in  con- 
siderable quantity.  The  albumins  contain  from  0.8  to  2.2  per  cent,  of 
sulfur  (Hammersten),  which  in  the  splitting  up  of  the  compound  during 
putrefaction  yields  a  large  amount  of  hydrogen  sulfid.  In  pulp  decom- 
position this  hydrogen  sulfid  is  generated  in  contact  with  the  hemoglobin 
and  necessarily  exerts  a  marked  modifying  action  upon  the  decomposi- 
tion process  of  that  substance.  Miller  says :  "  If  a  current  of  hydrogen 
sulfid  is  conducted  through  fresh  blood  or  a  solution  of  oxyhemoglobin 
in  the  presence  of  air  or  oxygen,  sulfomethemoglobin  is  formed,  which 
is  greenish  red  in  concentrated  solutions  and  green  in  dilute  solutions. 
If  we  la}^  a  recently  extracted  tooth  in  a  mixture  of  meat  and  saliva  so 
that  a  part  of  the  enamel  surface  remains  free,  and  moisten  the  surface 
with  blood,  it  will  take  on  a  dirty  green  color  if  kept  at  blood  tempera- 
ture in  an  absolutely  moist  condition  for  from  twenty-four  to  forty- 
eight  hours.  It  is  quite  possible  that  the  dirty  green  deposits  which 
form  in  putrid  conditions  of  the  mouth,  in  stomatitis  mercurialis, 
scorbutica,  gangrenosa,  etc.,  or  even  in  inflammatory  conditions  of 
less  importance,  as  well  as  in  cases  of  absolute  neglect  of  the  care  of  the 
mouth,  may  owe  their  green  color  to  the  presence  of  sulfomethemo- 
globin." 

As  in  pulp  decomposition  hydrogen  sulfid  is  being  formed  in  the 
presence  of  hemoglobin,  this  fact  warrants  the  belief  that  a  combination 
takes  place  resulting  in  the  formation  of  this  same  compound,  which 
Miller  regards  as  productive  of  certain  stains  upon  the  external  surface 
of  the  teeth. 

The  slaty  gray  or  bluish  pigmentation  always  noticeable  upon  the 
visceral  walls  and  frequently  beneath  the  skin  of  animal  bodies  under- 
going putrefactive  decomposition  is  a  familiar  example  of  the  action 


DISCOLORATION  FROM  DEATH  OF  PULP  471 

of  hydrogen  sulfid  or  its  ammonia  combinations  upon  decomposing 
hemoglobin  in  hemorrhagic  extravasations,  and  is  a  process  and  form 
of  pigmentation  exactly  analogous  to  that  which  is  here  described  as 
taking  place  in  the  dentinal  structure  from  putrefactive  decomposition 
of  the  pidp.  "When  red  corpuscles  are  just  beginning  to  disintegrate, 
the  coloring  matter  formed  is  hemoglobin;  but  the  yellow  and  brown 
granular  masses  foimd  in  cells  and  lying  free  in  tissues  are,  as  a  rule, 
derivatives  of  hemoglobin,  not  hemoglobin  itself.  These  derivatives 
are  divided  into  two  groups  depending  upon  whether  or  not  they  con- 
tain iron,  the  former  being  called  hemosiderin,  the  latter  hematoidin. 
When  acted  upon  by  ammonium  sulfid  (a  derivative  of  putrefactive 
decomposition  of  albumin),  hemosiderin  becomes  black,  iron  sulfid 
being  formed."^  Hemosiderin  is  a  mixture  of  pigments  in  which  iron 
exists  in  a  most  accessible  form  to  be  demonstrated  readily  by  the 
Prussian-blue  reaction.  Grohe^  believes  that  as  a  result  of  putrefaction 
iron  is  liberated  from  its  compound  with  hemoglobin,  so  that  when 
thus  freed  it  combines  readily  with  the  hydrogen  sulfid. 

Iron  is  the  most  important  element  to  be  considered  in  the  list  of 
factors  causing  the  discoloration  of  this  group  of  cases.  It  is  the  iron 
constituent  of  the  red  corpuscles  which  is  the  essential  chromogenic 
factor  from  first  to  last  in  their  cycle  of  color  changes. 

The  process  of  putrefactive  decomposition  consists  of  a  series  of 
chemical  changes  brought  about  through  the  agency  of  microorgan- 
isms, involving  the  breaking  down,  by  successive  stages,  of  highly 
complex  organic  compounds  and  their  resolution  into  compounds  of 
much  simpler  composition.  It  is  not  known  to  what  extent  this  split- 
ting up  of  the  components  of  the  pulp  and  its  vascular  elements  is 
ultimately  carried  in  the  series  of  changes  resulting  in  the  permanent 
discoloration  of  the  tooth.  From  what  is  known  of  the  ultimate  compo- 
sition of  the  compounds  involved,  it  may  be  inferred  that  reduced  to 
its  lowest  terms,  the  residt  so  far  as  pigmentation  is  concerned,  would 
be  the  formation  of  iron  sulfid,  the  elements  of  which,  with  the  excep- 
tion of  some  unimportant  alkaline  and  earthy  salts,  are  the  only  ones 
entering  into  the  original  compounds  which  are  fixed  and  therefore 
capable  of  forming  a  stable  residuum  in  the  tubular  structure  of  the 
dentin.  While  iron  sulfid  cannot  be  held  wholly  accountable  for  the 
final  bluish-black  color  of  a  tooth,  the  pigmentation  is  almost  certainly 
due  to  it  or  to  some  allied  compound  in  which  iron  and  sulfm',  with 
some  organic  constituents,  largely  enter,  and  which,  by  a  further 
slight  decomposition,  would  yield  true  iron  sulfid. 

1  Ziegler:     General  Pathology,  1895. 

2  Virchow's  Archiv,  Band  xx. 


472  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

The  significance  and  importance  of  a  recognition  of  the  possible 
presence  of  the  iron  compound  as  a  factor  in  tooth  discoloration  are 
further  brought  out  in  the  stud}^  of  bleaching  methods. 

Discoloration  of  Teeth  Following  Death  of  the  Pulp  Consequent  Upon 
Its  Exposure. — When  death  and  decomposition  of  the  pulp  are  conse- 
quent upon  exposure  of  that  organ,  through  caries  or  otherwise,  to  the 
irritative  influences  of  infective  agents  present  in  the  oral  secretions 
and  food,  or  to  thermal  shock,  etc.,  the  putrefactive  process  involving 
the  pulp  tissues  is  modified  in  character  and  rapidity  to  a  degree  which 
may  aftect  the  character  of  the  resulting  discoloration.  Thus,  the 
yellowish  or  brownish  discoloration  so  often  seen  in  teeth  whose  pulps 
have  been  devitalized  through  systemic  or  traumatic  causes,  and  which 
in  many  cases  appears  to  be  more  or  less  permanent  in  character,  is 
rarely  observed  in  those  teeth  whose  pulps  have  been  devitalized 
through  exposure  by  caries. 

In  these  latter  cases  the  original  sufi^usion  of  the  dentin  by  hemo- 
globin has  not  taken  place  ordinarily  and,  moreover,  the  progress  of  the 
putrefactive  process  is  comparatively  rapid,  the  conditions  being  more 
favorable,  so  that  the  coloring  matter  of  the  blood  is  sooner  reduced 
to  its  lowest  terms  in  the  scale  of  decomposition  products,  i.  e.,  to  the 
slaty  blue  or  black  pigmentation  before  noted.  The  pigmentation  of 
the  dentin  in  cases  of  pulp  exposure  with  subsequent  decomposition 
of  that  organ  is  due  to  the  diffusion  of  some  of  the  decomposition 
products  of  hemoglobin  that  have  been  formed  in  the  pulp  chamber  and 
not  in  the  tubuli  as  in  the  class  of  cases  first  considered.  In  addition 
to  the  increased  rapidity  of  putrefactive  decomposition  incident  to 
cases  of  discoloration  following  pulp  exposure,  another  important  modi- 
fying factor  in  the  process  of  discoloration  is  the  ingress  afforded  to  the 
oral  fluids,  food  materials,  and  other  adventitious  substances  which 
find  their  way  into  the  mouth,  and  ultimately,  through  the  open 
cavity  of  the  tooth,  to  its  pulp  canal,  and  thence  to  the  tubular  struc- 
ture of  the  dentin.  These  extraneous  substances,  in  the  course  of  time, 
may  infiltrate  the  tooth  structure,  and  while  no  especially  noticeable 
or  characteristic  effect  may  be  observed  so  far  as  color  is  concerned,  yet 
frequently  they  exert  an  influence  upon  the  coloration  of  the  tooth 
which  so  alters  its  character  as  to  render  successful  bleaching  treatment 
extremely  difficult  and  a  resort  to  special  methods  or  a  variety  of 
methods  necessary. 

Fatty  or  oily  substances  or  astringent  and  coagulant  agents,  for 
example,  may  act  upon  the  coloring  matter  in  such  a  way  as  to  set 
it  permanently  in  the  same  manner  that  mordants  form  insoluble 
compounds  or  lakes  with  the  dyestuffs  used  in  the  dyeing  of  textile 
fabrics. 


DISCOLORATION  FROM  DEATH  OF  PULP  473 

Another  important  class  of  substances  which  is  frequently  the  cause 
of  staining  the  tooth  structure  is  metallic  salts  used  in  dental  thera- 
peutic treatment  or  accidentally  formed  during  the  application  of 
corrosive  medicaments  to  the  teeth,  through  the  action  of  such  reme- 
dies upon  fillings  in  situ  or  upon  the  instruments  by  which  the  applica- 
tions are  made.  An  example  of  this  is  the  use  of  iodin  or  sulfuric  acid 
or  other  metallic  solvents  in  connection  with  steel  instruments  and  the 
subsequent  use  of  medicaments  containing  tannin  as  an  ingredient. 

Treatment. — ^The  treatment  of  these  conditions  will  be  considered 
separately. 

Teeth  Suitable  for  the  Bleaching  Operation. — In  deciding  upon  the 
advisability  of  attempting  the  bleaching  operation  in  any  given  case, 
the  general  conditions  which  determine  the  action  of  the  operator  with 
respect  to  all  dental  operations  should  govern  his  course. 

As  most  therapeutic  and  restorative  measures  in  dentistry  are  a 
series  of  compromises  with  disease  conditions  or  their  sequelae,  it  is 
usually  the  duty  of  the  operator  under  the  circumstances  to  capitulate 
upon  the  basis  of  greater  advantage  to  the  patient.  Therefore,  if 
discoloration  of  a  tooth  is  practically  the  onl}^  factor  in  the  problem 
presented  by  a  given  case,  the  effort  should  be  made  to  restore  the 
organ  to  its  normal  condition  of  color.  The  same  rule  should  be  applied 
to  all  cases  of  discolored  teeth  in  which  structural  loss  by  caries  or  frac- 
ture has  not  been  so  great  as  to  preclude  a  satisfactory  restoration  by 
proper  filling  or  replacement  of  the  lost  structure  by  a  porcelain  inlay 
or  other  material.  The  cases  in  which  it  is  not  advisable  to  attempt  a 
bleaching  operation  are  only  those  in  which  loss  of  structure  is  so 
extensive  as  to  require  a  crowning  operation. 

In  the  judgment  of  many  operators  it  is  useless  to  attempt  the  bleach- 
ing of  any  teeth  excepting  the  incisors,  because  of  the  difficulty  and 
length  of  time  frequently  required  for  the  successful  bleaching  of 
cuspids,  bicuspids,  and  molars,  due  to  the  thickness  of  their  walls  and 
the  consequent  depth  of  the  structure  requiring  treatment.  It  is  also 
held  to  be  useless  to  attempt  the  bleaching  of  teeth  which  have  been 
discolored  throughout  their  structure  by  metallic  stains.  The  fallacy 
of  such  a  view  is  self-evident  when  it  is  considered  that  if  any  portion 
of  the  dentinal  structure  of  a  discolored  tooth  is  amenable  to  the 
bleaching  treatment,  its  complete  restoration  is  simply  a  question  of 
continuance  or  repetition  of  the  operation  until  the  desired  end  is 
attained. 

While  teeth  discolored  by  metallic  stains  present  problems  of  great 
complexity  and  require  not  only  special  methods  of  treatment  based 
upon  proper  recognition  of  the  chemical  relationships  involved  between 
the  nature  of  the  stain  and  that  of  the  agent  used  for  its  removal,  in 


474  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

justice  to  the  patient  the  attempt  should  be  made  to  bleach  them,  even 
though  ultimate  failure  results,  in  order  that  the  necessity  for  destruc- 
tion of  the  natural  crown  for  the  purpose  of  its  replacement  by  an 
artificial  substitute  may  be  postponed,  if  possible,  for  as  long  a  period 
as  may  be  attainable. 

Nature  of  the  Problem  Involved  in  Tooth  Bleaching. — The  bleaching 
process  is  dependent  upon  a  chemical  reaction  between  a  compound 
having  color  and  some  substance  capable  of  so  affecting  its  composition 
that  the  color  is  discharged,  or,  in  other  words,  of  so  affecting  the 
integrity  of  the  color  molecule  as  to  destroy  its  identity,  which  results 
in  a  loss  of  its  distinguishing  characteristic,  viz.,  its  color.  For  this 
very  reason,  the  process  of  bleaching  is  extensively  employed  in  the 
industries  to  textile  fibers,  to  straw,  paper  stock,  feathers,  hair,  oils  and 
fats,  etc. 

The  substances  concerned  in  discolor  ation  of  tooth  structure,  as  has 
been  previously  shown,  are  derived  from  the  pulp  and  its  vascular 
elements  and  the  organic  contents  of  the  tubular  structure  of  the 
dentin,  through  the  gradual  putrefactive  processes  which  become  ■ 
operative  subsequent  to  the  death  of  the  pulp.  These  pigmentary 
products  of  pulp  decomposition  we  know  to  be  organic  in  character; 
and  further,  that  they  exhibit  the  property  of  color  by  virtue  of  definite 
conditions  of  molecular  composition — that  is  to  say  a  certain  arrange- 
ment of  a  molecule  having  its  individual  group  of  chemical  and  physical 
properties,  among  which  latter  is  a  characteristic  color.  If  the  surface 
of  a  body  possesses  the  property  of  reflecting  the  combined  spectrum 
of  the  sunlight  without  decomposition,  that  body  is  recognized  upon 
our  retina  as  white.  If,  however,  the  surface  possesses  the  power  of 
neutralizing  a  part  of  the  projected  white  sunlight,  i.  e.,  to  decompose 
it,  and  to  reflect  its  remaining  part,  the  body  will  now  be  recognized  by 
the  retina  as  that  color  which  is  the  characteristic  property  of  the 
predominating  reflected  light  rays,  viz.,  red,  or  green,  or  blue,  etc. 

Whatever  brings  about  an  alteration  in  the  composition  of  a  mole- 
cule at  once  destroys  the  identity  of  the  matter  so  treated.  Hence, 
if  we  can  act  upon  the  coloring  matter  which  gives  rise  to  staining  of  a 
tooth  by  means  of  an  agent  capable  of  effecting  an  alteration  in  the 
atomic  arrangement  of  composition  of  the  color  molecule,  we  may  expect 
incidentally  to  remove  or  discharge  its  color  feature. 

Two  general  classes  of  substances  have  been  used  successfully  as 
bleaching  agents:  first,  those  which  act  by  virtue  of  their  power  to 
evolve  oxygen  in  the  active  or  nascent  condition,  and  known  as  oxidiz- 
ing agents;  second,  those  which  act  in  an  opposite  manner  by  virtue  of 
their  strong  affinity  for  oxygen,  and  which  are  called  reducing  agents. 
The  oxidizing  bleachers  destroy  the  identity  of  the  color  molecule  by 


DISCOLORATION  FROM  DEATH  OF  PULP  475 

seizing  upon  its  hydrogen  element  to  form  water.  The  reducing  agents 
act  by  removing  the  oxygen  atom  from  the  color  molecule  to  form 
by-products  depending  upon  the  character  of  the  reducing  agent  used. 

Chlorin  and  its  congeners  iodin  and  bromin  act  as  indirect  oxidizing 
bleachers;  the  dioxids  of  hydrogen  and  of  sodium  are  direct  oxidizers. 
Potassium  permanganate  may  be  classed  also  with  this  group,  although 
its  successful  use  as  a  bleaching  agent  depends  upon  a  subsequent 
treatment  of  the  substance  to  be  bleached  with  some  solvent  capable 
of  removing  the  manganese  dioxid  formed  as  a  by-product  of  the  action 
of  the  permanganate.  It  has  somewhat  extensive  and  satisfactory 
use  as  an  agent  for  bleaching  sponges,  and  has  been  used  for  bleaching 
teeth,  but  is  of  greatly  inferior  value  to  other  agents  for  the  latter  use. 

The  only  agent  belonging  to  the  group  of  reducing  bleachers  which 
thus  far  has  been  found  available  for  bleaching  teeth  is  sulfur  dioxid, 
either  in  the  gaseous  state  or  in  aqueous  solution. 

Chlorin  as  a  Bleaching  Agent. — The  general  use  of  chlorin  as  a  bleach- 
ing agent  in  the  arts  no  doubt  suggested  its  use  in  the  treatment  of 
tooth  discoloration.  Its  introduction  as  a  tooth-bleaching  agent,  as 
well  as  the  assembling  of  the  general  principles  of  its  use  for  bleaching 
teeth  into  a  coordinated  sj^stem,  was  by  the  late  Dr.  James  Truman, 
whose  method  depends  upon  the  liberation  of  chlorin  from  calcium 
hypochlorite,  commonly  called  bleaching  powder  or  chlorinated  lime, 
in  the  pulp  chamber  and  cavity  of  decay  in  the  tooth.  Chlorin  is 
liberated  from  the  bleaching  powder  by  the  action  of  dilute  acetic  acid. 
When  this  takes  place  in  contact  with  the  discolored  tooth,  it  is  bleached 
rapidly  as  a  result  of  the  action  of  the  chlorin  upon  the  coloring  matter 
contained  in  the  dentinal  tubuli.  Numerous  modifications  of  this 
original  method  of  bleaching  tooth  structure  have  been  suggested,  but, 
as  the  ultimate  result  in  each  is  accomplished  tlirough  the  activity  of 
chlorin,  a  rational  understanding  of  the  mode  of  action  of  chlorin  in  this 
relation  is  of  importance  as  an  aid  to  the  intelligent  use  of  those 
methods  for  the  tooth-bleaching  which  are  dependent  upon,  or  owe 
their  efficacy  to,  that  agent. 

Chlorin  is  an  elementary  gaseous  body,  greenish  in  color,  soluble  in 
water,  having  a  disagreeable  odor,  intensely  irritating  to  the  air 
passages  when  inhaled,  and  poisonous  when  breathed  in  sufficient 
quantity.  It  has  a  strong  affinity  for  all  metallic  bodies,  entering  into 
direct  combination  with  a  number  of  them,  under  favorable  circum- 
stances, with  great  energy — forming,  as  a  rule,  compounds  that  are 
soluble  in  water. 

One  of  the  distinguishing  features,  and  one  which  is  directly  con- 
cerned in  its  use  as  a  bleaching  agent,  is  a  strong  affinity  for  hydrogen. 
So  strong  is  this  affinity,  that  when  a  molecule  of  chlorin  is  brought 


476  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

into  contact  with  a  molecule  of  water  under  favorable  conditions,  the 
hydrogen  of  the  water  molecule  is  seized  upon  by  the  chlorin  to  form 
chlorhydric  acid,  and  the  oxygen  is  set  free  in  the  nascent  state,  a 
condition  under  which  its  oxidizing  powers  are  exhibited  in  their  greatest 
intensity.  This  powerful  affinity  of  chlorin  for  hydrogen  enables  it  to 
decompose  many  other  hydrogen-containing  molecules  in  a  similar 
manner,  forming  chlorhydric  acid  and  destroying  the  identity  of  the 
matter  acted  upon. 

It  has  been  shown  that  all  organic  compounds  which  are  the  products 
of  the  vital  processes  of  the  animal  body  contain  hydrogen  as  an 
important  constituent.  This  applies  also  to  the  decomposition  pro- 
ducts whose  presence  in  the  tubular  structure  of  the  dentin  is  the  cause 
of  tooth  discoloration. 

These  organic  stains  exhibit  the  property  of  color  by  virtue  of  certain 
definite  conditions  of  molecular  composition;  hence,  when  chlorin  acts 
upon  the  coloring  matter  in  the  tooth  by  seizing  upon  and  combining 
with  the  hydrogen  of  the  organic  pigment,  the  identity  of  the  com- 
pound as  such  is  destroyed,  and  its  characteristic  feature,  that  of  color, 
is  lost. 

The  principle  here  outlined  is  involved  in  what  is  termed  the  direct 
action  of  chlorin  in  the  bleaching.  There  is,  however,  another  method 
by  which  chlorin  is  believed  to  act  as  a  bleacher  in  which  its  function  is 
indirect. 

In  some  cases  it  has  been  observed  that  chlorin  fails  to  act  except  in 
the  presence  of  moisture,  and  the  rationale  of  this  is  that  the  bleaching 
under  such  conditions  is  effected  by  nascent  oxygen  liberated  from  the 
water  molecule  when  the  chlorin  combines  with  its  hydrogen  to  form 
hydrochloric  acid;  thus:  CI2  +  H2O  =  2HC1  +  O.  That  such  is  the 
nature  of  the  process  in  many  cases  is  a  reasonable  deduction  from  the 
behavior  of  chlorin  under  analogous  conditions  when  it  acts  indirectly 
as  an  oxidizing  agent. 

Whatever  may  be  the  exact  natiu-e  of  its  ultimate  action,  it  is  to  be 
borne  in  mind  that  the  bleaching  effect  is  due  solely  to  the  alteration 
which  is  made  in  the  composition  of  the  color  molecule  and  that  there 
is  no  solvent  power  whatever  on  the  organic  matter  upon  which  it  acts. 
Chlorin  changes  its  characteristics,  but  does  not  remove  the  molecule 
by  solution.  It  should  be  noted  also,  in  this  connection,  that  the 
chlorin  compounds  of  most  of  the  metallic  elements,  especially  when  in 
dilute  solution,  are  almost  colorless  as  compared  with  many  of  the  other 
metallic  compounds — the  oxids  and  sulfids,  for  example.  Hence  it  is 
that  when  stains  owe  their  color  to  the  presence  of  certain  organic 
compounds  with  some  of  the  metals,  or  even  when  the  coloration  is  due 
to  decomposition  products  of  hemoglobin,  the  color  may  be  discharged 


DISCOLORATION  FROM  DEATH  OF  PULP  477 

readily  by  chlorin;  but  if  the  iron  chlorid  thus  produced  by  the  action 
of  chlorin  on  the  iron  constituent  of  the  hemoglobin  remains  in  the 
tooth  structure,  it  is  gradually  decomposed  and  new  combinations  of  it 
are  to  occur,  which  result  in  a  return  of  the  discoloration. 

All  tooth-bleaching  methods  should  aim  not  only  to  discharge  the 
color  by  suitable  chemical  means,  but  to  remove  all  organic  debris 
and  by-products  of  the  bleaching  process  from  tubuli,  for  as  long  as 
any  remain,  the  tendency  to  a  return  of  the  discoloration  is  always  a 
possible  menace  to  the  permanent  success  of  the  operation.  However, 
care  should  be  exercised  in  the  removal  of  the  organic  constituents  of  the 
tooth  structure  so  as  not  to  weaken  it  unduly. 

When  the  tubular  contents  cannot  be  removed  successfully,  the 
tendency  to  a  return  of  discoloration  may  be  combated  by  hermetically 
sealing  the  tubular  orifices  with  an  impermeable  resinous  varnish  or 
by  permanently  coagulating  them.  This  feature  is  described  more 
fully  in  relation  to  the  details  of  the  bleaching  procedure. 

Preparation  of  the  Tooth  for  the  Operation  of  Bleaching. —  It  is  neces- 
sary to  observe  certain  general  details  in  the  preparation  of  teeth  for 
the  bleaching  operation,  whatever  may  be  the  method  of  treatment 
employed. 

Appropriate  treatment  for  the  removal  of  all  septic  matter  from 
the  pulp  chamber  and  canal,  and  for  the  relief  of  any  existing  conditions 
of  irritation  of  the  pericemental  membrane  and  tissues  of  the  apical 
region,  should  have  been  carried  out  and  the  tooth  brought  to  the 
condition  in  which  permanent  closure  of  the  apical  foramen  of  the  root 
may  be  performed  safely. 

The  rubber  dam  should  be  adjusted  with  si>ecial  care  and  should 
include  only  the  tooth  to  be  bleached.  If  two  adjoining  teeth  are  to 
be  bleached,  both  may  be  isolated  by  the  dam ;  but  in  no  case  should 
one  or  more  adjacent  normal  teeth  be  included  with  the  tooth  to  be 
bleached.  While  the  inclusion  of  teeth  adjacent  to  the  one  which  is 
the  subject  of  any  ordinary  dental  operation  is  in  all  cases  desirable, 
there  are  good  reasons  why  such  a  plan  should  not  be  pursued  in  the 
bleaching  procedure.  The  chemicals  used  for  the  purposes  may 
possibly  have  some  disintegrating  or  solvent  action  upon  the  enamel 
structure  and  such  action,  should  it  occiu-,  should  be  confined  strictly 
to  the  tooth  undergoing  treatment  and  held  within  the  limits  of  safety 
by  close  observation  and  appropriate  treatment,  which  conditions  can- 
not be  controlled  as  thoroughly  and  the  process  managed  as  satisfac- 
torily when  several  teeth  are  included  in  the  field  of  operation. 

Furthermore,  as  nearly  all  of  the  bleaching  agents  used,  or  those 
which  are  employed  as  adjuvants  to  the  process  have  a  more  or  less 
irritative  or  escharotic  effect  upon  the  soft  tissues  of  the  mouth,  extra 


478  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

precautions  must  be  taken  in  adjusting  the  dam  against  leakage  at  its 
attachment  to  the  cervix  of  the  tooth.  For  the  reason  that  the  chances 
of  leakage  are  greatly  multiplied  when  several  holes  are  punched  in  the 
dam  for  adjustment  to  as  many  teeth,  no  other  than  the  tooth  to  be 
treated  should  have  the  dam  adjusted  to  it. 

Supposing  the  tooth  to  be  an  upper  incisor,  the  dam  should  be  slipped 
over  it  and  the  margin  of  rubber  encircling  the  cervix  should  be  carried 
gently  under  the  free  margin  of  the  gum  either  by  means  of  a  small 
flat  burnisher  of  suitable  angle  and  curvature,  or  by  means  of  a  waxed 
floss-silk  thread.  One  or  two  turns  of  a  ligature  should  be  thrown 
around  the  cervix  below  the  dam  to  hold  it  securely  in  place.  The  dam 
may  be  fixed  with  greater  security,  especially  as  against  any  accidental 
traction  made  upon  it  during  the  operation,  by  fastening  it  with  a 
ligature  made  as  follows  and  thrown  around  its  cervix: 

A  piece  of  waxed  ligature  silk  about  eighteen  inches  in  length  has  a 
large  knot  tied  at  about  the  center  by  making  six  or  eight  turns  of  the 
thread  loosely  around  the  end  of  the  index  finger  of  the  left  hand. 


Fig.  402 

Upon  withdrawing  the  finger  there  is  a  series  of  loops  through  which 
one  of  the  free  ends  of  the  thread  is  now  passed,  as  in  making  the  first 
half  of  a  flat  knot,  as  illustrated  in  Fig.  402.  By  drawing  upon  the 
free  ends  of  the  thread  until  all  of  the  loops  are  closed  upon  themselves, 
a  hard  knot  of  more  or  less  spheroidal  shape  is  formed  about  midway 
between  the  ends  of  the  ligature.  The  ligature  so  prepared  is  placed 
around  the  tooth  in  such  a  manner  that  the  knot  as  described  shall  be 
located  at  the  middle  portion  of  the  palatal  cervical  margin.  A  half 
knot  is  then  made  by  tying  the  ligature  in  front  so  that  it  shall  rest 
directly  opposite  the  palatal  knot,  viz.,  at  the  middle  portion  of  the 
labio-cervical  margin.  The  ligature  is  drawn  into  fairly  close  contact 
with  the  tooth,  and,  with  both  ends  held  firmly  in  the  left  hand  and 
drawn  somewhat  tense,  the  portion  encircling  the  tooth  is  firmly  but 
gently  forced  up  against  the  rubber  dam  and  gingival  margin,  the 
ligatm*e  at  the  same  time  being  drawn  tightly  until  the  anatomic 
constriction  of  the  tooth  at  its  cervix  will  serve  to  hold  it  from  slipping 
downward,  especially  upon  the  palatal  aspect  of  the  tooth. 

When  the  ligature  is  found  to  be  securely  placed  as  described,  the 


DISCOLORATION  FROM  DEATH  OF  PULP  479 

knot  upon  the  labial  aspect  is  completed  and  further  enlarged  by  retying 
the  thread  four  or  five  times.  The  free  ends  of  the  ligature  should  be 
cut  off  close  to  the  knot.  As  an  additional  safeguard  against  leakage 
of  irritating  bleaching  agents  through  the  cervical  attachment  of  the 
dam  upon  the  soft  tissues,  it  is  well,  after  making  the  tooth  perfectly 
dry,  to  paint  the  ligatiu-e  and  a  narrow  band  of  its  adjacent  territory 
with  chloropercha,  which,  after  evaporation  of  the  solvent,  will  effectu- 
ally prevent  any  accident  from  leakage.  No  clamps  must  be  used,  as 
chlorin  acts  directly  upon  the  steel  forming  soluble  salts. 

The  placing  of  a  large  knot  upon  the  palatal  aspect  at  the  cervical 
margin  has  another  decided  advantage  in  that  it  not  only  holds  the 
dam  more  secm-ely  against  slipping  downward,  but  holds  it  away 
from  the  palatal  sm-face  which  is  ordinarily  the  point  of  entrance  to 
the  pulp  chamber  and  canals  in  these  cases.  The  point  of  canal 
entrance,  however,  may  be  through  a  proximate  cavity,  if  such  a  one 
affords  sufficient  access. 

The  canal  filling  in  all  cases  of  bleaching,  without  exception,  should 
be  gutta-percha.  Xo  other  material  used  for  canal  filling  possesses 
the  generally  desirable  qualities  needed  for  that  purpose  in  this  class  of 
cases.  The  extent  of  the  canal  filling  should  include  one-third  or  not 
over  one-half  of  the  distance  from  the  apex.  A  considerable  portion 
of  the  canal  beyond  the  level  of  the  gingival  margin  is  thus  left  unfilled 
in  order  that  the  coronal  end  of  the  root  may  be  bleached  as  well  as  the 
tooth  crowTi.  This  is  especially  necessary  when  more  or  less  recession 
of  the  gum  from  its  normal  attachment  has  occurred,  leaving  the 
cervical  cementum  exposed  to  the  action  of  the  oral  fiuids,  food,  etc., 
which  have  a  tendency  to  cause  discoloration  of  the  exposed  root 
tissue. 

The  root  being  filled  as  directed,  all  fillings  wherever  existent  in  the 
tooth  should  be  removed.  This  is  a  preliminary  procedm*e  which 
should  not  be  omitted  in  any  case,  but  where  any  bleaching  method  is 
used  which  invoh'es  the  employment  of  chlorin  as  the  active  agent  it 
becomes  necessary  for  reasons  which  are  explained  in  connection  with 
the  description  of  the  chlorin  methods.  Aside  from  other  considera- 
tions, the  removal  of  all  fillings  preparatory  to  the  bleaching  operation 
has  a  decided  value  in  facilitating  the  process  by  exposing  an  increased 
area  of  dentinal  structure  and  thereby  permitting  the  action  of  the 
bleaching  agent  over  a  larger  territory  of  ingress. 

When  all  fillings  or  softened  tooth  structure  have  been  removed  by 
mechanical  process,  as  well  as  all  septic  and  extraneous  matter  of 
w^hatever  character,  the  tooth  should  be  washed  thoroughly  with 
dilute  ammonia  water,  or  better,  with  a  hot  saturated  solution  of  borax 
in  distilled  water.     The  object  of  this  treatment  is  to  remove  by 


480  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

saponification  and  solution  all  fatty  matters  which  may  obstruct  the 
ingress  of  the  bleaching  agent  into  the  dentinal  structure. 

In  nearly  all  cases  where  discoloration  has  occurred  from  a  decom- 
posed pulp,  and  where  the  canals  and  pulp  chamber  have  been  left 
untreated,  there  will  be  observed,  on  opening  into  such  a  pulp  chamber 
for  the  first  time,  a  dark  layer  of  oily  or  greasy  material  lining  its  walls. 
The  thorough  removal  of  this  dark  layer  should  be  effected  prior  to 
any  attempt  at  bleaching,  as  it  appears  to  prevent  the  ingress  of  the 
bleaching  agent  into  the  dentinal  structure.  The  most  satisfactory 
method  for  removing  the  dark  greasy  layer  is  by  the  use  of  suitable 
instruments — either  properly  shaped  spoon  or  hoe  excavators  or  round 
burs  in  the  engine.  The  thorough  removal  of  this  layer  necessitates 
free  access  to  the  pulp  chamber,  which,  as  a  general  rule,  should  be 
obtained  by  means  of  an  ample  opening  upon  the  lingual  aspect  of  the 
tooth,  in  the  case  of  incisors,  and  through  the  morsal  surface  in 
bicuspids,  etc. 

After  he  has  effected  a  thorough  cleansing  of  the  tooth  by  mechanical 
means  and  through  the  agency  of  borax  or  ammonia  and  hot  distilled, 
water,  the  operator  should  dry  it  to  the  extent  of  removing  all  super- 
'  fluous  moisture.  Then  the  tooth  will  be  in  condition  for  the  applica- 
tion of  whatever  method  of  bleaching  may  be  chosen  for  the  particular 
case  in  hand.  When  sodium  dioxid  or  Schreier's  kalium-natrium  with 
hydrogen  dioxid  is  to  be  used  as  the  bleaching  agent,  the  preliminary 
saponification  of  the  canal  contents  with  ammonia  or  hot  borax  solution 
becomes  unnecessary. 

Truman's  Method. — ^This,  as  before  stated,  was  the  first  method 
successfully  employed  for  bleaching  teeth.  It  consists  of  liberating 
chlorin  from  ordinary  chlorinated  lime  by  means  of  a  weak  acid  in  the 
pulp  chamber  of  the  tooth.  Any  acid  will  effect  the  liberation  of 
chlorin  from  the  bleaching  powder,  but  acetic,  tartaric,  or  oxalic  acids 
are  generally  used.  Care  must  be  observed  in  selecting  a  good  quality 
of  bleaching  powder,  as  that  substance  rapidly  undergoes  spontaneous 
decomposition,  especially  in  a  moist  atmosphere.  Good  chlorinated 
lime  is  a  dry  powder  having  a  strong  odor  of  chlorin  which  should  con- 
tain not  less  than  35  available  per  cents.  If  it  is  moist  or  pasty,  and 
has  but  a  feeble  odor,  it  should  be  rejected  as  worthless.  Brands  of 
bleaching  powder  dispensed  in  metallic  packages  should  not  be  used, 
as  they  are  invariably  contaminated  with  metallic  chlorids  due  to  the 
slow  action  of  the  contents  upon  the  container.  The  return  of  dis- 
coloration in  many  cases  after  bleaching  by  the  Truman  method  is 
undoubtedly  due  to  the  use  of  bleaching  powder  so  contammated. 
The  powder  dispensed  in  glass  bottles  or  in  paraffined  paper  cartons  is 
more  reliable. 


DISCOLORATION  FROM  DEATH  OF  PULP  481 

Its  application  to  the  tooth  may  be  effected  in  several  ways: 

(a)  By  packing  the  dry  powder  in  the  pulp  chamber  and  then 
moistening  the  latter  with  the  acid. 

(b)  By  mixing  the  powder  with  sufficient  distilled  water  to  make  a 
coherent  mass  which  is  more  easily  manipulated,  then  packing  it  in 
the  pulp  chamber  and  applying  the  acid. 

(c)  By  first  moistening  the  interior  of  the  tooth  with  the  acid,  next 
dipping  the  instrument  into  the  powder  and  then  into  the  acid,  each 
time  carrying  the  mixed  materials  into  the  tooth  until  the  desired 
change  of  color  is  produced. 

Probably  the  most  satisfactory  method  is  to  pack  the  dry  powder 
into  the  tooth  and  apply  the  acid  to  it,  after  which  immediately  seal 
the  cavity  with  a  single  pellet  of  gutta-percha.  By  using  a  50  per  cent, 
solution  of  acetic  acid  the  evolution  of  chlorin  will  take  place  with  a 
satisfactory  degree  of  uniformity,  and  not  so  rapidly  as  to  interfere 
with  its  penetration  throughout  the  discolored  tubular  structure  of  the 
dentin.  The  bleaching  mass  may  be  sealed  in  place  by  means  of  zinc 
oxyphosphate  if  desired,  but  it  is  usually  unnecessary  to  use  anything 
other  than  gutta-percha  or  one  of  the  soft  temporary  stopping  materials 
for  the  pm'pose. 

The  case  may  be  dismissed  for  one  or  two  days  and  the  treatment  as 
outlined  repeated  at  similar  intervals  until  the  tooth  is  restored  to 
normal  color. 

The  instruments  used  in  connection  with  this  process  should  be  of 
vulcanite,  bone,  ivory  or  wood.  Under  no  consideration  should  steel, 
gold,  or  platinum  instruments  be  used,  as  chlorin  acts  directly  upon 
each  of  these  metals,  forming  soluble  chlorids,  which,  if  carried  into  the 
tooth  structure,  will  give  rise  to  a  permanent  staining  of  most  intract- 
able character.  The  only  metals  which  may  be  used  safely  in  connec- 
tion with  any  chlorin  process  of  bleaching  are  zinc  and  aluminum,  the 
chlorids  of  which  are  colorless,  but,  nevertheless,  they  are  objectionable 
for  the  reason  that  both  are  coagulant  and  color  mordants.  Aluminum 
instruments  for  the  purpose  may  be  improvised  quickly  out  of  wire  or 
heavy  plate.  Gold  instruments  have  been  recommended  but  they  are 
open  to  the  very  grave  objection  of  forming  a  chlorid  by  direct  combina- 
tion with  chlorin,  which  salt  is  one  of  the  most  important  staining  media 
known  to  the  histologist;  as  a  matter  of  fact,  the  author  has  seen  several 
cases  where  a  permanent  purple  staining  of  the  tooth  has  resulted 
from  neglect  to  remove  gold  fillings  before  applying  the  chlorin 
method  of  bleaching,  and  there  is  certainly  no  reason  why  the  same 
result  should  not  follow  the  using  of  gold  instruments  in  the  same 
connection. 

It  is  good  practice  to  bleach  the  discolored  tooth  a  shade  or  two 
31 


482  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

lighter  than  its  mate,  as  a  bleached  tooth  usually  darkens  slightly  in  a 
short  time. 

When  the  tooth  has  been  restored  to  its  proper  color  it  should  be 
washed  thoroughly  with  liberal  quantities  of  very  hot  distilled  water, 
dried  out  with  bibulous  paper,  and  thoroughly  desiccated  with  a 
current  of  dry  hot  air,  after  which  the  canals,  pulp  chambers,  and 
cavities  should  be  filled  with  zinc  oxychlorid. 

The  final  filling  of  the  cavities  of  entrance  and  of  decay  should  be 
postponed  until,  by  a  lapse  of  considerable  time,  the  permanence  of 
the  operation  has  been  established.  This  probationary  period  may  be 
prolonged  to  four  or  six  months  with  advantage. 

The  final  washing  of  the  tooth  with  hot  distilled  water  previous  to 
the  insertion  of  the  zinc  oxychlorid  filling  is  a  feature  of  the  operation 
which  requires  special  care  and  attention.  As  left  after  the  application* 
of  the  bleaching  agent,  the  pulp  chamber  and  canals  and  dentinal 
structure  are  filled  with  free  chlorin  in  solution,  iron  chlorid  from  the 
combination  of  the  chlorin  with  the  iron  element  of  the  color  molecule, 
calcium  acetate,  or  other  salt  of  calcium,  depending  upon  the  nature 
of  the  acid  used  in  the  process  and  probably  some  undecomposed 
bleaching  powder.  These  substances  should  be  removed  thoroughly 
by  the  hot  water  douche.  At  least  a  pint  of  water  should  be  injected 
strongly  into  the  interior  of  the  tooth  by  means  of  a  large  bulb  sj^ringe 
or  other  convenient  means,  before  the  dam  is  removed.  A  thick  towel 
or  a  suitable  basin  held  in  close  proximity  to  the  tooth  will  catch  the 
water  as  it  returns  from  the  tooth  and  protect  the  clothing  of  the 
patient.  Distilled  water  should  be  used  in  all  cases  for  this  iirigating 
douche,  as  river  water  and  many  other  specimens  of  water  from  natural 
sources  contain  iron  in  solution,  which  could  readily  become  a  con- 
taminating factor,  leading  to  subsequent  return  of  discoloration. 

Zinc  oxychlorid  is  selected  as  the  permanent  filling  for  the  pulp 
chamber,  for  the  reason  that  it  is  necessary  so  to  act  upon  the  bleached 
organic  residuum  in  the  tubular  structure  as  to  prevent  any  alteration 
of  its  character,  which  may  result  in  the  production  of  a  subsequent 
coloration. 

Zinc  chlorid  possesses  the  property  of  converting  many  organic 
substances  into  unalterable  compounds  by  its  coagulant  action,  thus 
tanning  or  mummifying  animal  tissue  and  preserving  it  indefinitely. 
A  mass  of  zinc  oxychlorid,  before  it  sets,  that  is,  before  chemical  com- 
bination takes  place  between  the  zinc  oxid  powder  and  the  zinc  chlorid 
liquid  is  functionally  free  zinc  chlorid,  and,  as  a  matter  of  fact,  the 
properties  of  zinc  chlorid  are  manifested  by  such  a  mass  for  a  con- 
siderable period  of  time  after  the  mass  has  apparently  set.  When 
introduced  into  the  pulp  chamber  and  canal,  its  action  upon  the  organic 


DISCOLORATION  FROM  DEATH  OF  PULP  483 

debris  in  the  tubuli  is  as  stated,  and  the  material,  if  the  operation  has 
been  performed  successfully,  is  effectually  prevented  from  further 
alteration,  upon  which  condition  the  permanence  of  the  operation 
depends. 

Another  method  for  preventing  subsequent  alteration  of  the  bleached 
organic  debris  in  the  tubular  structiue  is  to  desiccate  the  tooth  thor- 
oughly by  means  of  the  hot  air  blast  and  saturate  the  dentin  with  some 
insoluble  resinous  varnish,  such  as  copal  ether  varnish,  or,  still  better, 
the  solution  of  trinitrocellulose  in  methyl  alcohol  and  amyl  acetate, 
known  in  commerce  as  ''kristaline,"  or  in  the  market  as  "cavitine." 
The  pulp  chamber  and  canals  may  then  be  filled  with  any  suitable 
filling. 

As  between  the  zinc  oxychlorid  filling  and  the  varnish  lining,  the 
choice  in  general  should  be  of  the  former.  The  varnish  lining  is  adapt- 
able to  cases  of  long  standing,  where  complete  liquefaction  of  the 
tubular  contents  had  left  them  practically  empty,  and  where,  as  a 
consequence,  there  is  nothing  upon  which  zinc  chlorid  can  exert  its 
coagulating  effect. 

Other  Chlorid  Methods. — The  solution  of  chlorinated  soda  known  as 
Labarraque's  solution,  or  liquor  sodse  chloratse  U.  S.  P.,  may  be 
applied  to  the  previously  desiccated  tooth  structiue  until  the  dentin 
is  saturated  with  the  solution,  after  which  an  application  of  a  dilute 
acid  which  liberates  chlorin  is  made.  The  chemical  principles  involved 
are  analogous  to  those  upon  which  the  methods  with  bleaching  powder 
depend,  the  only  difference  being  that  the  source  of  the  active  agent, 
chlorin,  is  in  one  case  its  calcium  compound,  which  is  a  dry  powder, 
and  in  the  other  the  analogous  soluble  sodium  compound. 

The  precautions  necessary  to  be  observed  are  exactly  the  same  as 
those  required  in  Truman's  method,  already  described.  The  results 
obtained  by  this  process  are  not  as  thorough  nor  as  satisfactory  as  by 
the  Truman  method. 

Chlorin  per  se  has  been  used  for  tooth  bleaching,  and  was  the  basis  of 
a  method  devised  by  Dr.  E.  P.  Wright  of  Richmond,  Virginia.  This 
involved  the  use  of  a  complicated  apparatus  by  which  a  continuous 
jet  of  chlorin  was  thrown  into  and  about  the  tooth.  The  complexity 
of  the  apparatus  was  a  formidable  obstacle  to  the  general  use  of  the 
method  and  it  was  abandoned,  though  the  results  were  in  many  cases 
very  satisfactory. 

lodin. — Reference  has  been  made  previously  to  iodin  as  a  bleaching 
agent.  Its  chemical  action  is  nearly  analogous  to  that  of  chlorin, 
though  less  energetic.  In  slight  discolorations,  however,  iodin  often 
may  be  used  to  considerable  advantage  by  simply  satm^ating  the 
dentin  with  an  alcohol  solution  of    iodin,    viz.,    the    official    7    per 


484  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

cent,  tincture,  until  the  tooth  structure  is  stained  a  characteristic 
yellow.  Then  the  cavity  is  sealed  temporarily  with  a  gutta-percha 
filling  and  the  case  dismissed  for  twenty-four  hours,  at  the  expiration 
of  which  period  a  marked  improvement  in  color  will  be  observed. 
The  same  precaution  is  necessary  in  the  use  of  iodin  for  bleaching 
purposes  as  with  the  use  of  chlorin  in  regard  to  the  removal  of  metallic 
fillings  and  the  avoidance  of  contact  with  metallic  instruments. 

Bleaching  by  Means  of  the  Dioxid  of  Hydrogen  and  of  Sodium. — ^The 
commercial  introduction  of  solutions  of  hydrogen  dioxid  marked  a 
new  era  in  the  operation  of  bleaching  discolored  teeth.  The  bleaching 
property  of  hydrogen  dioxid  has  been  known  to  chemists  for  many 
years,  but  the  application  of  this  property  to  tooth  bleaching  dates 
from  the  medicinal  use  of  hydrogen  dioxid  solutions  for  the  treatment 
of  purulent  conditions  of  the  pulp  canal  and  about  the  roots  of  teeth. 
When  applied  in  the  canals  of  discolored  and  infected  teeth,  it  was 
observed  that  a  noticeable  bleaching  of  the  discolored  structure  resulted. 
The  hint  thus  given  was  further  studied  until  it  was  found  that  under 
proper  conditions  the  whole  structiue  of  a  discolored  tooth  Imight^be 
restored  successfully  to  normal  color. 

Nascent  oxygen  may  be  furnished  by  two  kinds  of  auto-oxidizers — 
one  direct  source  is  its  allotropic  form  known  as  ozone,  and  the  other 
is  represented  by  the  many  dioxids,  chiefly  hydrogen  dioxid,  and  those 
of  the  alkali  and  alkaline  earth  metals.  The  nascent  oxygen  obtained 
from  both  sources  is  based  on  the  same  principle  of  formation. 
Ozone  =  0—0—0,  or  O3,  is  split  up  in  O2O  (nascent  state). 

A  dioxid,  X— O— O,  or  XO2,  is  split  up  inXO— O  (nascent  state). 

According  to  Nernst,  the  formation  and  the  association  of  ozone  are 
illustrated  by  the  following  equation: 

03^02+0 

02  7!;o  +0 

Only  one  of  the  three  atoms  of  the  ozone  molecule  enters  into  active 
or  atomic  oxygen,  the  other  two  forming  molecular  or  inactive  oxygen. 
This  is  true  of  the  oxygen  molecule  of  a  dioxid,  one  atom  is  set  free 
while  the  other  one  remains  combined  with  the  metal  in  the  form  of  an 
oxid.  The  ozone  molecule  and  the  dioxid  molecule  play  the  role  of  a 
single  atom  of  oxygen  in  the  reaction  of  oxidation.  The  amount  of 
available  oxygen  in  a  dioxid  depends  on  the  degree  of  superoxidation  of 
the  original  oxid.  Ozone,  as  well  as  the]^dioxids,  are  endothermic 
compounds,  that  is,  they  require  energy  in  the  form  of  heat  or  electricity 
for  their  formation.  They  are  comparatively  easily  decomposed, 
liberating  again  the  same  amount  of  energy  in  the  form  of  heat  which 
was  absorbed  in  their  formation.     Ozone  has,  thus  far,  been  produced 


DISCOLORATION  FROM  DEATH  OF  PULP  485 

only  as  a  gas,  while  the  dioxids,  with  the  exception  of  hydrogen  dioxid, 
are  solids.  Oxygen  obtained  from  ozone  is  usually  produced  by  electric 
energy  at  the  place  of  its  consumption ;  it  is  an  unstable  gas  which,  for 
practical  purposes,  cannot  well  be  stored.  The  dioxids  are  usually 
fairly  stable  compounds;  they  furnish  any  fixed  amount  of  oxygen,  if 
so  desired,  at  any  moment  and  are  in  reality  transportable  accumulators 
of  available  oxygen.  Atomic  oxygen — oxygen  in  its  nascent  state — 
has  a  free  valency;  it  cannot  remain  in  that  state,  but  energetically 
seeks  to  combine  with  organic  matter.  This  powerful  affinity  for  every 
oxidizable  substance,  including  albumin,  is  known  as  oxidation,  or 
when  accompanied  by  heat  and  light,  as  combustion. 

The  earlier  dioxid  preparations  were  found  to  be  lacking  in  strength; 
aqueous  solutions  containing  more  than  3  or  4  per  cent,  of  absolute 
hydrogen  dioxid  were  found  to  be  too  unstable  to  keep  for  any  length 
of  time,  and  hence  were  unreliable.  The  problem  of  securing  a  stable 
high  percentage  solution  of  the  dioxid  was  solved  by  using  ether  as  a 
menstruum. 

Subsequent  to  the  introduction  of  the  pyrozone  preparations,  the 
firm  of  Merck  has  produced  a  100-volume  solution  of  hydrogen 
dioxid  under  the  trade  name  of  perhydrol,  which  is  the  most  active 
and  efficient  of  the  hydrogen  dioxid  preparations  as  tooth  bleaching 
agents.  Aside  from  the  ordinary  3  per  cent  solution  of  hydrogen 
dioxid,  higher  concentrated  solutions  are  found  on  the  market.  A  25 
per  cent,  solution  of  hydrogen  dioxid  in  ether  is  known  as  caustic 
pyrozone,  and  a  30  per  cent,  solution  in  water  is  known  as  perhydrol, 
or  as  peraquin.  Caustic  pyrozone  is  put  up  in  glass  tubes  containing 
a  few  cubic  centimeters,  while  perhydrol  is  marketed  in  paraffin-lined 
bottles  of  various  sizes.  In  opening  a  pyrozone  tube,  great  care  should 
be  exercised  to  prevent  explosion  by  placing  the  tube  in  cold  water 
and  wrapping  it  in  a  wet  towel  before  the  end  is  broken  off.  Its  con- 
tents must  be  transferred  at  once  to  a  glass-stoppered  bottle,  provided 
with  a  ground  cap,  to  prevent  evaporation  of  the  ether.  Perhydrol 
solution  is  to  be  greatly  preferred  whenever  a  highly  concentrated 
solution  of  hydrogen  is  desired.  It  is  a  chemically  pure  solution  of 
H2O2  in  distilled  water,  furnishing  about  30  per  cent,  by  weight  or 
100  per  cent,  by  volume  of  available  oxygen.  It  is  absolutely  free  from 
acid,  and  may  be  diluted  with  water  or  alcohol  to  any  desired  strength. 
Solutions  should  be  made  fresh  as  needed.  If  carefully  preserved  in 
the  original  container  and  stored  in  a  cool  place  perhydrol  will  retain 
its  oxygen  for  some  time.  Very  recently,  hydrogen  dioxid  in  dry  form, 
known  as  perhydrit,  has  been  placed  on  the  market.  Perhydrit  is  a 
compound  of  hydrogen  dioxid  and  urea,  containing  about  30  to  35 
per  cent,  of  available  hydrogen  dioxid.     It  is  a  very  unstable  compound. 


486  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

Any  soluble  dioxid  compound  intended  for  bleaching  purposes  should 
be  tested  for  its  oxygen  content.  A  simple  test  is  made  as  follows: 
mix  ten  cubic  centimeters  of  distilled  water  with  ten  drops  of  dilute 
sulphuric  acid,  one  drop  of  potassium  chromate  test-solution  (one  part 
potassium  chromate  dissolved  in  sufficient  water  to  make  one  hundred 
cubic  centimeters),  and  two  cubic  centimeters  of  ether.  On  the 
addition  of  the  solution  containing  hydrogen  dioxid,  a  blue  color  will 
appear  at  the  line  of  contact  which  will,  after  shaking,  separate  with  the 
ethereal  layer. 

Hydrogen  dioxid,  H2O2,  belongs  to  the  class  of  oxidizing  bleachers, 
and  owes  its  activity  in  this  respect  to  the  weak  state  of  chemical 
combination  in  which  one  of  its  atoms  of  oxygen  is  bound  to  the  water 
molecule.  Many  substances  serve  to  disrupt  the  compound  and 
liberate  one  of  its  oxygen  atoms.  In  contact  with  pus,  blood,  inspis- 
sated mucus,  albumin,  and  in  fact,  almost  every  kind  of  organic 
matter,  its  decomposition  takes  place,  liberating  oxygen  and  decompos- 
ing the  organic  matter  either  wholly  or  in  part.  Hydrogen  dioxid  does 
not  bleach  all  of  the  decomposition  products  of  hemoglobin  with  equal 
facility.  It  quickly  removes  the  pink  discoloration  following  the  initial 
extravasation  of  hemoglobin  into  the  dentin,  but  when  the  brown  stage 
has  been  reached,  indicative  of  the  formation  of  hematin,  its  action  is 
but  slight.  Later,  however,  it  bleaches  more  readily.  The  refractory 
nature  of  hematin  with  respect  to  hydrogen  dioxid  has  been  tested 
experimentally  upon  the  substance  out  of  the  mouth. 

It  is  important  to  note  that  all  acids  promptly  convert  hemoglobin 
into  hematin,  which  is  highly  resistant  to  the  action  of  hydrogen  dioxid; 
therefore,  whenever  hydrogen  dioxid  is  used  to  bleach  a  tooth  in  the 
primary  or  pivot  stage  of  discoloration  the  hydrogen  dioxid  should  be 
made  alkaline  with  sodium  carbonate  or  hydroxid  to  neutralize  at  least 
its  usual  slight  acidity,  otherwise  its  acid  content  will  act  upon  the 
hemoglobin,  converting  it  into  hematin,  and  thus  set  the  color  in  such 
a  way  as  to  be  invulnerable  to  the  action  of  the  hydrogen  dioxid. 

In  bleaching  discolored  teeth  with  hydrogen  dioxid,  perhydrol  or 
the  ethereal  25  per  cent,  solution  known  as  pyrozone  is  applied 
directly  to  the  internal  portions  of  the  tooth  upon  small  pledgets  of  cot- 
ton or  cotton  wisps  rolled  upon  a  fine  flexible  canal  instrument.  After 
each  application  the  menstruum  is  evaporated  by  blasts  of  warmed 
air  from  a  hot  air  syringe,  and  the  applications  similarly  made  are 
repeated  until  the  desired  effect  is  produced.  It  has  been  found  in 
practice  that  more  rapid  and  permanent  effects  are  produced  when  the 
solution  is  rendered  alkaline.  This  may  be  done  readily  by  the 
addition  of  a  few  drops  of  liquor  ammonise  fortior  or  by  a  solution  of 
one  of  the  caustic  alkalies,  namely,  sodium  or  potassium  hydroxid  or 


DISCOLORATION  FROM  DEATH  OF  PULP  487 

sodium  dioxid.  A  very  satisfactory  method  of  securing  the  alkahue 
effect  in  this  process  is  that  suggested  by  Dr.  D.  N.  McQuillan.  His 
method  is  to  treat  first  the  pulp  chamber  and  canals  with  applications 
of  Schreier's  kalium-natrium  preparation  and  after  the  debris  from  its 
action  has  been  mechanically  removed  with  instruments  and  cotton 
twists,  without  washing  the  canal,  an  application  of  pyrozone  is  made. 
The  bleaching  action  follows  with  great  rapidity,  and  has  apparently 
greater  permanence  than  when  the  pyrozone  is  used  alone.  In  cases 
in  which  the  action  proceeds  very  slowly,  for  example,  when  at  the  end 
of  a  thirty  minutes'  continuous  treatment  the  bleaching  is  not  complete, 
it  is  well  to  seal  an  application  of  pyrozone  upon  cotton  in  the  canal 
and  allow  it  to  remain  for  twenty-four  hours,  when  a  second  treatment 
will  usually  complete  the  operation. 

In  this,  as  in  all  bleaching  operations,  it  is  advisable  to  fill  the  tooth 
temporarily  with  some  filling  which  may  be  easily  removed  m  order  to 
test  the  permanence  of  the  operation,  and  after  the  lapse  of  a  reasonable 
time,  if  there  is  no  tendency  to  a  return  of  the  discoloration,  the  canals 
and  cavity  may  be  filled  permanently. 

Harlan's  method  consists  in  acting  upon  hydrogen  dioxid  by  alumi- 
num chlorid.  The  aluminum  salt  is  packed  in  the  cavity  and  moistened 
with  the  dioxid.  Experimental  study  of  the  reaction  between  alumi- 
num chlorid  and  hydrogen  dioxid  by  Dr.  E.G.  Kirk  developed  the  fact 
that  oxygen  and  no  chlorin  was  given  off,  and  that  the  aluminum 
chlorid  was  unaltered  during  the  process.  Hence  it  was  discovered  that 
the  reaction  was  due  simply  to  a  catalytic  action  of  the  aluminum  salt 
(a  property  which  in  this  relation  it  shares  in  common  with  many  other 
metallic  salts,  whereby  nascent  oxygen  is  liberated  from  the  hydrogen 
dioxid.  The  process,  therefore,  has  no  greater  value  than  those  in 
which  hydrogen  dioxid  is  applied  directly. 

The  Sodium  Dioxid  Method. — Sodium  dioxid,  Na202,  is  the  chemical 
analogue  of  hydrogen  dioxid,  and  like  the  latter  is  characterized  by  the 
readiness  with  which  it  parts  with  its  atom  of  loosely  combined  oxygen 
under  similar  circumstances.  The  essential  difference  in  its  properties 
is  the  character  of  its  by-product  after  its  decomposition  has  taken 
place.  Being  a  strong  caustic  alkali,  sodium  dioxid  still  retains  its 
alkaline  and  caustic  properties  after  the  loss  of  one  of  its  atoms  of 
oxygen,  becoming  Na20,  which  in  combination  with  water  is  ordinary 
sodium  hydroxid  or  caustic  soda.  This  substance,  as  well  as  the 
sodium  dioxid,  has  not  only  a  saponifying  property  for  all  of  the  vege- 
table and  animal  oils  and  fats,  but  also  a  solvent  action  upon  animal 
tissue.  This  property  is  of  great  value  in  removing  from  the  dentin 
structure  all  of  the  contained  organic  matter,  whether  normal  or  in  a 
state  of  decomposition.     Having  the  oxidizing  and  consequently  the 


488  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

bleaching  quality  in  addition  to  its  solvent  and  saponifying  properties, 
it  is,  therefore,  one  of  the  most  valuable  bleaching  and  detergent  agents 
at  our  command.  The  substance  is  dispensed  as  a  yellowish-white 
powder  in  tin  cans  or  glass  bottles  hermetically  sealed,  as  it  is  very 
hygroscopic,  and  after  twenty-four  hours'  exposure  to  moist  air  absorbs 
nearly  its  own  weight  of  water;  it  also  loses  much  of  its  activity. 

For  use  as  a  bleaching  agent,  it  is  always  applied  to  the  dentin  in 
saturated  solution,  and  never  in  the  solid.  In  making  the  solution 
special  care  is  necessary  in  order  to  avoid  raising  of  temperature,  by 
reason  of  the  energy  with  which  it  enters  into  combination  with  the 
water.  If  the  solution  is  allowed  to  become  heated  in  the  making, 
decomposition  of  the  compound  with  loss  of  oxygen  occurs,  and  its 
bleaching  power  is  destroyed.  The  solution  is  best  made  by  pouring 
into  a  small  beaker,  of  1  ounce  capacity,  about  2  drams  of  distilled 
water,  and  immersing  the  beaker  in  a  larger  vessel  or  dish  containing 
iced  water  or  pounded  ice.  The  can  containing  the  dioxid  powder 
should  then  have  its  lid  perforated  with  a  number  of  small  holes 
similar  to  the  lid  of  a  pepper  shaker,  and  the  powder  should  be  dusted 
slowly  into  the  distilled  water  in  the  small  beaker;  or  the  powder  may 
be  dropped  gradually  into  the  water  by  tapping  it  from  the  point  of  a 
knife  or  spatula.  The  powdbr  is  added  to  the  water  until  the  solution 
assumes  a  semi-opaque  appearance,  indicating  the  point  of  saturation. 

On  removing  the  beaker  from  the  cooling  mixture,  the  dioxid  solution 
in  a  few  minutes  will  assume  a  transparent,  straw-colored  appearance 
and  is  ready  for  use. 

The  applications  are  to  be  made  similarly  to  those  of  hydrogen 
dioxid,  but  upon  asbestos  fiber  instead  of  cotton,  as  the  latter  is  acted 
upon  by  the  sodium  dioxid  and  converted  into  a  glue-like  material, 
which  is  difficult  to  remove  and  which  interferes  with  the  success  of  the 
operation. 

After  the  dentin,  which  should  have  been  desiccated  previously,  is 
thoroughly  saturated  with  the  dioxid  solution,  an  application  of 
10  per  cent,  sulfuric  acid  should  be  made,  which  neutralizes  the 
strong  alkali,  forming  sodium  sulfate  and  hydrogen  dioxid,  thus : 

Na202  +  H2SO4  =  Na2S04  +  H2O2. 

The  reaction  is  usually  attended  with  some  effervescence  which, 
taking  place  in  the  tubular  structure  of  the  dentin,  mechanically  forces 
out  its  contents  and  thus  exerts  a  detergent  action  upon  it.  The  tooth 
should  now  be  washed  with  hot  distilled  water  in  copious  quantity  and 
the  dioxid  application  repeated,  omitting  the  subsequent  treatment 
with  acid,  but  washing  again  thoroughly  with  the  hot  water. 

Sodium  dioxid  solution,  as  prepared  for  bleaching,  may  be  applied 


DISCOLORATION  FROM  DEATH  OF  PULP  489 

to  the  pulp  chamber  and  root  canal  without  the  preliminary  treatment 
required  where  other  bleaching  agents  are  employed.  It  is  without 
harmful  irritative  action  upon  the  apical  tissues  unless  used  in  excess 
or  forced  through  the  foramen  by  careless  manipulation.  It  is  a  power- 
ful germicide  and  disinfectant,  and  therefore  peculiarly  suited  to  the 
treatment  of  putrescent  cases,  which,  by  its  action,  are  rendered  sterile 
and  aseptic  as  well  as  bleached  at  one  operation.  Its  saponifying  and . 
solvent  properties  remove  completely  the  greasy  dark  layer  of  decom- 
posed material  which  is  found  lining  the  pulp  chamber  and  canals, 
alluded  to  previously,  so  that  the  use  of  the  sodium  dioxid  method 
makes  unnecessary  the  preliminary  application  of  borax  or  ammonia 
for  its  removal.  When  sodium  dioxid  is  used  for  its  sterilizing  property, 
the  foramen  should  be  allowed  to  remain  unsealed  until  after  the 
bleaching  operation  has  been  completed.  It  happens  sometimes  that 
the  improvement  in  color  following  the  application  of  the  dioxid 
methods  is  only  partial,  and  the  result  falls  short  of  restoration  to 
normal ;  or,  in  other  words,  the  bleaching  reaches  a  certain  point  beyond 
which  the  color  resists  the  further  action  of  the  bleaching  agent.  In 
such  cases  the  decomposition  of  the  color  molecule  has  probably 
resulted  in  the  formation  of  iron  oxid  as  an  end-product.  In  practice 
this  residual  discoloration  can  be  removed  generally  by  treatment 
with  oxalic  acid.  A  small  crystal  is  to  be  sealed  in  the  moist  pulp 
chamber  for  twenty-four  hours,  and  afterward  washed  out  with  a 
copious  irrigation  of  hot  distilled  water. 

The  sodium  dioxid  method  removes  the  tubular  contents  more 
completely  than  any  other  method,  and  the  result  is  unique  from  the 
fact  that  not  only  is  the  tooth  restored  to  normal  color,  but  to  normal 
translucency;  the  opaque  white  effect  resulting  from  other  methods 
of  bleaching  is  due  to  the  bleached  organic  debris  remaining  in  the 
tubuli,  but  by  the  solvent  action  of  the  strong  caustic  alkali  this  is 
removed.  The  final  treatment  of  the  tooth  is  the  same  in  this  as  in 
other  methods,  though  the  dentin  should  be  desiccated  and  satm-ated 
as  thoroughly  as  possible  with  an  unalterable  varnish  before  the  final 
filling  is  inserted. 

The  Sulfur  Dioxid  Method. — Reference  has  already  been  made  to 
sulfur  dioxid  as  the  single  example  of  the  reducing  t^^pe  of  bleaching 
agent.  Its  activity  is  due  to  its  affinity  for  oxygen,  and  it  bleaches 
by  seizing  upon,  and  combining  with,  that  element  of  the  color  molecule, 
thus  destroying  its  identity  and  consequently  its  color.  Attempts 
have  been  made  to  utilize  the  bleaching  property  of  sulfur  dioxid  in  the 
treatment  of  discolored  teeth  by  direct  application  of  the  solution  of  the 
gas  in  water  and  by  igniting  small  quantities  of  sulfur  in  the  root  canal 
by  means  of  the  electro-cautery  wire.     These  methods  have,  however, 


490  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

proved  inefficient.  The  gas  may  be  used  successfully  in  bleaching 
teeth  by  evolving  it  from  its  compounds  placed  in  the  cavity  and  root 
canal  in  a  manner  analogous  to  that  employed  in  the  Truman  chlorin 
process  already  described.  For  this  purpose  Dr.  Kirk's  method 
may  be  employed  conveniently:  100  grains  of  sodium  sulfite  and 
70  grains  of  boric  acid  are  separately  desiccated  and  afterward 
ground  together  in  a  warm  dry  mortar.  The  powder  is  then  to  be 
transferred  to  a  tightly-stoppered  bottle.  For  bleaching  purposes  the 
powder  is  packed  into  the  root  canal  and  cavity  of  the  tooth,  and  then 
moistened  with  a  drop  of  water  and  the  cavity  immediately  closed  as 
tightly  as  possible  with  a  stopping  of  gutta-percha  previously  prepared 
and  warmed.  A  reaction  ensues  between  the  boric  acid  and  sodium 
sulfite  whereby  sulfur  dioxid  is  liberated,  thus : 

2H3BO3  +  3Na2S03  =  2Na3B03  +  3H2O  +  3SO2. 

The  process  is  effective  in  many  cases  in  which  the  chlorin  methods 
have  failed,  but  is  slow  in  its  action,  and  is  largely  superseded  by  the 
hydrogen  dioxid  and  sodium  dioxid  methods. 


CATAPHORIC  BLEACHING   OF   TEETH. 

It  has  been  found  that  aqueous  solutions  of  hydrogen  dioxid  may  be 
carried  into  the  dentinal  structure  with  great  ease  by  the  cataphoric 
action  of  the  continuous  electric  current.  The  appliances  necessary 
for  tooth  bleaching  operations  by  this  means  are  practically  the  same 
as  those  required  in  the  treatment  of  hypersensitive  dentin.  The 
resistance  offered  by  the  hard  structures  of  the  tooth  is  much  greater 
after  loss  of  the  tooth  pulp,  requiring  a  much  higher  voltage  pressure 
to  drive  the  bleaching  agent  into  the  tissue.  While  in  some  cases 
twenty-five  to  thirty  volts  will  be  all  that  is  necessary,  other  cases  will 
require  as  high  as  sixty  volts  to  carry  1.5  milliamperes  of  current 
through  the  dentin.  The  ethereal  solution  of  hydrogen  dioxid  has 
been  found  to  oppose  too  great  resistance  to  the  current  but  the 
aqueous  solution,  containing  a  slight  addition  of  some  salt  to  increase 
its  conductivity,  is  entirely  manageable. 

A  25  per  cent,  aqueous  solution  of  hydrogen  dioxid  may  be  made 
quickly  by  shaking  together  in  a  test-tube  one  volume  of  water 
and  two  volumes  of  25  per  cent,  pyrozone.  The  H2O2  dissolves 
in  the  water,  and  the  ether  of  the  pyrozone  may  be  removed  by 
pouring  the  mixture  into  a  small  evaporating  dish  of  porcelain  or  glass 
and  gently  heating  it  over  a  water-bath  until  all  of  the  ether  has 
evaporated.    The  addition  of  a  small  quantity  of  sodium  acetate  or 


CATAPHORIC  BLEACHING  OF  TEETH  491 

sulfate  will  diminish  greatly  the  resistance  of  the  solution  to  the 
passage  of  the  current. 

With  the  tooth  isolated  by  the  rubber  dam  and  having  received  the 
treatment  preliminary  to  bleaching,  as  already  described  in  detail, 
the  aqueous  solution  of  H2O2  is  dropped  upon  cotton  in  the  tooth  cavity 
and  a  platinum  needle  anode  is  applied  in  contact  with  it.  The  cathode 
may  be  a  sponge  electrode  moistened  with  salt  solution  and  held  in  the 
hand  or  applied  to  the  cheek  or  neck.  The  hand,  however,  is  preferable 
because  of  the  amount  of  voltage  required  in  the  operation.  Great 
care  must  be  exercised  that  the  external  surfaces  of  the  tooth  are  kept 
dry,  so  that  short-circuiting  of  the  current  may  not  take  place.  In 
some  cases  a  more  rapid  effect  is  obtained  by  making  contact  of  the 
cathode  pole  through  a  needle  electrode  upon  the  external  surface  of 
the  tooth,  and  with  the  anode  applied  to  the  pyrozone  solution  on 
cotton  in  the  tooth.  The  cotton  must  at  all  times  be  kept  wet  with  the 
solution. 

The  arrangement  of  the  electric  terminals  with  respect  to  the  bleach- 
ing operation  is  both  theoretically  and  practically  correct  as  described, 
namely,  the  flow  of  current  should  be  from  the  anode  point  through 
the  bleaching  solution  and  tooth  and  the  body  of  the  patient  to  the 
cathode.  In  practice  it  has  been  found  in  some  cases  which  have  failed 
to  bleach,  with  the  elements  arranged  in  the  series  as  stated,  that  upon 
reversing  the  poles  and  direction  of  current  flow  the  bleaching  has 
followed  rapidly.  The  explanation  of  this  apparent  paradox  is  that 
by  the  application  in  normal  order  H2O2  was  first  carried  into  the  tubu- 
lar structure,  and  the  reversal  of  the  current  has  acted  upon  the  tubular 
contents  now  satiu-ated  with  the  dioxid,  and  by  its  propulsive  as  well 
as  electrolytic  effect  has  removed  the  pigmentary  matter  pulpward 
from  the  tubuli.  Bleaching  with  reversed  poles  would  be  impossible 
without  previous  saturation  of  the  dentin  by  the  dioxid  solution. 

Dr.  M.  W.  Hollingsworth  has  devised  an  ingenious  apparatus  for 
cataphoric  bleaching  which  is  of  special  value,  as  it  makes  possible  the 
enveloping  of  the  entire  tooth  with  the  bleaching  fluid,  in  which  it  is 
immersed.  The  appliance  is  shown  in  situ  in  Fig.  403,  and  consists 
of  a  thin  vulcanized  caoutchouc  bulb  shaped  like  the  bulb  of  a  medicine 
dropper.  Through  a  perforation  at  its  rounded  end,  made  with  the 
ordinary  rubber  dam  punch,  the  tooth  is  slipped  by  mounting  the  bulb 
on  the  applicator  (Fig.  404)  and  forcing  it  over  the  tooth  as  though  it 
were  a  rubber  dam.  A  glass  tube  is  then  attached  to  the  open  end  of 
the  bulb,  and  to  the  glass  tube  is  connected  a  spiral  platinum  wire 
electrode  (Fig.  405).  Before  the  electrode  is  attached  the  bulb  and 
glass  tube  are  filled  with  the  aqueous  pjTozone  solution  by  means  of  a 
duplex  sjT-inge  (Fig.  406),  the  lower  and  larger  bulb  of  which  exhausts 


492  DISCOLORED  TEETH  AND  THEIR  TREATMENT 


Fig.  403. — Hollingsworth's  device  for  applying  the  bleaching  agent  to  the  tooth. 


Fig.  404. — Applicator. 


Fig.  405. — Tube  electrode. 


Fig.  406. — Duplex  syringe. 


LIGHT  AS  AN  ADJUVANT  TO  BLEACHING  PROCESS         493 

the  contained  air  in  the  apparatus  and  the  smaller  thumb  bulb  injects 
the  bleaching  solution  into  the  exhausted  apparatus.  Connection  is 
now  made  with  the  source  of  current  as  usual,  and  the  bleaching  is  very 
rapidly  effected.  Dr.  Hollingsworth  recommends  the  addition  of 
about  1  per  cent,  of  zinc  sulfate  to  the  aqueous  pjTozone  solution, 
which  not  only  diminishes  the  resistance  to  the  passage  of  the  current, 
but  has  a  coagulating  effect  upon  the  bleached  organic  matter,  which 
gives  it  translucency  and  greatly  enhances  the  permanency  of  the 
operation.  The  results  obtained  by  this  method  are  extremely  satis- 
factory. 

LIGHT   AS    AN   ADJUVANT   TO   THE   BLEACHING   PROCESS. 

If  a  piece  of  raw  textile  fabric  is  subjected  to  the  simultaneous 
influence  of  air,  moisture  and  sunlight,  it  is  bleached.  This  process 
is  known  as  natural  or  Holland  bleaching  to  differentiate  it  from  chemi- 
cal or  artificial  bleaching.  Most  likely,  during  the  process  of  natural 
bleaching  ozone,  O3,  is  obtained  which  in  tm"n  is  split  up  in  O2  +  O 
(nascent  state).  This  very  slow  process  may  be  facilitated  materially 
by  utilizing  a  concentrated  solution  of  hydrogen  dioxid  in  the  presence 
of  concentrated  artificial  light. 

In  1907  Magay^  introduced  an  improved  method  of  bleaching  dis- 
colored teeth  which  consisted  in  applying  perhydrol  and  concentrated 
sunlight.  To  overcome  the  inconvenience  of  the  untrustworthy  sun- 
light, Levy,2  in  1912,  substituted  artificial  light  with  most  gratifying 
results. 

For  a  clear  understanding  of  the  action  of  light  in  this  respect,  it  is 
probably  not  amiss  to  recapitulate  briefly  the  nature  of  light  rays  from 
the  physicist's  point  of  view.  The  solar  spectrum  fmnishes  a  band  of 
colors  consisting  of  violet,  indigo,  blue,  green,  yellow,  orange  and  red 
shades,  which  overlap  each  other.  Beyond  either  end  of  the  visible 
spectrum  are  found  a  number  of  rays,  the  more  important  ones  being 
known  as  the  electric,  and  ultra-red  rays  near  the  red  shade  and  ultra- 
violet rays  near  the  violet  shade.  The  rays  between  the  ultra-red  and 
blue  division  are  heat  producers  and  are  spoken  of  as  thermic  or  caloric 
rays;  the  rays  between  the  red  and  violet  division  are  predominant  in 
the  production  of  light  and  are  referred  to  as  luminous  or  optic  rays, 
while  the  rays  between  the  red  and  the  tri-ultra-violet  division  exercise 
a  marked  chemical  influence  on  organic  and  inorganic  matter  and  are 
known  as  chemical  or  actinic  rays.  The  most  active  actinic  rays  are 
those  between  the  blue  and  ultra-violet  division  and  are  known  as 

1  Deutsche  Monatschrift  f.  Zahnheilkunde,  1907,  p.  65. 

2  Ibid.,  1912,  p.  138. 


494 


DISCOLORED  TEETH  AND  THEIR  TREATMENT 


Finsen  rays.  By  interposing  either  clear  or  various  colored  glass  lenses 
in  the  path  of  the  rays,  certain  rays  are  absorbed,  as,  for  instance,  red 
glass  obstructs  the  passage  of  the  light  and  chemical  rays,  clear  glass 
absorbs  most  of  the  blue  and  ultra-violet  rays  (the  Finsen  rays),  blue 
glass  causes  a  partial  absorption  of  heat  rays.  In  experimenting  with 
the  various  rays  to  ascertain  their  influence  on  the  bleaching  process, 
it  has  been  observed  that  primarily  the  heat,  and  to  a  less  extent  the 
luminous  rays,  are  the  principal  factors,  the  actinic  rays  apparently 
playing  no  part  therein.  The  source  of  light  for  this  purpose  may  be 
obtained  from  any  illuminating  device.  However,  a  light  of  very  high 
candle  power  which  can  be  focussed  in  the  desired  direction  is  to  be 


Heaty 
Rays^ 


Ultra  Red 

Optic^ 
Rays^ 

Red 

Orange 

Yellow 

Green 

.Cherr 
rActiv 

Blue 

Indigo 

Violet 

Ultra-violet 

ically 


VFi.nsen 
'     Rays 


Fig.  407. — Diagram  of  the  incomplete  spectrum. 


preferred.  A  tungsten  flash  light,  a  dental  illuminator,  an  electric 
arc  lamp  or  a  special  bleaching  apparatus  provided  with  a  suitable 
reflector  and  a  double  convex  collecting  lens  are  serviceable.  The 
preparation  of  the  tooth  for  bleaching  by  this  method  is  precisely  the 
same  as  outlined  above.  The  pulp  chamber  is  loosely  filled  with  cotton 
and  a  piece  of  gauze  is  tied  about  the  tooth  and  moistened  with  perhy- 
drol  applied  with  a  medicine  dropper.  The  light  is  focussed  directly 
upon  the  exposed  tooth  and  a  drop  of  perhydrol  is  added  from  time  to 
time  to  replace  the  solution  lost  by  evaporation.  In  the  course  of 
twenty  to  thirty  minutes,  the  tooth  is  usually  restored  to  its  normal 
color  in  such  cases  as  are  amenable  to  the  bleaching  action  of  the 


SPECIAL  DISCOLORATIONS  AND  THEIR  TREATMENT        495 

dioxids.     It  is  always  preferable  to  apply  a  second  treatment  after  the 
lapse  of  a  week. 

The  bleaching  of  discolored  teeth  by  the  combined  utilization  of 
concentrated  hydrogen  dioxid  and  light  offers  most  satisfactory  results. 

SPECIAL  DISCOLORATIONS    AND   THEIR   TREATMENT. 

Pulpless  teeth  are  especially  liable  to  discoloration  from  external 
and  accidental  causes.  If  decayed  and  the  cavity  has  remained 
unfilled  for  a  length  of  time,  many  substances  which  find  their  way  into 
the  oral  cavity  either  as  food  or  as  medicine  may  produce  discoloration 
when  absorbed  by  the  tooth  through  the  open  cavity  walls. 

Metallic  Salts. —  Metallic  salts  are  particularly  likely  to  cause  such 
staining  by  reaction  with  the  sulfids  with  which  the  dentin  structure 
is  usually  saturated  during  decomposition  of  its  organic  contents. 
Many  of  the  medicaments  used  in  pulp-canal  treatment,  or  even  for 
hjqpersensitive  dentin,  may  stain  the  tooth  structure,  and  finally,  the 
action  of  sulfids  in  the  structure  of  a  pulpless  tooth  may  react  with 
amalgam  fillings,  forming  salts  of  mercury,  silver,  tin,  copper,  etc., 
which  are  absorbed  by  the  tooth,  resulting  in  its  discoloration.  The 
treatment  of  these  stains,  which  were  grouped  as  Class  III  at  the 
beginning  of  this  chapter,  is  extremely  difficult  and  often  unsatisfactory. 
However,  there  may  arise  individual  cases  of  discoloration  of  this 
class.  It  is  of  the  utmost  importance  to  treat  these,  and  much  may  be 
accomplished  when  the  causes  of  the  discoloration  are  known  and  the 
proper  bleaching  method  is  applied. 

Gold  Stains. —  Gold  stains  may  arise,  as  has  been  indicated,  from  the 
injudicious  use  of  gold  instruments  or  failure  to  remove  all  gold  fillings 
when  applying  some  of  the  chlorin  methods  of  bleaching.  In  the 
course  of  time  the  tooth  assumes  a  pinkish  hue,  which  merges  into  a 
characteristic  violet  or  purple,  finally  becoming  black. 

Iron  Stains. —  Iron  stains  may  arise  from  the  use  of  steel  instruments 
in  connection  with  the  chlorin  methods  of  bleaching  or  in  contact  with 
iodin  or  any  of  the  mineral  acids  used  in  connection  with  canal  treat- 
ment. The  iron  stain  is  yellowish  at  first,  gradually  becoming  brown 
and  finally  black. 

Copper  and  Nickel  Stains.  — Copper  and  nickel  stains  may  arise  from 
contact  with  these  metals  or  their  alloys,  as  copper  amalgam  or  nickel 
or  German  silver  dowels  for  artificial  crowns  or  anchorages  for  fillings. 
The  stains  from  these  metals  are^ — for  copper,  bluish  to  black,  and  for 
nickel,  a  characteristic  chlorophyl  green,  which  eventually  becomes 
black. 

The  best  general  treatment  for  all  of  the  foregoing  stains  is  to  bleach 


496  DISCOLORED  TEETH  AND  THEIR  TREATMENT 

the  tooth  by  the  chlorin  method,  with  observance  of  the  several  precau- 
tions already  recommended;  and  when  the  color  of  the  metallic  stain 
has  been  discharged  by  conversion  of  the  dark-colored  salt  into  a  soluble 
chlorid,  wash  the  tooth  thoroughly  first  with  dilute  chlorin  water  50 
per  cent.,  and  afterward  with  hot  distilled  water,  to  remove  all  of  the 
metallic  chlorid  which  has  been  formed.  The  process  may  require 
repetition  to  secure  permanent  results. 

Silver  Stains — Silver  stains  are  comparatively  easy  to  remove,  either 
by  an  application  of  the  chlorin  method  or  by  saturating  the  tooth  with 
tincture  of  iodin,  thus  converting  the  silver  into  a  chlorid  or  iodid,  as 
the  case  may  be,  after  which  it  may  be  dissolved  out  with  a  saturated 
solution  of  ammonia  or  sodium  hyposulfite  applied  as  a  bath  to  the 
tooth.  For  this  purpose  the  Hollingsworth  bulb  dam  (see  Fig.  403) 
answers  admirably,  and  although  the  experiment  has  not  been  as  yet 
tried,  there  is  good  reason  to  believe  that  the  cataphoric  method  with 
electrodes  applied  in  reverse  order  would,  under  these  circumstances, 
greatly  facilitate  the  solution  and  removal  of  the  metallic  salts. 

Mercurial  Stains. —  Mercurial  stains  are  always  black  from  the 
formation  of  mercuric  sulfid,  and  are  removable  by  the  same  method 
as  are  silver  stains,  with  the  exception  that  when  the  stain  has  been 
converted  into  a  chlorid  by  the  chlorin  method,  the  mercuric  chlorid 
is  best  removed  by  an  aqueous  ammoniacal  solution  of  hydrogen 
dioxid,  or  when  the  stain  has  been  converted  into  mercuric  iodid  by  the 
use  of  a  saturated  solution  of  potassium  iodid.  In  both  cases  a  final 
washing  with  hot  distilled  water  is  a  sine  quo  non. 

Manganese  Stains. — ^  Manganese  stains  frequently  occur  from  the  use 
of  potassium  permanganate,  in  solution  or  in  substance,  in  the  treat- 
ment of  putrescent  canal  conditions.  The  manganese  stain  is  a  char- 
acteristic mahogany  brown.  It  is  removed  very  readily  by  a  25 
per  cent,  aqueous  solution  of  hydrogen  dioxid  in  which  oxalic  acid 
crystals  have  been  dissolved  to  saturation.  A  few  applications  of  this 
mixture  will  quickly  decolorize  the  stain,  after  which  a  liberal  treatment 
of  hot  distilled  water  is  required  as  in  the  foregoing  cases. 

Organic  Stains — Organic  stains  are  occasionally  observed  after  the 
use  of  organic  drugs  employed  in  the  treatment  of  infected  root  canals. 
Preeminent  among  these  drugs  are  the  essential  oils  of  cassia  and  to 
a  very  much  less  extent  that  of  cloves.  These  oils  contain  furfurol, 
a  colorless  pyromucic  aldehyd,  which  readily  turns  brown  on  exposure 
to  air  and  light  and  stains  the  tooth  structure  a  tan  color.  These 
pigments  are  removed  readily  by  any  one  of  the  dioxid  bleaching 
methods. 

Superficial  organic  stains  from  foodstuffs,  especially  fruits,  such  as 
blueberries,  black  cherries,  etc.,  from  the  use  of  tobacco  or  from  chewing 


SPECIAL  DISCOLORATION S  AND  THEIR  TREATMENT        497 

betel  nuts  and  the  green  discolorations  upon  the  teeth  of  children 
(growth  of  various  molds  and  fungi  upon  Nasmyth's  membrane  and 
formation  of  sulfomet hemoglobin)  and  occasionally  from  colored 
dentifrices,  are  usually  removed  readily  by  employing  a  fine  abrasive 
(pumice  stone)  mixed  into  a  paste  with  hydrogen  dioxid.  In  tobacco 
and  betel  nut  stains  alcohol  mixed  with  pumice  stone  powder  is  to  be 
preferred. 

In  bygone  days  it  was  customary  with  the  married  women  of  Japan 
to  blacken  their  teeth  with  a  concoction  known  as  ''Okaguro"  or 
*'Kane"  and  which  is  said  to  be  composed  of  urine,  iron  filings  and  sake. 
The  stain  produced  by  this  caustic  fluid  is  more  or  less  permanent. 
At  present,  this  custom  has  fallen  largely  into  disuse. 

In  all  cases  a  careful  diagnosis  of  the  chemical  nature  of  the  dis- 
coloration should  be  made  when  possible.  Much  information  upon 
this  point  may  be  gained  by  a  detailed  study  of  the  present  condition 
of  the  tooth  and  its  environment,  but  in  addition  to  this  the  patient 
should  be  questioned  as  to  the  history  of  the  case,  and  especially  as  to 
its  previous  treatment.  The  data  thus  obtained  should  be  noted 
carefully,  and  treatment  instituted  in  accordance  with  the  conditions 
to  be  met. 

Success  in  the  bleaching  of  teeth  demands  a  recognition  of  the  fact 
that  each  case  presents  individual  peculiarities,  that  the  problem  is 
essentially  a  chemical  one  always,  and  that  the  bleaching  method  in 
any  given  case  must  be  selected  with  special  reference  to  the  character 
of  the  discoloration  and  applied  with  due  care  to  its  details  in  order 
that  the  chemical  requirements  of  the  operation  may  be  met  intelli- 
gently, without  which  care  success  is  impossible. 


32 


CHAPTER   XII. 

LOCAL  ANESTHESIA. 

By  HERMANN  PRINZ,  M.D.,  D.D.S. 

Local  anesthetics  are  agents  which  are  employed  for  the  purpose  of 
producing  insensibility  to  pain  in  a  circumscribed  area  of  tissue. 

History. — ^From  an  historical  viewpoint,  comparatively  few  important 
facts  are  to  be  recorded  prior  to  the  introduction  of  cocain  for  the  pur- 
pose of  obtunding  pain  locally.  The  compression  of  nerve  trunks  for 
the  abolition  of  pain  seems  to  be  of  an  old  and  unknown  origin,  which 
was  revived  by  Guy  du  Chauliac  and  Ambroise  Pare,  and  indirectly 
found  a  permanent  place  in  surgery  as  the  Esmarch  elastic  bandage. 
Physically  reducing  the  temperature  of  a  part  of  the  body  by  the  appli- 
cation of  cold  was  instituted  much  later.  Bartholin  and  Severino 
introduced  this  method  in  the  middle  of  the  sixteenth  century.  It 
became  a  lost  art,  however,  until  John  Hunter,  of  London,  again  called 
attention  to  its  benefits  by  demonstrating  it  upon  animals,  and  Larrey, 
the  chief  surgeon  of  Napoleon's  army,  employed  it  for  amputations  in 
1807.  Through  the  efforts  of  Sir  B.  W.  Richardson,  in  1866,  it  was 
placed  upon  a  rational  basis  by  the  introduction  of  the  ether  spray. 
The  various  narcotics  which  were  employed  for  internal  purposes  were 
also  made  use  of  as  local  applications.  Mandragora,  henbane,  aconite, 
the  juice  of  the  poppyhead,  and  many  other  analgesic  drugs  enjoyed 
a  world-wide  reputation.  The  empirical  search  for  new  methods  and 
means  pressed  the  mysticism  of  the  electric  current  into  service,  open- 
ing a  prolific  field  to  the  charlatan  which  even  to  this  day  has  not  lost 
its  charm.  Richardson's  voltaic  narcotism  for  a  time  attracted  the 
attention  of  the  medical  profession;  and  Francis,  in  1858,  recommended 
the  attachment  of  the  electric  current  to  the  handles  of  the  forceps  for 
the  painless  extraction  of  the  teeth,  and  as  dental  markets  still  contain 
appliances  of  this  nature  for  sale,  it  seems  that  the  method  is  still  in 
vogue  with  some  operators.  In  the  early  days  of  modern  dentistry 
we  met  with  many  feeble  efforts  to  alleviate  pain  during  trying  oper- 
ations. Chloroform,  alcohol,  ether,  aconite,  opium,  the  essential  oils, 
and  many  other  drugs  were  the  usual  means  employed,  either  simply 

(498) 


MEANS  OF  PRODUCING  LOCAL  ANESTHESIA  499 

or  as  compounds,  usually  under  fanciful  names,  for  such  purposes. 
Snape's  calorific  fluid,  composed  of  chloroform,  tincture  of  lemon 
balm,  and  oil  of  cloves;  nabolis,  consisting  of  glycerite  of  tannic  acid 
and  a  small  quantity  of  chloral  hydrate;  Morton's  letheon,  which  was 
sulphuric  ether  mixed  with  aromatic  oils,  are  examples  of  proprietary 
preparations  which  enjoyed  quite  a  reputation  in  their  time. 

In  1844  F.  Rynd,  an  Irish  surgeon,  introduced  a  method  of  general 
medication  by  means  of  hypodermic  injections  which,  in  1853,  was 
much  improved  by  Alexander  Wood,  of  Edinburgh.  It  was  suggested 
at  once  that  such  drugs  as  morphia  or  tincture  of  opium  be  employed 
for  the  purpose  of  producing  local  anesthesia.  The  results  were  not 
encouraging,  however,  until  Koller,  in  1884,  advocated  cocain.  With 
the  introduction  of  this  drug  into  therapeutics,  local  anesthesia  achieved 
results  which  were  beyond  expectations,  and  its  adoption  created  a 
new  erajn  local  anesthesia. 

Means  of  Producing  Local  Anesthesia. ^ — The  term  anesthesia  (without 
sensation),  which  was  suggested  to  Dr.  Morton  in  1846  by  that  great 
physician-litterateur,  Oliver  Wendell  Holmes,  is  usually  defined  as  an 
artificial  deprivation  of  all  sensation,  while  the  mere  absence  of  pain  is 
referred  to  as  analgesia.  Correctly  speaking,  the  term  local  anes- 
thesia is  partially  a  misnomer.  In  producing  local  anesthesia  we  do 
not  fully  comply  with  all  the  requirements  that  anesthesia  demands, 
because  a  part  of  the  sensorium — the  sense  of  touch,  for  instance — is 
not  abolished.  The  term  local  anesthesia  has,  however,  acquired 
such  universal  recognition  that  it  would  seem  unwise  to  recommend  a 
change. 

Anesthesia  may  be  produced  artificially  by  inhibiting  the  sensory 
nerve  fibers  at  their  central  end-organs  in  the  brain  or  at  their  peri- 
pheral end-organs  in  the  tissues,  thus  producing  general  and  local 
anesthesia.  Local  anesthesia  may  be  obtained  in  two  definite  ways: 
we  may  inhibit  the  function  of  the  peripheral  nerves  in  a  circum- 
scribed area  of  tissue,  and  refer  to  this  process  as  terminal  anesthesia; 
or,  we  may  block  the  conductivity  of  a  sensory  nerve  trunk  somewhere 
between  the  brain  and  periphery,  and  speak  of  it  as  conduction  anes- 
thesia. Dental  terminal  anesthesia  is  usually  produced  by  a  sub- 
periosteal injection  (indirect  anesthetization)  or  a  peridental  injection 
(direct  anesthetization),  while  conduction  anesthesia  may  be  pro- 
duced by  injecting  into  the  nerve  trunk  proper — endoneiu"al  injection — 
or  by  injecting  into  the  tissues  siu-rounding  a  nerve  trunk— perineural 
injection.  The  latter  form  is  the  usual  method  pursued  when  conduc- 
tion anesthesia  for  dental  purposes  is  indicated. 


500  LOCAL  ANESTHESIA 

LOCAL  ANESTHESIA. 


Terminal  anesthesia  Conduction  anesthesia 


Subperiosteal  Peridental  Endoneural  Perineural 

injection  injection  injection  injection 

The  successful  practice  of  local  anesthesia  involves  the  carefully 
adjusted  cooperation  of  a  number  of  important  details,  each  one 
constituting  a  definite  feature  in  itself,  which,  when  neglected,  must 
necessarily  result  in  failure.    The  more  important  details  follow: 

1.  A  sterile  solution  of  drugs  possessing  active  anesthetic  potencies 
and  which,  in  their  composition,  must  correspond  to  the  physical  and 
physiologic  laws  which  govern  certain  functions  of  the  living  cells. 

2.  A  carefully  selected  sterile  hypodermic  armamentarium. 

3.  A  complete  mastery  of  the  technic. 

4.  A  proper  selection  of  the  correct  methods  of  injection  suitable  for 
the  case  in  hand. 

5.  Suitable  preparation  of  the  site  of  injection. 

6.  The  complete  cooperation  of  the  patient. 

7.  Good  judgment  of  prevailing  conditions. 

PHYSIOLOGIC  ACTION  OF  ANESTHETICS. 

According  to  more  recent  therapeutic  conceptions,  it  is  generally 
recognized  that  a  drug  or  combination  of  drugs  which  simultaneously 
produces  local  anemia  and  inhibition  of  the  functions  of  the  sensory 
nerves  in  a  circumscribed  area  of  tissue  is  the  logical  solution  of  the 
question  of  local  anesthesia.  Certain  important  factors,  however, 
relative  to  the  physiologic  and  physical  action  of  the  solution  employed 
for  hypodermic  injection  upon  the  cell,  govern  the  successful  appli- 
cation of  such  methods.  It  is  of  prime  importance,  therefore,  to 
comply  with  the  laws  regulating  the  absorption  of  injected  solutions, 
namely,  osmotic  pressure. 

If  we  separate  two  solutions  of  salt  of  different  concentration  by  a 
permeable  membrane,  a  continuous  current  of  salt  and  water  through 
the  membrane  results,  which  ceases  only  after  equalization  of  the  den- 
sity of  the  two  liquids,  namely,  when  equal  osmotic  pressure,  according 
to  the  Boyle — ^Van't  Hoff's  Law — is  established.  The  current  passes 
in  both  directions,  drawing  salt  from  the  stronger  to  the  weaker  solu- 
tion and  water,  vice  versa,  until  osmotic  equilibrium  is  obtained.    The 


PIIYSIOLOaiC  ACTION  OF  ANESTHETICS  .jlJl 

resultant  solutions  are  termed  isotonic  (I)e  Vries).  Osmotic  pressure 
is  a  physical  phenomenon  which  is  possessed  by  water  and  all  aqueous 
solutions;  it  is  dependent  upon  the  number  of  molecules  of  salt  present 
in  the  solution  and  upon  their  power  of  dissociation.  In  organized 
nature  these  osmotic  interchanges  are  an  important  factor  in  regu- 
lating the  tissue  fluids  of  both  animals  and  plants.  In  the  animal 
tissue  the  circulation  depends  principally  upon  the  mechanical  force 
exerted  by  the  heart.  The  life  of  the  cell  depends  upon  the  continuous 
passage  of  the  fluids  which  furnish  the  nutrient  materials,  consisting  of 
water,  salts  and  albumin.  These  chemicals  are  normally  present  in 
certain  definite  proportions.  The  membrane  of  the  living  cell  is, 
however,  only  semi-permeable,  namely,  the  cell  readily  absorbs  dis- 
tilled water  when  surrounded  therewith;  it  becomes  macerated, 
loses  its  normal  structure  and  finally  dies.  If,  on  the  other  hand,  the 
siuTounding  fluid  be  a  highly  concentrated  salt  solution,  the  solution 
absorbs  water  from  the  cell;  no  salt  molecules  enter  the  cell  body  proper. 
The  cell  shrinks  and  finally  dies.  This  process  of  cell  death  in  general 
pathology  is  referred  to  as  necrobiosis. 

A  further  important  factor  teaches  us  that  all  aqueous  solutions 
which  are  isotonic  possess  the  same  freezing  point,  namely,  all  solutions 
possessing  an  equal  freezing  point  are  equimolecular  and  possess 
equal  osmotic  pressure.  This  law  of  physical  chemistry  has  materially 
simplified  the  preparation  of  such  solutions.  The  freezing  point  of 
human  blood,  lymph,  serum,  etc.,  has  been  found  to  equal,  approxi- 
mately, 0.55°  C,  which  in  turn  corresponds  to  a  0.85  per  cent,  sodium 
chlorid  solution.  Such  a  solution  is  termed  a  physiologic  salt  solution. 
In  the  older  works  on  physiology  a  0.6  per  cent,  sodium  chlorid  solu- 
tion is  referred  to  as  a  physiologic  salt  solution;  this  solution  corre- 
sponds to  the  density  of  the  blood  of  a  frog.  A  slight  deviation  above 
and  below  the  normal  percentage  of  the  solid  constituents  is  per- 
missible. When  physiologic  salt  solution  at  body  temperature  is 
injected  into  the  loose  connective-tissue  under  the  skin  in  moderate 
quantities,  neither  swelling  nor  shrinkage  of  the  cells  as  such  occurs; 
a  simple  wheal  is  formed  which  soon  disappears;  therefore  no  irri- 
tation results,  and  no  pain  is  felt.  Similar  bodies  which  are  equally 
soluble  in  water  act  in  the  same  manner,  with  the  exception  of  the 
salts  of  the  alkali  and  earth  metals,  such  as  potassium  or  sodium  bromid. 
The  latter  substances  produce  intense  physical  irritation,  followed  by 
prolonged  anesthesia,  and  consequently,  are  termed  by  Liebreich 
"painful  anesthetics."  If,  on  the  other  hand,  simple  distilled  w^ater 
be  injected,  a  superficial  anesthesia  only  is  produced;  the  injection 
itself  is  very  painful  and  acts  as  a  direct  protoplasm  poison  by  macer- 
ating the  cell  contents  and  resulting  in  severe  damage  or  even  death 


502  LOCAL  ANESTHESIA 

of  the  cell.  If  distilled  water  approximately  at  the  ratio  of  10  drams 
to  the  pomid  of  body  weight  be  injected  into  dogs,  they  will  succumb 
in  a  short  time.  The  injection  of  higher  concentrated  salt  solution 
produces  opposite  effects;  water  is  removed  from  the  cells  with  more 
or  less  pronounced  pain,  followed  by  superficial  anesthesia.  The  red 
corpuscles  are  extremely  susceptible  to  any  injected  fluid  which  is  not 
isotonic  in  its  nature.  They  are  destroyed  (hemolysis)  by  the  injection 
of  fluids  which  are  not  represented  by  an  isotonic  salt  solution.  Hypo- 
tonic solutions  cause  swelling  of  the  tissues,  while  h^-pertonic  solutions 
produce  shrinkage.  These  manifestations  are  proportionately  the 
more  intense  the  further  the  solution  is  removed  from  the  freezing  point 
of  the  blood.  Furthermore,  hypotonic  solutions  as  well  as  hypertonic 
solutions,  require  much  more  time  for  their  absorption  than  isotonic 
solutions;  the  osmotic  pressure  must  be  standardized  to  the  surround- 
ing tissue  fluids. 

Local  anemia  prevents  the  rapid  absorption  of  fluids  that  are 
injected  into  the  affected  area.  Retarded  absorption  means  increased 
action  and  consumption  of  the  injected  drug  and,  as  a  consequence," 
less  danger  from  general  absorption. 

The  more  important  means  to  produce  local  anemia  are:  (1)  the 
Esmarch  elastic  bandage;  (2)  the  application  of  cold,  and  (3)  the 
extract  of  the  suprarenal  capsule. 

Some  observers  have  maintained  that  local  anemia  produces  anes- 
thesia. This,  however,,  is  not  the  case;  it  is  merely  an  important  means 
of  confining  the  injected  anesthetic  to  the  anemic  region,  and  thus 
bringing  about  an  increased  and  prolonged  action  of  the  drug.  Con- 
sequently, the  concentration  of  the  anesthetic  solution  may  be  of  a 
lower  percentage,  which,  of  course,  lessens  the  danger  of  intoxication. 
For  plausible  reasons  the  Esmarch  elastic  bandage  cannot  be  made 
use  of  for  dental  operations. 

Physically  reducing  the  temperature  of  the  body  by  the  application 
of  cold  (ice  pack,  ice  and  salt  mixture,  cold,  metals,  etc.),  was  practiced 
by  the  older  surgeons.  Arnott  in  1849  and  Blundell  in  1855  advocated 
ice  packs  for  the  painless  extraction  of  teeth.  Through  the  efforts  of 
Sir  B.  W.  Richardson,  in  1866,  this  method  was  placed  on  a  rational 
basis  by  the  introduction  of  the  ether  spray.  To  obtain  good  results, 
a  pure  ether  (boiling  point  95°  F.,  35°  C.)  free  from  water  is  necessary. 
Certain  other  volatile  hydrocarbons  possess  similar  properties  in  vary- 
ing degrees,  depending  upon  their  individual  boiling  point.  In  1867 
Rottenstein  called  attention  to  the  use  of  ethyl  chlorid  as  a  refrigerating 
agent,  and  Rhein,  in  1889,  introduced  methyl  chlorid  for  the  same 
purpose.  In  1891,  Redard  reintroduced  ethyl  chlorid  as  a  local  anes- 
thetic, which  since  has  become  known  by  many  trade  names — as 


ETHYL  CHLORID  AND  ITS  ADMINISTRATION  503 

antidolorine,  kelene,  narcotile,  etc.  Mixtures  of  the  first  two  in 
various  proportions  known  as  anestol,  anestile,  coryl,  metethyl,  etc., 
are  extensively  used  in  minor  oral  and  general  surgery.  A  pure  ethyl 
chlorid  (boiling  point  55°  F.,  13°  C.)  is  best  suited  for  this  purpose, 
as  it  lowers  the  temperature  of  the  tissues  sufficiently  to  produce  a 
short  superficial  anesthesia  in  a  few  minutes.  Too  rapid  cooling  or  pro- 
longed freezing  by  methyl  chlorid  (boiling  point,  —12°  F.,  —24.5°  C.) 
or  the  various  mixtures  thereof,  produces  deeper  anesthesia.  Such 
procedures  are  dangerous  because  they  frequently  cut  off  circulation 
in  the  affected  part  so  completely  as  to  produce  sloughing  (necrosis) . 
Liquid  nitrous  oxid,  liquid  or  solid  carbon  dioxid  (recently  known  as 
carbonic  acid  snow),  and  liquid  air,  all  of  which  have  a  boiling  point 
far  below  zero,  are  recommended  for  similar  purposes,  but  they  require 
cumbersome  apparatus  and  are  extremely  dangerous. 


Fig.  408. — Ethyl  chlorid  spray  tube.     (Metal.) 

ETHYL  CHLORID  AND  ITS  ADMINISTRATION. 

Ethyl  chlorid  (monochlorethane;  hydrochloric  ether;  C2H5CI).  "A 
haloid  derivative,  prepared  by  the  action  of  hydrochloric  acid  gas 
on  absolute  alcohol."  At  normal  temperature,  ethyl  chlorid  is  a  gas 
and  under  a  pressure  of  two  atmospheres  it  condenses  to  a  colorless, 
mobile,  very  volatile  liquid,  having  a  characteristic,  rather  agreeable 
odor,  and  burning  taste.  It  boils  at  about  55°  F.  (13°  C.)  and  is  very 
inflammable,  burning  w4th  a  smoky,  green-edged  flame.  It  is  stored 
in  sealed  glass  or  metal  tubes,  and  when  liberated  at  ordinary  room 
temperature,  70°  F.  (21°  C.)  evaporates  at  once.  In  commerce  it  is 
supplied  in  plain  or  graduated  tubes  of  from  30  to  60  grams  capacity, 
or  stored  in  metallic  cylinders  holding  from  60  to  100  grams  or  more. 
To  remove  the  ethyl  chlorid  from  the  hermetically  sealed  small  tubes, 
the  neck  must  be  broken  off,  while  the  larger  glass  and  metallic  tubes 
are  provided  with  suitable  stopcocks  of  various  designs  to  allow  definite 
amounts  of  the  liquid  to  be  released. 

Mode  of  Application. — ^For  the  extraction  of  teeth,  immediate  removal 
of  the  pulp,  opening  of  abscesses  and  other  minor  operations  about  the 


504  LOCAL  ANESTHESIA 

oral  cavity,  the  tube  should  be  warmed  to  body  temperature  by  placing 
it  in  heated  water,  and  its  capillary  end  should  be  held  about  six  to 
ten  inches  from  the  field  of  operation.  The  distance  depends  upon  the 
size  of  the  orifice  of  the  nozzle.  Complete  vaporization  should  always 
be  produced.  The  Gebauer  tube  is  fitted  with  a  spray  nozzle,  which 
shortens  the  distance  one  to  two  inches,  and  is  especially  well  adapted 
for  dental  purposes.  The  stream  is  directed  upon  the  tissues  until 
the  latter  are  covered  with  ice  crystals  and  have  turned  white.  For 
the  extraction  of  teeth,  the  liquid  should  be  projected  directly  upon  the 
surface  of  the  gum,  as  near  to  the  apex  of  the  root  as  possible,  but  care 
should  be  taken  to  protect  the  crown  of  the  tooth  on  account  of  the 
painful  action  of  cold  on  this  part.  The  tissues  to  be  anesthetized 
should  first  be  dried  and  well  surrounded  by  a  film  of  vaselin  or  glycerin, 
and  protected  by  cotton  rolls  and  napkins,  to  prevent  the  liquid  from 
running  into  the  throat.  Let  the  patient  breathe  through  the  nose. 
Occasionally  light  forms  of  general  anesthesia  are  induced  by  inhaling 
the  vapor.  On  account  of  the  difficulty  of  directing  the  stream  of 
ethyl  chlorid  upon  the  tissue  in  the  posterior  parts  of  the  mouth,  it  is 
not  successfully  applied  to  those  regions.  The  intense  pain  produced 
by  the  extreme  cold  prohibits  its  use  in  acute  pulpitis  and  in  peri- 
cementitis. To  anesthetize  the  second  and  third  branches  of  the 
fifth  nerve,  it  is  recommended  that  the  stream  of  ethyl  chlorid 
be  directed  upon  the  cheek  in  front  of  the  tragus  of  the  ear,  but  the 
author  has  not  seen  any  good  results  from  such  a  procedure.  Caution 
should  be  exercised  in  using  ethyl  chlorid  near  an  open  flame  or  in 
conjunction  with  the  thermocautery,  as  severe  burns  have  resulted  by 
setting  the  inflammable  vapor  on  fire. 

THE  ACTIVE  PRINCIPLE  OF  THE  SUPRARENAL  CAPSULE  AND  ITS 
SYNTHETIC  SUBSTITUTES. 

Within  the  last  decade  the  active  principle  of  the  suprarenal  capsule 
has  evoked  extensive  comments  in  therapeutic  literature.  It  has  been 
isolated  by  a  number  of  investigators  under  different  names,  as  epi- 
nephrin  by  Abel,  suprarenin  by  Fuerth,  and  adrenalin  by  Takamine 
and  Aldrich.  Many  other  titles  are  given  to  this  chemical,  as  adneph- 
rin,  paranephrin,  suprarenalin,  supracapsulin,  hemostasin,  etc.  Epi- 
nephrin  is  a  grayish-white  powder,  slightly  alkaline  in  reaction,  and 
perfectly  stable  in  dry  form.  It  is  sparingly  soluble  in  cold  and  more 
soluble  in  hot  water,  is  insoluble  in  ether  or  alcohol,  and  with  acids  it 
readily  forms  soluble  salts.  The  preparation  that  is  employed  mostly 
for  therapeutic  purposes  is  a  solution  of  epinephrin  hydrochlorid  in  a 
1  to  1000  physiologic  salt  solution,  to  which  preservatives,  as  small 


ACTIVE  PRINCIPLE  OF  THE  SUPRARENAL  CAPSULE       505 

quantities  of  chloretoiie,  tlixinol,  etc.,  are  added.  Alkali  of  any  kind 
is  especially  destructive  to  this  sensitive  alkaloid;  even  the  small 
quantities  of  free  alkali  present  in  ordinary  glass  are  dangerous. 
Bottles  intended  for  storing  epinephrin  solutions  should  be  made  of 
amber-colored  alkali-free  or  Jena  glass  or  bottles  of  ordinary  glass 
should  be  immersed  in  a  diluted  solution  of  hydrochloric  acid  for  a 
few  days  and  then  thoroughly  washed  in  running  water  before  they 
are  used.  Epinephrin  solution  does  not  keep  well.  On  exposure  to 
the  air  or  light  it  is  easily  decomposed,  becoming  pink,  then  red,  and 
finally  brown,  and  with  this  change  of  color  its  physiologic  property  is 
destroyed.  If  the  epinephrin  solution  be  further  diluted,  it  becomes 
practically  worthless  within  a  few  days. 

When  epinephrin  is  injected  into  the  tissues,  even  in  extremely  small 
doses,  it  temporarily  raises  the  arterial  blood-pressure,  acting  as  a 
powerful  vasoconstrictor  by  stimulating  the  smooth  muscular  coat  of 
the  bloodvessels,  and  thus  produces  local  anemia.  Large  doses  finally 
reduce  the  blood-pressure,  and  heart  failure  results.  The  respiration 
at  first  quickly  increases,  but  slows  down  and  finally  stops  with  expir- 
ation. Its  action  is  largely  confined  to  the  smooth  muscle  fibers  of  the 
peripheral  vessels.  Epinephrin  is  destroyed  by  the  living  tissue  cells, 
the  body  ridding  itself  of  the  poison  in  some  unknown  manner.  While 
epinephrin  does  not  possess  local  anesthetic  action,  it  increases  very 
markedly  the  effect  of  certain  anesthetics  when  combined  with  them. 
These  observations  are  of  vast  importance  in  connection  with  the  pro- 
duction of  local  anesthesia.  Carpenter,  Peters,  Moller,  and  others 
referred  to  the  use  of  epinephrin  in  this  respect,  and  finally  Braun,  in 
1902,  published  his  classic  researches,  and  to  him  and  his  co-workers, 
especially  Heinze  and  Laewen,  belongs  the  credit  of  establishing  a 
rational  basis  for  the  production  of  local  anesthesia.  It  is  claimed  that 
secondary  hemorrhage  frequently  occurs  after  the  anemia  produced  by 
the  epinephrin  has  subsided,  and  that  the  tissues  themselves  suffer 
from  the  poisoning  effect  of  the  drug,  resulting  in  necrosis.  Such 
results  are  produced  only  by  the  injection  of  too  large  quantities,  w^hich, 
by  their  deeper  action,  close  up  the  larger  capillaries.  The  prolonged 
anemia  will  give  way  to  a  dilation  of  the  bloodvessels,  and  if  the  tissues 
are  too  long  deprived  of  the  circulation,  we  are  able  to  miderstand 
why  sloughing  may  result.  Small  doses  of  epinephrin  have  no  effect 
upon  the  tissues  or  on  the  healing  of  a  wound.  Palpitation  of  the 
heart  and  muscular  tremor,  which  were  occasionally  noticed  in  the 
early  period  of  th-e  use  of  the  drug,  are  the  direct  result  of  too  large 
doses.  Recently  a  synthetic  epinephrin  has  been  successfully  pre- 
pared by  Stolz,  which,  with  hydrochloric  acid,  forms  a  stable  and 
readily  soluble  salt.    It  is  known  as  synthetic  suprarenin  hydrochlorid. 


506  LOCAL  ANESTHESIA 

The  new  chemical  has  been  carefully  tested  physiologically  and  in 
clinical  work,  and  the  consensus  of  opinion  points  to  the  fact  that  it  is 
not  only  equal,  but  in  certain  respects  superior,  to  the  organic  prepara- 
tions. Synthetic  suprarenin  solutions  may  be  sterilized  readily  by  boiling. 
They  are  relatively  stable,  and  their  chemical  purity  insures  uniform 
results.  They  are  comparatively  free  from  dangerous  side  actions. 
The  author's  observations  regarding  the  value  of  synthetic  suprarenin 
relative  to  its  general  behavior  are  in  full  accordance  with  the  above 
statements,,  and  its  advantage  over  the  organic  preparations  has  led 
him  to  adopt  it  as  a  component  in  the  preparation  of  local  anesthetic 
solutions.  For  dental  purposes,  that  is  for  injecting  into  the  gum 
tissue,  the  dose  may  be  limited  to  one  drop  of  the  epinephrin  solution 
(1  to  1000)  or  the  synthetic  suprarenin  solution  (1  to  1000)  added  to 
each  cubic  centimeter  of  the  anesthetic  solution,  5  drops  being  approxi- 
mately the  maximum  dose  to  be  injected  at  one  time. 

The  dosage  of  the  relative  amounts  of  epinephrin  solution  may  be 
arranged  as  follows: 

Add  1  drop  of  epinephrin  to  1  c.c.  of  the  novocain  solution. 

Add  2  drops  of  epinephrin  to  3  c.c.  of  the  novocain  solution. 

Add  3  drops  of  epinephrin  to  5  c.c.  of  the  novocain  solution. 

Add  4  drops  of  epinephrin  to  8  c.c.  of  the  novocain  solution. 

Add  5  drops  of  epinephrin  to  10  or  more  c.c.  of  the  novocain  solution. 

THE  LOCAL  ANESTHETICS. 

Cocain. — Cocain,  when  injected  into  the  tissues,  produces  typical 
local  and  general  effects.  Locally,  it  possesses  a  definite  affinity  for 
the  peripheral  nerves;  it  causes  constriction  of  the  smaller  arteries, 
producing  slight  anemia  in  the  injected  area  with  diminished  action 
of  the  leukocytes.  However,  different  parts  of  the  organism  require 
different  doses  to  bring  about  the  same  reaction.  Upon  mucous  sur- 
faces, paralysis  of  the  sensory  nerves  is  produced;  the  senses  of  touch 
and  smell  are  temporarily  inhibited.  The  blood  and  the  circulation 
suffer  little.  If  cocain  in  sufficient  quantities  be  absorbed  by  the 
circulation,  general  manifestations  are  produced  from  bringing  other 
tissues  in  close  contact  with  the  poison.  The  principal  disturbances 
of  the  central  nervous  system  make  themselves  known  by  vertigo,  a 
very  soft  pulse,  enlarged  and  staring  pupils,  and  difficult  respiration. 
Vomiting  may  occur;  the  throat  feels  dry;  intense  excitement  is 
followed  by  epileptiform  spasms;  finally  complete  loss  of  sensation  and 
motility  results,  which  terminates  in  death  from  cessation  of  respiration. 
The  general  character  of  the  disturbances  is  closely  related  to  that 
which  occurs  in  chloroform  or  ether  poisoning.    The  typical  picture  of 


LOCAL  ANESTHETICS  .  507 

cocain  poisoning  is  produced  when  the  blood  flowing  through  the 
central  nervous  system  contains  a  sufficient  quantity  of  the  drug, 
even  for  a  moment  only,  which  is  dangerous  to  this  organ.  No 
maximum  dose  can  be  positively  established.  This  is  equally  true  of 
chloroform  and  ether  when  used  for  general  anesthetic  purposes.  The 
many  cases  of  so-called  idiosyncrasy  probably  find  an  explanation  in 
the  too  large  doses  which  formerly  were  administered  so  frequently. 

With  our  increased  knowledge  of  the  action  of  cocain  upon  the 
tissues  and  a  proper  technic  of  the  injection,  dangerous  results  are 
comparatively  rare  at  present.  No  direct  antidotes  are  known;  the 
treatment  of  general  intoxication  is  purely  symptomatic.  Anemia  of 
the  brain,  which  is  of  little  consequence,  may  be  overcome  readily  by 
placing  the  patient  in  a  recumbent  position  or  by  complete  inversion, 
if  necessary.  As  a  powerful  dilator  of  the  peripheral  vessels  the  vapors 
of  amyl  nitrite  are  exceedingly  useful ;  it  is  best  administered  by  placing 
3  to  5  drops  of  the  fluid  upon  a  napkin  and  holding  it  before  the  nostrils 
for  inhalation.  Flushing  of  the  face  and  an  increase  in  the  frequency 
of  the  pulse  follow  almost  momentarily.  For  convenience,  amyl 
nitrite  may  be  procured  in  small  glass  capsules,  holding  the  necessary 
quantity  for  one  inhalation.  Nausea  may  be  remedied  by  administer- 
ing small  doses  of  spirits  of  peppermint,  aromatic  spirits  of  ammonia, 
etc.  To  overcome  the  disturbances  of  respiration^  quickly  instituted 
artificial  respiration  is  the  alpha  and  omega  of  all  methods  of  resusci- 
tation. In  cases  of  shock,  Mumford  recommends  the  hypodermic 
injection  of  morphin.  Engstadt  lauds  very  highly  the  administration 
of  ether  for  such  purposes  and  claims  that  it  is  the  antidote  for  cocain 
and  novocain.  To  obtain  the  best  results,  the  ether  should  be  admin- 
istered upon  a  mask  by  the  drop  method  and  only  to  the  degree  of 
mild  surgical  analgesia. 

The  relative  toxicity  of  a  given  quantity  of  cocain  solution  depends 
upon  the  concentration  of  its  solution.  Reclus  and  others  have  clearly 
demonstrated  that  a  fixed  quantity  of  cocain  in  a  5  per  cent,  solution 
is  almost  equally  as  poisonous  as  five  times  the  same  quantity  in  a 
I  per  cent,  solution.  From  the  extensive  literature  on  the  subject, 
we  are  safe  in  fixing  the  strength  of  the  solution  for  dental  purposes 
at  1  per  cent.  This  quantity  of  cocain  raises  the  freezing  point  of  dis- 
tilled water  just  a  little  above  0.1°  C.  To  obtain  an  isotonic  solution 
corresponding  to  the  freezing  point  of  the  blood,  0.8  per  cent,  of  sodium 
chlorid  must  be  added.  Having  thus  prepared  a  cocain  solution  which 
is  equal  to  the  blood  in  its  osmotic  pressure  upon  the  cell  wall,  it  is 
necessary  to  aid  the  slightly  vasoconstrictor  power  of  the  drug  by  the 
addition  of  a  moderate  quantity  of  epinephrin,  thus  increasing  the 
confinement  of  the  solution  to  the  injected  area  by  producing  a  deeper 


508  .  LOCAL  ANESTHESIA 

anemia,  for  a  two-fold  purpose:  (1)  to  act  as  a  means  of  increasing 
the  anesthetic  effect  of  cocain,  and  (2)  to  lessen  its  toxicity  upon  the 
general  system  by  slower  absorption.  As  stated  above,  1  drop  of 
epinephrin  solution  added  to  1  c.c.  of  the  isotonic  cocain  solution  is 
sufficient  to  produce  the  desired  effect. 

A  suitable  solution  for  dental  purposes  may  be  prepared  as  follows: 

Cocain  hydrochloric! 5  gr.  (0.30  gm.) 

Sodium  chlorid 4  gr.  (  0.25  gm.) 

Sterile  water 1  fl.  oz.         (30.00  c.c.) 

To  each  syringeful  (2  c.c.)  add  one  drop  of  epinephrin  chlorid  solu- 
tion when  used. 

Ready-made  cocain  solutions  are  sterilized  with  difficulty  and  will 
not  keep  when  frequently  exposed  to  the  air.  Ready-made  anesthetic 
solutions  as  found  in  the  market  usually  contain  preservatives,  such 
as  phenol,  naphthol,  boric  acid,  iodin,  essential  oils,  alcohol,  etc.,  in 
variable  quantities.  Some  of  these  solutions  have  a  distinct  acid 
reaction.  While  they  may  produce  a  serviceable  degree  of  anesthesia; 
they  usually  damage  the  injected  tissues  sufficiently  to  retard  the 
normal  process  of  wound  healing. 

Substitutes  of  Cocain. — ^Ever  since  the  introduction  of  cocain  into 
materia  medica  for  the  purpose  of  producing  local  anesthesia,  quite  a 
number  of  substitutes  have  been  placed  before  the  profession,  for  which 
superiority  in  one  respect  or  another  is  claimed  over  the  original 
cocain.  The  more  prominent  members  of  this  group  are  tropacocain, 
the  eucains,  acoin,  nirvanin,  alypin,  stovain,  novocain,  quinin  and 
urea  hydrochlorid.  None  of  these  compounds,  with  the  exception  of 
novocain,  now  also  known  as  procain,  has  proved  satisfactory  for  the 
purpose  in  view.  The  classical  researches  of  Braun  have  established 
certain  facts  which  are  essential  to  the  value  of  a  local  anesthetic. 
These  facts  concern  their  relationship  to  the  tissues  in  regard  to  their 
toxicity,  irritation,  solubility  and  penetration,  and  to  the  toleration 
of  epinephrin. 

It  is  not  necessary  to  enter  into  a  discussion  of  the  pharmacologic 
action  of  the  drugs  usually  classified  as  local  anesthetics.  Let  it  suffice 
to  state  how  the  above  mentioned  drugs  fulfil  the  demands  of  Braun. 
Tropacocain  is  less  poisonous,  but  also  less  active  than  cocain,  and 
completely  destroys  the  action  of  epinephrin;  the  eucains  partially 
destroy  the  epinephrin  action,  and  are,  comparatively  speaking, 
equally  as  poisonous  as  cocain;  acoin  is  irritating  to  the  tissues  and 
more  poisonous  than  cocain;  nirvanin  possesses  little  anesthetic  value; 
alypin  and  stovain  are  closely  related.  Both  are  slightly  acid  in 
reaction,  produce  pain  when  injected,  and  occasionally  necrosis. 


LOCAL  ANESTHETICS  509 

According  to  Le  Brocq,  the  toxicity  of  these  chemicals  may  be 
expressed  as  follows :  if  the  toxicity  of  cocain  is  taken  as  the  standard 
and  expressed  as  1,  then  that  of  alypin  will  represent  1.25;  nirvanin, 
0.714;  stovain,  0.625;  tropacocain,  0.5;  novocain,  0.49;  eucain  B,  0.414. 

Novocain  alone  fully  corresponds  to  every  one  of  the  above  claims. 
Its  toxicity  is  about  six  times  less  than  cocain;  it  does  not  irritate 
in  the  slightest  degree  when  injected,  consequently  no  pain  is  felt 
from  its  injection  2^^^  se;  it  is  soluble  in  its  own  weight  of  water;  it 
will  combine  with  epinephrin  in  any  proportion  without  interfering 
with  the  physiologic  action  of  the  latter,  and  it  will  be  absorbed  readily 
by  the  mucous  membrane.  The  studies  of  Biberfield  and  Braun 
brought  to  light  another  extremely  interesting  fact  concerning  the 
novocain-epinephrin  combination.  Both  experimenters,  working  inde- 
pendently of  each  other,  observed  that  epinephrin  anemia  on  the  one 
hand,  and  the  novocain  anesthesia  on  the  other  hand  were  markedly 
increased  in  their  total  effects  upon  the  tissues.  Consequently,  a 
smaller  quantity  of  this  most  happy  combination  is  required  to  pro- 
duce the  same  therapeutic  effect  as  a  large  dose  of  each  individual 
drug  would  produce  when  injected  separately. 

Novocain. — Novocain  (procain)  is  the  hydrochloric  salt  of  a  syn- 
thetically prepared  alkaloid,  the  methyl  ester  of  a  p-amino-benzoic 
acid.  It  is  a  white  crystalline  powder  melting  at  263°  F,  (150°  C). 
It  may  be  heated  to  200°  F.  (120°  C.)  without  decomposition.  It  dis- 
solves in  an  equal  amount  of  cold  water,  the  solution  having  a  neutral 
character;  in  cold  alcohol  it  dissolves  in  the  proportion  of  1  to  30. 
Caustic  alkalies  and  alkaline  carbonates  precipitate  the  free  base  from 
the  aqueous  solution  in  the  form  of  a  colorless  oil,  which  soon  solidifies. 
It  is  incompatible  with  the  alkalies  and  alkaline  carbonates,  with  picric 
acid  and  the  iodids.  Its  solutions  may  be  sterilized  by  boiling  without 
decomposition. 

As  stated  above,  the  relative  toxicity  of  a  given  quantity  of  cocain 
in  solution  depends  upon  its  concentration;  this  same  peculiarity  is 
not  shared  by  novocain.  The  dose  of  novocain  may  be  fixed  safely  at 
one-third  of  a  grain  for  a  single  injection.  For  dental  purposes  a  1| 
or  2  per  cent,  solution  in  combination  with  epinephrin  has  been  injected 
without  any  ill  results.  On  account  of  its  pow^erful  vasoconstrictor 
action,  the  addition  of  epinephrin  in  small  doses  is  well  suited  to  the 
purpose  of  confining  the  injected  novocain  to  a  given  area.  It  is  the 
important  factor  which  prevents  the  ready  absorption  of  both  drugs, 
and  consequently  largely  nullifies  poisonous  results.  An  injection  of 
10  drops  of  a  2  per  cent,  solution  of  novocain  labially  into  the  tissue 
produces  a  diffuse  anesthesia  lasting  approximately  twenty  minutes; 
the  same  quantity,  with   the  addition  of    one    drop  of  epinephrin 


510 


LOCAL  ANESTHESIA 


chlorid  solution,  increases  the  anesthetic  period  to  over  one  hour,  and 
locaHzes  the  effect  upon  the  injected  area. 

A  suitable  solution  of  novocain  for  dental  purposes  may  be  prepared 
as  follows: 

Novocain 10  gr.  (0.60  gm.) 

Sodium  chlorid 4  gr.  (0.25  gm.) 

Distilled  water 1  fl.  oz.  (30.00  c.c.) 

Boil. 

To  each  cubic  centimeter  add  one  drop  of  epinephrin  solution  when  used. 

A  sterile  solution  may  be  made  extemporaneously  by  dissolving  the 
necessary  amount  of  novocain-epinephrin  in  tablet  form  in  a  given 
quantity  of  boiling  physiologic  salt  solution.  A  suitable  tablet  may  be 
prepared  as  follows: 


Novocain      .... 
Suprarenin  hydrochlorid 


gr. 


(0.015  gm.) 
(0.000054  gm.) 


One  tablet  dissolved  in  20  minims  (1  c.c.)  of  boiling  physiologic  salt 
solution  makes  a  1|  per  cent,  solution  of  novocain  ready  for  imme- 
diate use. 

Solutions  for  hypodermic  purposes  should  be  made  fresh  when 
needed.  A  simple  porcelain  crucible  or  a  graduated  porcelain  dissolv- 
ing cup  held  by  a  suitable  twisted  aluminum 
tongue  and  a  dropping  bottle  constitute  a 
simple  outfit  for  this  work.  The  dropping 
bottle  should  hold  about  4  ounces  and  should 
be  provided  with  a  dust  cap.  A  groove  on  one 
side  of  the  neck  of  the  bottle,  and  a  vent  on  the 
other  connected  with  two  grooves  in  the  back  of 
the  stopper  allow  the  contents  to  flow  drop  by 
drop.  A  quarter  turn  of  the  stopper  closes 
the  bottle  tightly.  The  number  of  drops  pres- 
ent in  each  cubic  centimeter  differs  with  the 
various  sizes  of  the  dropping  bottle,  hence  each 
bottle  has  to  be  standardized  with  a  tested 
minim  graduate  or  a  tested  burette.  The 
standardized  number  may  be  marked  on  the 
respective  bottles  with  a  carborundum  stone. 

Hypodermic  Armamentarium.^ — A  hypodermic 
s;yTinge  that  answers  all  dental  purposes  equally 
well  is  an  important  factor  in  carrying  out  the 
correct  technic  of  the  injection.  The  injection 
into  the  dense  gum  tissue  often  requires  10  or 
more  pounds  of  pressure  as  registered  by  an 
interposed  dynamometer,  while  in  pressure  anesthesia  even  greater 
pressure  is  frequently  applied. 


Fig.  409. — Dropping 
bottle. 


LOCAL  ANESTHETICS  511 

The  selection  of  a  suitable  hypodermic  syringe  is  largely  a  matter 
of  choice.  All-glass  syringes,  glass-barrel  syringes,  and  all-metal 
syringes  are  the  usual  types  found  in  the  market.  An  all-glass  syringe 
that  answers  every  reasonable  demand  regarding  asepsis,  durability, 
and  perfect  construction,  and  that  is  giving  universal  satisfaction,  has 
been  brought  out  recently  by  the  S.  S.  White  Dental  Manufacturing 
Company.  The  syringe  is  constructed  after  the  well  known  Luer 
pattern,  holding  1^  c.c.  and  it  is  marked  with  suitable  divisions  on  the 
barrel.  The  piston  and  the  barrel  are  ground  so  perfectly  that  no 
washers  are  required  to  make  water-tight  joints.  An  adjustable  finger 
rest  is  easily  slipped  over  the  assembled  parts  which  greatly  assists  in 
adjusting  the  needle-opening  in  any  desired  direction  and  in  exerting 
pressure  on  the  piston.  The  piston-rod,  made  of  solid  glass,  is  suffi- 
ciently long  to  allow  about  two  inches  of  space  between  the  finger  rest 
and  the  piston  top.  This  space  is  of  importance,  as  it  allows  the  last 
drop  of  fluid  to  be  expelled  under  pressure  without  tiring  the  fingers. 
A  removable  cane-handle,  made  of  metal,  greatly  facilitates  the  exer- 
tion of  pressure  on  the  piston.  The  needle-adapter  carries  a  universal 
thread  so  as  to  accommodate  the  hub  of  the  ordinary  hypodermic 
needles.  The  various  parts  of  the  syringe  may  be  detached  in  a  few 
moments  to  allow  sterilization  by  boiling. 

Glass-barrel  syringes  are  not  to  be  recommended  for  dental  purposes, 
as  they  are  too  troublesome  to  keep  in  order.  After  carefully  testing 
most  of  the  metal  hypodermic  syringes  offered  in  the  markets  within 
the  last  ten  years,  by  means  of  the  pressure  gauge  and  in  clinical  work 
subjecting  them  to  a  routine  wear,  the  author  has  found  that  the 
syringes  of  the  so-called  "Imperial"  type  are  to  be  preferred  over  other 
makes.  They  are  usually  made  of  nickel-plated  brass  which,  however, 
is  a  disadvantage,  as  the  nickel  quickly  wears  off  from  the  piston,  and 
exposes  easily  corroded  brass.  The  piston  should  preferably  be  made 
of  pure  German  silver.  An  all-metal  syringe  as  pictured  in  Fig.  410 
gives  good  results  in  heavy  pressure  work  and  can  be  recommended. 
The  syringe  holds  40  minims  (2  c.c),  is  provided  with  a  strong  finger 
crossbar,  and  is  extremely  simple  in  construction.  The  piston  consists 
of  a  plain  metal  rod,  without  a  thickened  or  ground  piston-end  or 
packing.  The  packing  consists  of  leather  washers  inserted  at  the 
screw-joint,  and  is  quickly  removed  and  replaced  if  necessary. 

The  hypodermic  syringe  requires  careful  attention.  It  is  not  neces- 
sary to  sterilize  it  by  boiling  after  each  use,  unless  it  should  be  con- 
taminated with  blood  or  pus.  The  simple  repeated  washings  with  a 
mixture  of  one  part  of  glycerin  and  seven  parts  of  alcohol  and  careful 
drying  are  sufficient.  The  cap  should  be  readjusted,,  and  the  piston 
rod  covered  with  a  thin  carbolated  vaselin  or  sm-gical  lubricating  jelly 


512 


LOCAL  ANESTHESIA 


and  placed  in  position.  If  the  syringe  be  boiled,  all  the  washers  must 
be  removed.  The  syringe  is  best  kept  in  a  covered  glass  or  metal  case; 
a  large  bacteriologic  Petri  dish  is  suitable  for  this  purpose.  Leather- 
lined  or  felt-lined  boxes  afford  breeding  places  for  bacteria,  and  should 


Fig.  410. — Metal  syringe. 

not  be  used.  Some  operators  prefer  to  keep  their  syringes  constantly 
in  the  above  mentioned  glycerin-alcohol  solution  when  not  in  use,  and 
others  prefer  to  place  them  in  a  special  sterilizing  jar  which  may  now 
be  purchased  in  the  market. 


LOCAL  ANESTHETICS 


513 


Dental  h>']Dodermic  needles  should  be  made  preferably  of  seamless 
steel,  or  still  better,  of  vanadimn  steel,  24  to  26  B  and  S  gauge  and 
proA'ided  with  a  short  razor  edge  point.  Thicker  needles  cause  unneces- 
sary pain,  and  thinner  needles  are  liable  to  break.  Iridio-platinum 
needles  are  preferred  by  some  operators,  as  they  may  be  readily  steril- 
ized in  an  open  flame.  The  needle  should  measure  from  a  half  to  one 
inch.     For  infiltration  or  conduction  anesthesia  one  and   a  half -inch 


Fig.  411. — Hood's  sterilizing  jar. 


needles  are  necessary  and  cm'ved  attachments  of  various  shapes  are 
essential  in  reachmg  the  posterior  parts  of  the  mouth.  The  "Schim- 
mel""  needles  are  excellent,  but  do  not  fit  every  syringe.  For  pressure 
anesthesia  special  needles  are  required,  and  may  be  bought  or  quickly 
prepared  by  grmdmg  oft'  the  steel  needle  at  its  point  of  reinforcement. 
The  sterile  needle  should  be  kept  in  well-protected  glass  contamers. 
The  needles  are  sterilized  after  each  use  by  boiling  in  plain  water, 
dried  with   the  hot   air   s^Tino;e.  and   immediateh'  transferred   to  a 


514  LOCAL  ANESTHESIA 

covered  sterile  glass  dish.  The  dried  sterile  needles  should  not  be 
touched  again  with  the  fingers,  and  the  customary  wire  insertion  is 
unnecessary. 

TECHNIC  OF  THE  INJECTION. 

Various  methods  of  injecting  solution  about  the  teeth  are  in  vogue. 
For  the  sake  of  convenience,  we  may  be  permitted  to  divide  them  as 
follows : 

1.  Terminal  anesthesia: 

Subperiosteal  injection. 
Peridental  injection. 

2.  Conduction  anesthesia. 

Injection  at  the  infra-orbital  foramen. 
Injection  at  the  maxillary  tuberositj^ 
Injection  at  the  incisive  foramen. 
Injection  at  the  posterior  palatine  foramen. 
Injection  at  the  mandibular  foramen. 
Injection  at  the  mental  foramen. 

3.  Pulp  anesthesia. 

Before  starting  any  surgical  interference  in  the  mouth,  the  field  of 
operation  should  be  thoroughly  cleansed  and  sterilized  by  painting 
with  diluted  tincture  of  iodin.  A  serviceable  dilution  of  the  tincture 
for  such  purposes  is  made  as  follows: 

Tinctiire  of  iodin  (U.  S.  P.) ^  oz.         (15  c.c.) 

Aceton 1    oz.         (30  c.c.) 

Keep  in  glass-stoppered  bottles  and  apply  with  a  cotton  swab. 

After  the  diagnosis  is  made  the  method  of  injection  best  suited  for 
the  case  in  hand  is  decided  upon.  The  required  quantity  and  concen- 
tration of  the  anesthetic  solution  is  now  prepared  and  the  syringe  a  ad 
hypodermic  needle  fitted  ready  for  the  work.  The  correct  position 
of  the  syringe  in  the  hand  of  the  operator  and  its  proper  manipula- 
tion are  important  factors  which  are  acquired  by  practice.  The  hand 
holding  the  syringe  is  governed  exclusively  in  its  movement  by  the 
wrist,  so  as  to  allow  delicate  and  steady  movements,  and  the  fingers 
must  be  trained  to  a  highly  developed  sense  of  touch.  The  syringe  is 
filled  by  drawing  the  solution  up  into  it;  it  is  held  perpendicularly, 
point  up,  and  the  piston  is  pushed  upward  until  the  first  drop  appears 
at  the  needle  point,  which  precaution  prevents  the  injection  of  air  into 
the  tissues. 

The  Subperiosteal  Injection.- — ^The  subperiosteal  injection  about  the 
root  of  an  anterior  tooth  is  best  started  by  inserting  the  needle  midway 
between  the  gingival  margin  and  the  approximate  location  of  the  apex. 


TECHNIC  OF  THE  INJECTION  515 

The  pain  of  the  first  puncture  may  be  obviated  by  using  a  fine,  very 
sharp-pointed  needle,  by  the  simple  compression  of  the  gum  tissue 
with  the  finger  tip  or  by  holding  a  pledget  of  cotton  saturated  with  the 
prepared  anesthetic  solution  on  the  gum  tissue  for  a  few  moments. 
The  needle  opening  faces  the  bone,  the  syringe  is  held  in  the  right  hand 
at  an  acute  angle  with  the  long  axis  of  the  tooth,  while  the  fingers 
of  the  left  hand  hold  the  lip  and  cheek  out  of  the  way.  After  punc- 
turing the  mucosa,  a  drop  of  the  liquid  is  at  once  deposited  in  the  tissue, 
and  the  further  injection  is  painless.  Slowly  and  steadily  the  needle  is 
forced  through  the  gum  tissue  and  periosteum  along  the  alveolar  bone 
toward  the  apex  of  the  tooth,  depositing  the  fluid  under  pressure  close 
to  the  bone  on  its  upw^ard  and  return  trip.  The  continuous  slow  moving 
of  the  needle  prevents  injecting  into  a  vein.  A  second  injection  may  be 
made  by  partially  withdrawing  the  needle  from  the  puncture  ard 
swinging  the  syringe  anteriorly  or  posteriorly,  as  the  case  may  be,  from 
the  first  route  of  the  injection.  This  latter  method  is  especially  indi- 
cated in  injecting  the  upper  molars.  After  removing  the  needle,  place 
the  finger  tip  over  the  puncture  and  slightly  massage  the  injected  area. 
A  circular  elevation  outlines  the  injected  field.  The  naturally  pink 
color  of  the  gum  will  shortly  change  to  an  anemic  hue,  indicating  the 
physiologic  action  of  the  epinephrin  on  the  circulation.  No  wheal 
should  be  raised  by  the  fluid,  as  that  would  indicate  superficial  infil- 
tration and  consequently  failure  of  the  anesthetic. 

As  the  liquid  requires  a  definite  length  of  time  to  pass  through  the 
lamina  of  bone  so  as  to  reach  the  nerves  of  the  peridental  membrane 
and  the  pulp,  from  five  to  ten  minutes  should  be  allowed  before  the 
extraction  is  started.  The  length  of  time  depends  on  the  density  of 
the  surrounding  bony  structure  of  the  tooth.  The  progress  of  the 
anesthesia  may  be  tested  with  a  fine  pointed  probe,  and  its  complete- 
ness indicates  the  time  when  the  extraction  should  be  started. 

The  upper  eight  anterior  teeth  usually  require  a  labial  and  a  lingual 
injection;  the  molars  require  both  a  buccal  and  a  lingual  injection. 
Buccally  the  injection  should  be  made  midway  between  the  mesial 
and  distal  root,  and  on  the  lingual  side  over  the  lingual  root. 

The  lower  eight  anterior  teeth  are  comparatively  easily  reached 
by  the  injection.  The  needle  is  inserted  near  the  apices  of  the  teeth, 
the  syringe  is  held  in  a  horizontal  position,  and  the  injection  may  be 
made  as  previously  outlined. 

The  lower  molars  require  a  buccal  and  a  lingual  injection.  The 
needle  is  inserted  into  the  gum  margin,  midway  between  the  roots  and 
the  apices.  The  external  and  internal  oblique  line  materially  hinders 
the  ready  penetration  of  the  injected  fluid,  and  therefore  ample  time 
should  be  allowed  for  its  absorption. 


516  LOCAL  ANESTHESIA 

If  two  or  more  adjacent  teeth  are  to  be  removed,  the  injection  by 
means  of  infiltrating  the  area  near  the  gum  fold  directly  over  the 
apices  of  the  teeth  is  to  be  preferred.  It  is  advisable  to  use  a  one  inch 
needle  for  this  purpose,  holding  the  syringe  in  a  horizontal  position, 
so  as  to  reach  a  large  field  with  a  single  injection. 

The  injection  into  inflamed  tissue,  into  an  abscess,  and  into  phleg- 
monous infihration  about  the  teeth  is  to  be  avoided.  The  injection 
into  engorged  tissue  is  very  painful;  the  dilated  vessels  quickly  absorb 
the  anesthetic  without  producing  complete  anesthesia,  and  general 
poisoning  may  result.  In  purulent  conditions  an  injection  is  decidedly 
dangerous,  as  it  forces  the  existing  infection  beyond  the  line  of  demar- 
cation. If  the  abscess  presents  a  definite  outline,  the  injection  should 
be  made  into  the  sound  tissue  surrounding  its  focus.  If  a  tooth  is 
affected  with  acute  diffuse  or  suppurating  pericementitis,  a  distal  and 
a  mesial  injection  usually  produce  successful  anesthesia  by  blocking 
the  sensory  nerve  fibers  in  all  directions. 

PERIDENTAL  ANESTHESIA. 

Teeth  or  roots  standing  singly,  or  teeth  affected  by  pyorrhea  or 
similar  chronic  peridental  disturbances,  are  frequently  anesthetized 
quickly  and  satisfactorily  by  injecting  the  anesthetic  solution  directly 
into  the  peridental  membrane.  This  method  is  known  as  peridental  an- 
esthesia and  its  technic  is  very  simple.  In  single-rooted  teeth  the  short 
hypodermic  needle  is  inserted  under  the  free  margin  of  the  gum,  or 
through  the  interproximate  papilla,  into  the  pericemental  membrane 
between  the  tooth  and  the  alveolar  process.  At  times  the  needle  may  be 
forced  through  the  thin  lamella  of  bone  so  as  to  reach  the  peridental  mem- 
brane directly.  To  gain  access  to  this  membrane  in  teeth  set  close 
together,  slight  separation  with  an  orange-wood  stick  or  other  suitable 
means  is  often  found  to  be  of  advantage.  Two  and  sometimes  three 
injections  are  necessary.  To  force  the  liquid  into  the  peridental  mem- 
brane usually  requires  a  higher  pressure  than  that  which  is  necessary  for 
injecting  the  periosteum  covering  the  alveolar  process,  but  the  quantity 
of  the  anesthetic  liquid  used  is  less  than  that  which  is  required  for  the 
former  injection.  Acute  inflammatory  conditions  of  the  peridental 
membrane  and  its  sequelae  prohibit  the  use  of  this  method.  Peridental 
anesthesia  is  the  purest  form  of  local  anesthesia,  since  the  seat  of  the 
nerve  supply  of  the  tooth  is  very  quickly  reached,' and  as  a  consequence 
the  results  obtained  are  in  the  majority  of  cases  extremely  satisfactory, 
provided  that  general  conditions  justify  its  application. 

Injection  at  the  Infra-orbital  Foramen. — ^To  reach  the  nerve  plexus 
which  passes  through  the  infra-orbital  foramen  and  furnishes  inner- 


PERIDENTAL  ANESTHESIA  517 

vation  to  the  upper  incisors  and  cuspids,  an  injection  is  readily 
made  in  this  region  and  it  is  always  followed  by  the  desired  results. 
The  infra-orbital  foramen  is  easily  located  about  one-quarter  inch 
below  the  middle  of  the  inferior  ridge  of  the  orbit  by  palpating  with 
the  index  finger  of  the  left  hand.  The  lip  is  drawn  up  with  the  thumb 
of  the  same  hand  and  the  one  and  a  half  inch  needle  is  inserted  into 
the  gum  fold  between  the  cuspid  and  the  first  bicuspid  teeth.  Slowly 
the  needle  is  forced  upward  along  the  surface  of  the  bone,  injecting 
a  few  drops  of  fluid  on  its  way  until  the  needle  point  is  felt  under  the 
ball  of  the  compressing  finger  resting  over  the  foramen.  The  syringe 
is  now  slowly  emptied  and  withdrawn. 

After  the  injection,  slight  massage  is  advantageous  in  every  case. 
To  reach  those  branches  of  the  anterior  superior  dental  nerve  which 
enter  into  the  body  of  the  maxillary  bone,  a  good  sized  cotton  tampon 


Fig.  412. — ^Average  range  of  anesthesia  after  an  injection  about  the  infra-orbital  foramen. 

saturated  with  a  20  per  cent,  solution  of  novocain  in  distilled  water  is 
placed  in  the  lower  meatus  of  the  nose  and  left  there  during  the  oper- 
ation. A  few  drops  of  the  anesthetic  solution  injected  about  the 
marginal  gum  tissues  of  the  tooth  or  teeth  under  consideration  will 
materially  assist  in  obtaining  complete  anesthesia. 

Injection  at  the  Maxillary  Tuberosity. — ^To  reach  the  posterior  superior 
dental  nerves  which  pass  through  numerous  small  foramina  at  the 
surface  of  the  tuberosity  the  syringe  mounted  with  a  long  needle  and 
held  at  an  acute  angle  is  introduced  into  the  half-opened  mouth  and 
inserted  high  up  near  the  reflection  of  the  mucous  membrane  within 
the  region  of  the  second  molar.  The  needle,  lying  close  to  the  bone  is 
pushed  slowly  backward,  upward  and  inward  and  simultaneously 
about  1  to  1|  c.c.  of  the  solution  is  slowly  injected. 

In  many  instances  the  lower  border  of  the  spheno-maxillary  fossa 
is  reached  which  materially  assists  in  the  dissemination  of  the  fluid 


518  LOCAL  ANESTHESIA 

within  the  vicinity  of  the  foramen  rotundum  through  which  the  second 
division  of  the  fifth  nerve  passes. 

Injection  at  the  Incisive  Foramen. — ^The  nasopalatine  nerves  pass 
through  the  foramina  of  Scarpa  (incisive  foramen)  which  are  located 


Fig.  413. — Average  range  of  anesthesia  after  an  injection  about  the  posterior  dental  canal. 

(Maxillary  tuberosity.) 

within  the  suture  of  the  maxillary  bones.  If  an  imaginary  line  passing 
over  the  hard  palate  is  drawn  from  the  distal  borders  of  the  two  cuspids, 
the  line  will  ordinarily  pass  through  the  foramina.  If  the  needle  is 
inserted  into  the  papilla  directly  back  of  the  two  upper  central  incisors, 
on  its  upward  course  it  will  pass  directly  into  the  foramen.    Eight  to 


Fig.  414. — Average  range  of  anesthesia  after  an  injection  about  the  incisive  foramen. 

ten  drops  of  the  solution  slowly  injected  are  usually  followed  by  intense 
blanching  of  the  anterior  palate. 

Injection  at  the  Posterior  Palatine  Foramen. — ^The  posterior  palatine 
foramen  is  usually  easily  recognized  by  a  slight  depression  in  the 


PERIDENTAL  ANESTHESIA  519 

mucous  membrane  about  one-half  inch  above  the  border  of  the  alveolar 
process  near  the  last  erupted  molar.  The  short  needle  is  inserted  in 
advance  of  the  depression  and  gently  pushed  backward  and  upward; 
about  eight  to  ten  drops  of  the  solution  are  injected. 


Fig.  415. — Average  range  of  anesthesia  after  an  injection  about  the  posterior  palatine 

foramen. 

Injection   at  the   Mandibular   Foramen. — ^The   successful   anestheti- 
zation of  the  lower  molars  by  the  subperiosteal  injection  is  frequently 


Fig.  416. — Average  range  of  anesthesia  after  an  injection  about  the  mandibular  fora- 
men. The  shaded  area  is  innervated  by  fibers  of  the  buccal  nerve  and  requires  an 
additional  subperiosteal  injection  within  that  region. 

fraught  with  many  difficulties  on  account  of  the  h.esi\y  bony  ridges 
on  both  sides  of  the  teeth,  which  form  strong  barriers  to  the  ready 
penetration  of  the  solution  into  the  bone.  To  overcome  these  difficulties 
Braun,  in  1905,  introduced  a  method,  originally  suggested  by  Halstead, 


520  LOCAL  ANESTHESIA 

in  1885.  of  centrally  anesthetizing  the  mandibular  and,  incidentally, 
in  many  instances,  the  lingual  nerve  near  the  region  of  the  mandibular 
foramen. 

By  palpating  the  surface  of  the  ramus  in  the  open  mouth  with  the 
finger,  the  anterior  sharp  border  of  the  coronoid  process  is  easily  felt 
about  three-quarters  of  an  inch  posterior  of  the  third  molar.  The 
process  passes  downward  along  the  side  of  the  last  molar,  and  loses 
itself  in  the  external  oblique  line.  Mesially  from  this  ridge  is  to  be 
found  a  small  triangular  concave  fossa,  which  faces  downward  and 
outward,  bounded  lingually  by  the  internal  oblique  line  and  covered 
with  mucous  membrane.  As  there  is  no  anatomic  name  attached  to 
this  space,  Braun  has  called  it  the  retromolar  triangle.  Immediately 
back  of  the  lingual  border  of  this  triangle,  directly  beneath  the  mucous 
membrane,  lies  the  lingual  nerve,  and  about  three-eighths  of  an  inch 
farther  back  the  mandibular  nerve.  This  last  nerve  lies  close  to  the 
bone,  and  enters  into  the  mandibular  foramen  which  is  located  at  the 
lower  border  of  the  mandibular  sulcus  and  is  partially  covered  by 
the  mandibular  spine  or  lingula. 

Before  starting  the  injection  the  patient  should  be  cautioned  to  rest 
his  head  quietly  on  the  head-rest  of  the  chair,  as  any  sudden  movement 
or  interference  with  the  hand  of  the  operator  may  be  the  cause  of 
breaking  the  needle  in  the  tissues. 

The  syringe  is  provided  with  a  one  and  a  half  inch  needle,  held  in  a 
horizontal  position  and  placed  in  the  half  open  mouth  across  the  tongue 
in  the  direction  of  the  internal  oblique  line  of  the  ramus.  The  needle 
opening  faces  the  bone.  The  body  of  the  syringe  should  rest  between 
the  cuspid,  lateral  incisor,  or  bicuspid,  as  the  case  may  be.  The 
thumb  or  the  index  finger  of  the  left  hand  should  be  employed  for 
palpating  the  retromolar  triangle  and  the  nail  edge  should  be  placed 
directly  over  the  border  of  the  internal  oblique  line.  This  point  marks 
the  place  for  the  insertion  of  the  needle.  The  beginner  usually  selects 
a  point  too  far  mesially.  At  the  moment  of  inserting  the  needle,  the 
nail  of  the  finger  is  withdrawn  and  the  needle  strikes  the  bone  directly 
beneath  the  mucous  membrane  about  one-half  inch  above  the  occlud- 
ing surface  of  the  last  molar.  The  needle  should  be  slowly  advanced 
along  the  surface  of  the  bone  and  at  the  same  time  the  syringe  should 
be  swung  gradually  toward  the  other  side  of  the  mandible  so  as  to 
rest  upon  the  occluding  surfaces  of  the  teeth.  The  touch  of  the  bony 
surface  of  the  ramus  which  had  been  lost  for  a  few  moments,  is  again 
felt  and  the  needle  steadily  advances  in  the  direction  of  the  mandi- 
bular spine.  From  now  on,  the  touch  with  the  bone  must  never  be 
lost.  About  I  c.c.  of  the  anesthetic  solution  should  be  injected  on 
its  way  to  the  sulcus  and  about  1|  c.c.  deposited  under  steady  backward 


PERIDENTAL  ANESTHESIA 


521 


and  forward  motion  of  the  needle  within  the  region  of  the  manthbular 
fossa.  From  fifteen  to  twenty  minutes  are  usually  required  for  the 
anesthetization  of  the  mandibular  nerve.  A  slight  infiltration  of  the 
gum  tissue  about  the  teeth  to  be  operated  upon  insures  a  painless 
operation.  Injection  at  the  mandibular  foramen  is  possible  only 
when  the  patient  can  open  the  mouth  sufficiently  to  allow  the  ready 
introduction  of  the  syringe.  If  the  tissues  about  the  third  molar  are 
infiltrated  with  inflammatory  exudates,  local  anesthesia  is  absolutely 
prohibited. 

Conduction  anesthesia  of  the  mandible  is  serviceable  if  a  number  of 
teeth  are  to  be  removed  at  one  sitting.  It  should  be  borne  in  mind, 
however,  that  in  general  only  one-half  of  either  jaw  should  be  anes- 
thetized at  one  sitting,  so  as  to  keep  the  quantity  of  the  injected 
anesthetic  solution  within  the  limits  of  ordinary  dosage. 


Fig.  417. — -Average  range  of  anesthesia  after  an  injection  about  each  of  the  mental 

foramina. 

Injection  at  the  Mental  Foramen. — ^The  mental  foramen  is  usually 
easily  located  by  exerting  slight  pressure  near  the  apices  of  the  first 
and  second  bicuspids  upon  the  buccal  surface  of  the  mandible.  The 
needle  should  be  inserted  in  this  region  holding  the  syringe  in  a  per- 
pendicular position  pointing  dowai-ward.  The  finger  tip  should  be 
placed  over  the  foramen  to  act  as  a  guide  to  the  needle  in  its  slightly 
forward  and  downward  course.  About  ten  to  tweh^e  drops  should  be 
injected  and  slight  pressure  exerted  by  the  finger  which  will  assist  in 
the  passage  through  the  foramen  into  the  mandible. 

Pulp  Anesthesia,^ — By  pressure  anesthesia,  pressure  cataphoresis, 
pulp  anesthesia,  or  contact  anesthesia,  as  this  process  is  variously 
termed,  we  understand  the  introduction  of  an  anesthetizing  agent  in 

1  The  omission  of  a  discussion  of  the  use  of  arsenic  for  pulp  devitalization  should  not 
be  interpreted  to  be  a  condemnation  of  this  drug. 


522  LOCAL  ANESTHESIA 

solution  by  mechanical  or  electric  force  through  the  dentin  into  the 
pulp  or  directly  into  the  exposed  pulp  for  the  purpose  of  rendering  this 
latter  organ  insensible  to  pain.  Simple  hand  pressure  with  the  finger  or 
with  a  suitably  shaped  instrument,  with  the  hypodermic  syringe  or  with 
the  so-called  high  pressure  syringe,  is  recommended  for  such  purposes. 

Before  describing  the  modus  operandi  of  the  various  methods,  the 
histologic  structure  of  the  dentin  should  be  recalled  briefly.  Dentin 
is  made  up  of  about  72  per  cent,  inorganic  salts,  about  10  per  cent,  water 
and  an  organic  matrix  constituting  the  remaining  per  cent.  The  dentin 
is  traversed  by  a  large  number  of  more  or  less  wave-like  tubuli,  radiat- 
ing from  the  pulp  cavity  toward  the  periphery,  where  they  branch  off, 
forming  a  deltoid  network.  Roemer  has  counted  about  30,000  dentinal 
tubuli  within  the  area  of  a  square  millimeter.  These  tubuli  are  filled 
with  processes  of  the  odontoblasts,  known  at  present  as  "Tomes" 
fibers,  and  they  are  concerned  with  the  metabolic  changes  occurring 
in  the  dentin.  The  dentinal  fibrils  are  protoplasmic  in  their  nature  and 
normally  do  not  carry  physiologic  sensation  in  the  sense  we  under- 
stand this  term.  We  can  cut,  file,  or  otherwise  injure  the  sound  dentin 
without  much  inconvenience  to  the  patient.  When  the  fibers  have 
become  highly  irritated,  a  mere  touch  upon  the  dentin  may  at  once  call 
forth  a  paroxysm  of  pain. 

1.  When  the  Pulp  is  Exposed  or  Covered  with  a  Layer  of  Decalcified 
Dentin. — Isolate  the  tooth  with  the  rubber  dam,  and  clean  it  with 
water.  Excavate  the  cavity  as  much  as  possible,  and,  if  the  pulp  is 
not  fully  exposed,  wipe  out  the  cavity  with  chloroform  to  remove 
fatty  deposits  from  the  cartilaginous  layer  of  dentin,  and  dehydrate 
with  absolute  alcohol  and  warm  air.  Saturate  a  small  pledget  of  cotton 
with  a  warm  concentrated  novocain  solution  in  sterile  water,  carry  it 
into  the  prepared  cavity  and  cover  it  with  a  large  pledget  of  cotton,  and 
then,  with  a  piece  of  slightly  warmed  unvulcanized  rubber  which  should 
completely  fill  the  cavity,  and  with  a  broad-faced  amalgam  plugger  or 
some  other  suitably  shaped  instrument,  apply  slowly,  increasing  pres- 
sure from  one  to  three  minutes.  The  pulp  may  now  be  fully  exposed 
and  tested.  If  it  is  still  sensitive,  repeat  the  process.  Loefiler  states: 
"This  pressure  may  be  applied  by  taking  a  short  piece  of  orange  wood, 
fit  it  into  the  cavity  as  prepared,  and  direct  the  patient  to  bite  down 
upon  this  with  increasing  force.  In  this  way  we  can  obtain  a  well- 
directed  regulated  force  or  pressure,  and  with  less  discomfort  to  the 
patient  and  the  operator."  Miller  describes  his  method  as  follows: 
"After  excavating  the  cavity  as  far  as  convenient  and  smoothing  the 
borders  of  it,  take  an  impression  in  modelling  compound,  endeavoring 
to  get  the  margins  of  the  cavity  fairly  well  brought  out;  put  a  few 
threads  of  cotton  into  the  cavity  and  saturate  them  thoroughly  with 


PERIDENTAL  ANESTHESIA 


523 


a  5  to  10  per  cent,  solution  of  novocain,  cover  this  with  a  small  bit  of 
rubber  dam,  and  then  press  the  compound  impression  down  upon  it. 
A  perfect  closure  of  the  margin  may  thereby  be  obtained,  so  that  the 
liquid  cannot  escape,  and  one  can  then  exert  pressure  with  the  thumb 
sufficient  to  press  the  solution  into  the  dentin."  Instead  of  novocain 
solution,  a  so-called  novocain  "pluglet"  may  be  used.  A  pluglet  is 
introduced  into  the  cavity  covered  with  a  wisp  of  cotton  dipped  in 
sterile  water  and  the  further  procedure  is  precisely  the  same  as  des- 
cribed above. 

2.  When  the  Pulp  is  Covered  with  a  Thick  Layer  of  Healthy  Dentin. — 
With  a  very  small  bibeveled  drill  bore  through  the  enamel  or  directly 
into  the  exposed  dentin  at  a  convenient  place,  guiding  the  drill  in  the 
direction  of  the  pulp  chamber.    Blow  out  the  chips,  dehydrate  with 


Fig.  418 


alcohol  and  warm  air  and  apply  the  hypodermic  or  high  pressure 
syringe,  provided  with  a  special  needle,  making  as  nearly  as  possible 
a  water-tight  joint.  Apply  slow,  continuous  pressure  for  two  or  three 
minutes.  With  a  bur  the  pulp  should  now  be  exposed,  and,  if  still 
found  sensitive,  the  process  should  be  repeated.  As  an  anesthetic  for 
this  purpose  a  5  or  10  per  cent,  solution  of  novocain  in  sterile  water  is 
recommended.  Or  a  wisp  of  cotton  saturated  with  the  same  solution 
or  a  moistened  novocain  pluglet  may  be  placed  in  the  hole,  and  then 
covered  with  an  instrument  that  will  just  about  fit  into  the  opening. 
Slight  pressure  should  then  be  exerted. 

Within  recent  years  a  number  of  complicated  syringes,  variously 
known  as  high  pressure  syringes  or  obtunders,  have  been  advocated. 
Their  mechanism  is  based  upon  the  conception  of  forcing  anesthetic 
solutions  through  sound  tooth  substance  by  high  pressure.     Close 


524  LOCAL  ANESTHESIA 

contact  of  the  anesthetic  fluid  with  the  dentinal  fibers,  plus  the  neces- 
sary time  for  conveying  the  absorbed  anesthetic  via  the  Tomes'  fibers 
to  the  nerve  endings  in  the  pulp,  explains  the  phenomenon  very  plaus- 
ibly. A  strong  metal  syringe,  provided  with  an  especially  prepared 
needle  to  make  as  nearly  as  possible  a  water-tight  joint,  is  all  that  is 
required.  Those  who  prefer  a  special  high  pressure  syringe  for  such 
purposes  may  purchase  any  one  of  the  many  devices  that  will  suit 
their  fancy.  The  Weaver  obtunder  and  the  Jewett-Willcox  syringe 
are  much  lauded  for  such  purposes. 

Any  one  of  the  various  methods  for  anesthetizing  a  tooth  as  outlined 
in  the  preceding  discussion  may  also  be  used  for  anesthetizing  the  pulp. 

In  teeth  not  fully  decalcified  and  in  so-called  "soft"  teeth,  pressure 
anesthesia  produces  most  satisfactory  results,  while  the  process  fails 
in  teeth  of  old  persons,  teeth  of  inveterate  tobacco  chewers,  worn, 
abraded,  and  eroded  teeth  with  extensive  secondary  calcified  deposits, 
teeth  whose  pulp  canals  are  obstructed  by  pulp  nodules,  teeth 
with  metallic  oxids  in  tubuli,  teeth  with  leaky  old  fillings,  mainly  from 
the  same  cause,  namely,  clogged  tubuli.  In  most  cases  no  amount 
of  persistent  pressure  will  prove  successful.  According  to  Hertwig 
the  protoplasm  of  the  cell  primarily  transfers  irritation,  and  secon- 
darily, transmits  absorbed  materials,  and  therefore  the  anesthetic 
solution  has  to  pass  through  the  entire  length  of  the  dentinal  fiber 
before  the  nerve  tissue  of  the  pulp  is  reached.  Consequently  a  certain 
period  of  time  is  required  before  the  physiologic  effect  of  the  anes- 
thetic is  manifested,  and  this  period  of  latency  is  dependent  upon  the 
thickness  of  the  intermediate  layer  of  dentin.  The  successful  anes- 
thetization of  the  pulp  depends  largely  upon  this  most  important 
factor  of  allowing  sufficient  time  for  the  proper  migration  of  the  drug. 

Other  soluble  local  anesthetics,  such  as  nervocidin,  erythrophlein 
hydrochlorid,  quinin  and  urea  hydrochlorid,  etc.,  have  been  advised 
at  various  times  as  reliable  pulp  anesthetics.  Owing  to  numerous 
drawbacks,  these  drugs  have  never  obtained  popularity.  Refrigerant 
local  anesthetics  have  also  been  advised  for  the  extirpation  of  the  pulp. 
The  application  of  this  group  of  anesthetics  for  such  purposes  is  usually 
accompanied  by  many  disadvantages  which  materially  limit  its  useful- 
ness. 

Local  Anesthesia  for  Operations  about  the  Mouth,  Exclusive  of  the 
Extraction  of  Teeth. — In  operating  about  the  mouth  for  a  cyst,  a  tumor, 
etc.,  the  rhomboid  infiltration  of  the  affected  tissue  according  to 
Hackenbruch  affords  the  simplest  means  of  producing  a  most  satis- 
factory anesthesia. 

The  needle  is  inserted  at  (a),  and  at  once  slow  pressure  is  exerted 
on  the  piston,  moving  the  needle  steadily  along  the  external  line  of 


PERIDENTAL  ANESTHESIA  525 

the  tumor.  The  needle  is  now  partially  withdrawal,  without,  however, 
leaving  the  original  puncture,  and  a  second  injection  or  as  many  as 
may  be  needed  are  made  in  opposite  directions.  This  maneuver  is 
now  repeated  at  (6),  and  thus  a  circumscribed  infiltration  of  the  whole 
tumor  is  obtained.  If  the  tumor,  etc.,  be  very  large,  additional  punc- 
tures and  injections  may  be  made  as  outlined  in  the  schematic  drawing. 
After  waiting  ten  to  fifteen  minutes,  the  extirpation  of  the  tumor 
may  be  begun. 

The  anesthetization  of  the  soft  and  hard  palate  is  accomplished 
comparatively  easily.  The  injection  on  the  hard  palate  is  started  at 
the  gingival  edge  of  the  alveolar  periosteum  on  both  sides  of  the  jaw 
toward  the  median  line.  As  the  gum  tissue  is  extremely  dense,  great 
force  is  required  for  a  complete  infiltration  in  this  region,  and  only 
small  quantities  of  the  solution  are  required.  The  soft  palate  is  easily 
infiltrated  by  inserting  the  needle  posteriorly  to  the  third  molar. 


Fig.  419 


Small  tumors  and  cysts  on  the  tongue  or  the  floor  of  the  mouth  are 
best  anesthetized  by  the  rhomboid  infiltration  of  Hackenbruch.  For 
the  complete  extirpation  of  a  ranula,  the  injection  is  made  into  the  cyst 
wall  near  its  periphery,  after  which  the  cyst  is  slit  open  and  a  small 
quantity  of  the  anesthetic  solution  is  injected  into  its  inner  surface. 
Large  cysts,  tumors,  and  major  operations  on  the  tongue  requu-e  the 
anesthetization  of  both  lingual  nerves.  In  injecting  and  operating 
on  the  floor  of  the  mouth,  the  index  finger  of  the  left  hand  should  be 
placed  on  its  external  surface  as  a  guide  to  the  needle  or  the  knife. 

Local  anesthesia  is  indicated  in  most  minor  and,  relatively,  in  many 
major  operations  on  the  mucous  surfaces,  the  skin,  and  the  teeth. 
Local  anesthesia  is  not  a  substitute  for  general  anesthesia;  its  useful- 
ness is  materially  increased  by  familiarizing  one's  self  with  the  methods 
of  its  production  and  with  a  perfect  mastery  of  its  technic.  The  danger 
of  poisoning  has  been  eliminated  by  using  an  isotonic  solution  contain- 


526  LOCAL  ANESTHESIA 

ing  a  relatively  small  percentage  of  the  anesthetic  in  combination  with 
epinephrin.  Even  if  the  danger  of  general  narcosis  is  small  under  the 
very  best  conditions,  the  danger  of  local  anesthesia  is  always  less. 
The  great  majority  of  all  dental  operations  can  be  safely  carried  out 
under  local  anesthesia,  provided  the  operator  has  acquired  a  complete 
working  knowledge  of  the  various  components,  which,  as  a  whole,  con- 
stitute this  important  branch  of  dental  therapeutics. 


CHAPTER  XIII. 

PYORRHEA  ALVEOLARIS. 

By  RUSSELL  W.  BUNTING,  D.D.Sc. 

The  term  pyorrhea  alveolaris,  meaning  a  flow  of  pus  from  the 
alveolus,  has  been  given  a  very  broad  application.  Strictly  speaking, 
it  should  be  applied  only  to  the  pyogenic  forms  of  peridental  infection 
by  which  the  tissues  about  the  teeth  are  broken  down  with  a  resultant 
formation  of  pus.  But  by  common  usage  the  term  pyorrhea  has 
been  loosely  applied  to  all  peridental  diseases  which  are  related  to  the 
gingivae,  including  infective,  non-infective,  purulent  and  non-purulent 
types.  As  a  large  number,  if  not  the  majority,  of  peridental  infections 
are  non-purulent  in  character,  it  follows  that  the  term  pyorrhea  is 
very  often  a  misnomer  for  the  conditions  to  which  it  is  applied.  An 
effort  therefore  has  been  made  to  find  a  more  suitable  name  by  which 
the  various  peridental  affections  might  be  designated.  Among  other 
terms  which  have  been  suggested,  periodontoclasia  {peri  about,  odon 
tooth,  klasis  a  breaking,  literally  a  breaking  about  the  tooth)  has 
received  the  widest  acceptance.  This  term  for  the  sake  of  brevity 
and  euphony  may  be  shortened  to  dental  periclasia  of  which  several 
types  may  be  differentiated,  as  suppurative,  non-suppurative,  gingival, 
alveolar,  etc.  Although  these  terms  are  in  many  respects  commendable 
and  are  the  most  comprehensive  so  far  suggested,  their  usage  at  the 
present  time  is  very  limited.  In  view  of  this  fact,  for  the  sake  of  clarity 
we  will  use  in  this  discussion  the  following  two  terms:  gingivitis,  which 
will  include  all  disturbances  of  the  gingivae  in  which  little  or  no  loss 
of  attachment  of  the  soft  tissues  to  the  teeth  has  been  effected,  and 
pyorrhea  alveolaris,  which  will  be  applied  to  those  forms  of  peridental 
disease  in  which  the  attachment  of  the  hard  and  soft  tissues  has  been 
destroyed  an  appreciable  distance  down  the  side  of  the  root.  It  will 
be  necessary,  therefore,  to  use  the  anomalous  term  non-purulent  pyor- 
rhea, but  in  doing  so  it  must  be  remembered  that  pyorrhea  refers,  in  a 
generic  sense,  to  a  general  class  of  peridental  diseases. 

The  history^  of  the  development  of  our  knowledge  of  pyorrhea,  like 
that  of  dental  caries,  is  an  interesting  one.  Examinations  of  the  skulls 
of  prehistoric  man  show  that  even  these  peoples  were  afflicted  with 

1  The  early  history  of  pyorrhea  is  largely  taken  from  the  account  by  E.  C.  Kirk  in 
the  American  System  of  Operative  Dentistry,   1914. 

(527) 


528  PYORRHEA  ALVEOLARIS 

peridental  diseases,  and  early  writings  make  frequent  mention  of  mouth 
affections  which  caused  the  teeth  to  loosen  and  fall  out.  The  earliest 
recorded  treatise  dealing  with  the  disease  is  that  of  Pierre  Fauchard 
in  1728  who  described  its  most  prominent  clinical  features.  Following 
the  work  of  Fauchard,  sporadic  writings  appeared  from  various  sources 
in  which  meager  descriptions  of  the  symptoms  and  course  of  pyorrhea 
were  related.  In  1867  E.  Magitot  made  an  important  contribution 
to  the  subject  in  which  he  described  the  disease  as  a  progressive 
inflammation  which  destroyed  the  periosteal  membrane  and  cementum. 
He  thought  that  these  conditions  originated  deep  in  the  tissues  and 
were  not  necessarily  preceded  by  gingival  irritation  or  inflammation. 
He  attributed  their  cause  to  constitutional  changes  and  associated 
them  with  gout,  diabetes,  albuminuria,  and  rheumatism. 

In  1880  Serran  took  exception  to  the  views  of  Magitot,  and  stated 
as  his  opinion  that  all  peridental  diseases  began  in  an  inflammation 
of  the  gingival  tissues  due  to  the  presence  of  infection  or  calculi  about 
the  teeth.  He  believed  them  to  be  manifestations  of  purely  local 
conditions  and  not  necessarily  dependent  upon  general  or  systemic 
states.  Because  of  the  widely  diverging  views  of  these  writers  and 
the  discussions  which  grew  out  of  them,  the  Societe  de  Chirurgie  of 
Paris  appointed  a  commission  of  scientists  to  investigate  the  matter 
to  determine  which  of  the  two  theories  was  the  more  tenable.  In  the 
report^  which  they  gave  at  the  conclusion  of  their  study  of  the  problem 
the  commission  corroborated  the  views  of  Magitot.  They  stated  that 
peridental  diseases  did  not  begin  as  gingival  affections  but  rather  that 
the  primary  lesion  occurred  deep  in  the  pericementum  and  that  the 
gingivae  were  affected  only  secondarily.  They  held  that  the  disease 
was  not  due  therefore  to  local  causes,  but  was  rather  a  manifestation 
of  constitutional  disturbance. 

In  this  country  the  first  important  contribution  to  the  subject  was 
made  by  John  W.  Riggs  of  Hartford,  Conn.,  in  1875.^  He  emphatically 
denied  that  peridental  disease  arose  from  constitutional  causes.  On 
the  contrary,  he  claimed  that  it  began  as  a  local  inflammation  of  the 
gingival  tissues  which  in  turn  was  caused  by  the  irritation  of  calculi 
and  other  accretions  upon  the  teeth  contiguous  to  or  beneath  the  free 
margin  of  the  gums.  His  views  were  based  largely  upon  his  practical 
observations  that  if  in  the  treatment  of  pyorrhetic  affections  the 
accretions  be  completely  removed  from  the  teeth,  the  disease  is  usually 
arrested  and  permanently  controlled.  These  views  concerning  the 
etiology  of  peridental  diseases  and  the  clinical  demonstrations  which  he 
made  setting  forth  the  manner  of  their  treatment  aroused  so  much 

1  Bulletin  et  Memoirs  de  la  Soc.  de  Chir.,  Tome  vi,  p.  411. 

2  Pennsylvania  Journal  of  Dental  Science,  vol.  iii,  p.  99. 


PYORRHEA  ALVEOLARIS  529 

interest  that  for  many  years  this  condition  was  known  as  "Rigg's 
disease." 

During  the  years  that  have  followed,  students  of  these  affections  have 
been  divided  into  two  classes:  one,  the  localists  who  believe  that  the 
disease  is  purely  a  local  disturbance  arising  from  causes  that  are 
proximate  in  origin,  while  the  other  group  might  be  called  the  consti- 
tutionalists who  believe  that  pyorrhea  occurs  entirely  independent  of 
local  conditions  and  that  it  is  in  reality  an  expression  of  constitutional 
disturbance  or  disease.  Among  the  more  important  writings  on  the 
subject  are  those  of  G.  V.  Black^  who  treats  pyorrhea  alveolaris  as  a 
purely  local  disease.  He  considers  it  to  be  largely  an  inflammation 
and  destruction  of  the  peridental  membrane  by  a  process  which  is 
specific  in  character.  He  describes  the  initial  lesion  as  an  invasion  of 
the  peridental  membrane  by  certain  infectious  organisms  which  pene- 
trate deeply  into  the  tissues  along  the  so-called  pericemental  glands  of 
Black.  The  infections  which  have  thus  gained  entrance  to  the  deeper 
tissues  set  up  inflammations  and  degenerative  changes  which  spread 
to  the  adjacent  alveolar  process  and  cause  their  destruction. 

A  somewhat  different  view  was  expressed  by  A.  Witzel  of  Germany^ 
who  stated  that  peridental  disease  begins  as  an  inflammation  and  caries 
of  the  alveolar  border.  As  a  result  of  the  bone  destruction  a  deposit 
of  calculus  is  formed  upon  the  teeth  just  beneath  the  free  margin 
of  the  gum,  which  in  turn  constitutes  a  source  of  irritation  to  the 
gingival  tissues  producing  gingivitis  and  disturbances  in  the  surround- 
ing tissues.  Witzel  claims  that  this  process  is  wholly  local  and  inde- 
pendent of  constitutional  states,  but  that  it  originates  in  the  deeper 
bony  structures  about  the  teeth  rather  than  at  the  gum  margins. 

As  a  result  of  his  close  microscopic  study  of  peridental  tissues  in 
disease,  Zamnesky^  has  given  a  very  clear  description  of  the  process 
by  which  they  are  destroyed.  He  believes  that  pyorrhea  begins  as  an 
inflammation  of  the  gum  margin  destroying  first  the  epithelial  lining  of 
the  gingival  crevice  and  gradually  involving  the  deeper  soft  and  hard 
tissues  to  produce  necrotic  changes  in  them.  Therefore  he  considers 
the  process  to  be  a  local  necrotic  disintegration  of  the  alveolar  process 
which  begins  with  gingival  inflammation. 

Eugene  S.  Talbot  who  since  1896  has  written  voluminously  on  the 
subject,^  takes  a  middle  ground  in  the  discussion.     He  recognizes  the 

1  American  System  of  Dentistry,  vol.  v,  p.  953;  Operative  Dentistry,  G.  V.  Black, 
1908,  and  Special  Dental  Pathology,  G.  V.  Black,  1915. 
-  British  Journal  of  Dental  Science,  vol.  xxv,  p.  153. 

3  Journal  of  British  Dental  Association,  vol.  xxiii,  p.  585. 

4  Talbot:  Dental  Cosmos,  1896,  pp.  310,  660;  ibid.,  1905,  p.  310;  1909,  p.  1147;  1915, 
p.  485.  Talbot:  Dental  Summary,  1903,  pp.  435,  538;  ibid.,  1917,  p.  282.  Talbot: 
Dental  Items  of  Interest,  1906,  p.  837.  Talbot,  E.  S.:  Interstitial  Gingivitis,  1899  and 
1913. 

3i 


530  PYORRHEA  ALVEOLARIS 

importance  of  certain  local  causative  factors  such  as  infection,  calculi, 
etc.,  but  he  believes  that  the  most  significant  factor  in  the  process 
is  a  preliminary  degeneration  of  the  alveolar  process.  He  points  out 
that  because  of  evolutionary  development  of  man  a  marked  degenera- 
tion of  the  alveolar  process  has  occurred  with  the  result  that  in  the 
present  generation  these  bones  are  lightly  built  and  are  prone  to 
degenerative  changes  under  any  stress  or  nutritional  disturbance. 
He  states  that  the  initial  lesion  therefore  consists  in  preliminary 
degeneration  of  the  alveolar  bone  due  to  senility,  constitutional  fault, 
poisons,  etc.  If,  then,  local  irritative  factors  be  present,  they  acting 
in  conjunction  with  the  underlying  degenerative  changes,  may  produce 
the  characteristic  lesions  of  the  disease.  If,  on  the  contrary,  oral 
hygiene  has  been  maintained  and  no  local  irritations  are  present  the 
degeneration  of  the  bone  results  in  an  atrophic  shrinkage  of  the  soft 
and  hard  tissues  about  the  teeth  rather  than  in  true  pyorrhea. 

More  recently,  however,  the  great  majority  of  writers  and  con- 
tributors have  leaned  toward  the  localist's  point  of  view,  giving  special 
emphasis  to  the  part  played  by  the  infectious  organisms  involved. 
Inasmuch  as  bacteria  and  other  mouth  organisms  are  present  in  every 
case  of  pyorrhea,  it  has  always  been  a  matter  of  speculation  as  to 
whether  these  organisms  were  primarily  responsible  for  the  disease  or 
only  secondary  inhabitants  of  the  lesions.  Exhaustive  studies  of  the 
bacteriology  of  pyorrhea  have  been  made  by  various  investigators  each 
of  whom  has  searched  for  some  ever-present  predominating  organism 
which  might  prove  to  be  the  specific  cause  of  the  disease. 

W.  D.  Miller^  isolated  from  pyorrheal  pockets  the  Staphylococcus 
aureus  and  albus  and  Streptococcus  pyogenes,  and  described  about 
sixteen  other  types  of  organisms  which  he  did  not  isolate.  He  stated 
that  pyorrhea  is  essentially  an  infective  process  in  which  the  peridental 
tissues  are  destroyed  by  bacteria.  These  organisms  he  found  thriving 
in  the  lesions  in  a  mixed  culture,  several  different  forms  usually  being 
present  in  symbiotic  relationship  to  each  other.  As  he  could  determine 
no  constant  type  or  group  of  organisms  which  was  uniformly  present 
in  every  case.  Miller  concluded  that  pyorrhea  may  be  produced  by  a 
wide  group  of  organisms  in  varying  combinations  and  is  not  caused 
by  any  specific  type  of  bacteria. 

Vaccine  Therapy.^ — Kenneth  Goadby^  also  studied  the  bacterial 
flora  of  pyorrhea  and  found  that  S.  pyogenes,  M.  catarrhalis  and  S. 
albus  and  aureus  are  the  most  frequent  organisms  met  with  in  this 
disease.  He  claimed  he  had  succeeded  in  curing  cases  of  pyorrhea  by 
the  use  of  autogenous  vaccines  made  from  the  organisms  present  in 

1  Microorganisms  of  the  Human  Mouth,  1890,  p.  329. 

2  British  Medical  Journal,  1905,  vol.  ii,  p.  562. 


VACCINE   THERAPY  531 

the  lesions.  In  his  attempt  to  control  pyorrhea  by  vaccines  he  was 
pioneer  in  the  practice  of  vaccine  therapy  for  that  disease,  a  method 
which  later  came  into  considerable  prominence  and  which  for  a  time 
was  very  widely  adopted. 

Notable  in  this  connection  is  the  work  of  L.  S.  Medalia  who,  begin- 
ning with  1913^  wrote  several  extensive  articles  on  the  bacteriology  of 
pyorrhea  and  the  treatment  of  the  disease  by  vaccine  therapy.  He 
quotes  Zamnesky^  in  slipport  of  his  opinion  that  pyorrhea  is  essentially 
an  affection  of  the  bones  and  therefore  should  be  known  as  chronic 
alveolar  osteo-myelitis.  He  believes  that  these  tissue  degenerations 
are  produced  by  local  infections  which  are  variable  in  character,  no  one 
organism  being  the  specific  cause.  For  the  control  of  these  infections 
he  recommends  the  use  of  autogenous  vaccines  for  the  purpose  of 
raising  the  opsonic  index  of  the  body  against  the  particular  strains  of 
bacteria  which  happen  to  be  present  in  the  lesions.  By  vaccine  therapy 
in  conjunction  with  oral  prophylactic  measures  Medalia  claims  to  have 
had  a  high  percentage  of  cures. 

As  a  result  of  the  statements  made  by  Medalia  and  others  regarding 
the  benefits  which  were  to  be  derived  from  the  use  of  vaccines  in  the 
treatment  of  pyorrhea,  many  dental  investigators  and  practitioners 
made  practical  application  of  the  measures  suggested,  the  reports  of 
which  show  a  varying  degree  of  success.  Very  soon  those  who  were 
most  conversant  with  the  disease  and  who  had  the  widest  experience 
in  its  treatment  lost  faith  in  vaccine  therapy  and  discontinued  its  use. 
They  arrived  at  the  conclusion  that^  the  promiscuous  use  of  vaccines 
is  dangerous,  that  vaccines  when  used  for  pyorrhea  are  not  specific 
in  their  action,  and  that  the  disease  might  be  successfully  controlled 
by  the  more  simple  measures  of  surgical  interference,  without  which 
the  vaccine  would  be  of  no  avail. 

One  of  the  most  serious  objections  to  the  use  of  vaccines  for  the 
treatment  of  pyorrhea  is  the  fact  that  they  are  misleading  in  their 
symptomatology.  It  is  true  that  following  the  injection  of  autogenous 
and  even  stock  vaccines  a  marked  improvement  of  the  case  is  fre- 
quently seen.  The  pus  flow  may  cease  and  the  peridental  inflammation 
may  rapidly  decrease;  so  that  from  superficial  observation  it  might 
appear  that  the  case  were  permanently  cured.  But  unless  by  careful 
instrumentation  all  accretions  have  been  removed  from  the  denuded 
roots  and  the  root-surfaces  carefully  planed  no  permanent  reattach- 
ment of  the  soft  tissues  to  the  root  can  take  place.  Many  operators, 
therefore,  who  depend  upon  vaccine  therapy  in  the  treatment  of 

1  Dental  Cosmos,  1913,  p.  24. 

^  Journal  British  Dental  Association,  vol.  xxiii,  p.  585. 

3  Merritt:  Dental  Cosmos,  1916,  p.  62. 


532  PYORRHEA  ALVEOLARIS 

pyorrhea,  being  deceived  by  the  chnical  improvement  of  the  case,  fail 
to  perform  the  necessary  operative  procedures  with  the  result  that  the 
pockets  still  remain  about  the  teeth  to  be  reinfected  at  a  subsequent 
time.  Vaccines  then  are  but  temporary  in  their  action  and  may  be 
considered  only  in  the  light  of  questionable  adjuncts  to  surgical  pro- 
cedures. Today  vaccine  therapy  in  the  treatment  of  pyorrhea  has 
largely  fallen  into  disrepute  and  is  only  used  in  a  limited  way  by  a  few 
of  its  most  ardent  supporters.  '■ 

The  Ameba  Theory. — Perhaps  no  subject  ever  caused  such  widespread 
interest  in  the  dental  world  in  so  short  a  time  as  did  the  announce- 
ment of  Endameba  buccalis  as  the  specific  cause  of  pyorrhea  alveo- 
laris  by  the  simultaneous  reports  of  three  independent  groups  of  men. 
In  July,  1914,  Angelo  Chivaro'^  in  a  paper  given  before  the  American 
Dental  Society  of  Europe  in  Paris,  states  that  the  Endameba  buccalis 
is  usually  present  in  the  "materia  alba"  of  unclean  mouths  and  is 
always  found  in  pus  from  pyorrheal  pockets.  He  advances  the 
opinion  that  "the  endameba  has  not  a  pathogenic  action;  on  the 
contrary,  as  it  feeds  on  bacteria,  it  is  most  probably  an  aid  to  auto-- 
disinfection  of  the  mouth."  It  is  evident,  therefore,  that  he  considered 
the  endameba  in  the  light  of  a  mouth  scavenger  and  not  as  a  cause  of 
pyorrhea. 

During  the  same  month  M.  T.  Barrett^  before  the  Pennsylvania 
State  Dental  Society  in  Philadelphia  gave  a  preliminary  report  of  the 
studies  which  he  and  A.  J.  Smith  had  made  of  the  endameba  in  pyor- 
rhea. In  this  and  subsequent  writings,  Barrett  and  Smith  place  great 
stress  on  the  supposed  pathogenic  action  of  oral  amebse,  characterizing 
them  as  the  specific  cau,se  of  pyorrhea,  although  they  admit  that 
bacteria  may  have  a  part  in  the  destructive  process.  Being  confident 
of  the  validity  of  their  claims  they  began  the  administration  of  emetin, 
a  specific  drug  for  ameba,  which  they  gave  in  the  form  of  subcutaneous 
injection,  mouth  washes,  and  by  stomachic  dosage.  In  the  use  of  this 
amebacidic  treatment,  Barrett  and  Smith  and  their  collaborators 
claim  to  have  had  many  remarkable  cures  of  pyorrhea. 

In  September,  1914,  Bass  and  Johns  of  New  Orleans  read  a  paper^ 
on  the  amebic  theory  of  pyorrhea  in  which  they  hastened  to  publish 
the  results  of  their  investigations,  which  according  to  their  own  state- 
ment, had  not  been  pursued  more  than  one  month.  As  the  result  of 
this  brief  consideration  they  announced  as  their  opinion  that  amebse 
are  the  specific  cause  of  pyorrhea,  that  they  are  not  to  be  found  on 

1  Dental  Review,  1914,  p.  1122. 

2  Dental  Cosmos,  August,  1914,  p.  948. 

'  Dental  Summary,  December,  1914,  p.  994,  and  Jour.  Amer.  Med.  Assn.,  February 
13,  1915,  p.  553. 


SUCCINAMIDE  OF  MERCURY  533 

open  surfaces  or  in  healthy  mouths,  and  that  the  use  of  amebacides 
will  cure  pyorrhea.  They  later  published  a  book  entitled  "Alveolo- 
dental  Pyorrhea"  in  which  they  considered  the  various  types  of  the 
disease  as  being  produced  by  endameba  buccalis. 

From  the  extravagance  of  the  claims  made  by  the  American  expon- 
ents of  this  theory,  a  widespread  interest  was  aroused  and  as  a  conse- 
quence, a  wholesale  use  of  emetin  in  the  treatment  of  pyorrhea  followed. 
At  the  same  time  careful  studies  of  the  theory  were  made  by  dental 
scientists  and  practitioners  who  sought  to  know  the  truth  about  the 
matter.  Notable  among  these  are  the  investigations  of  Price  and 
Bensing^  who  describe  the  various  types  of  amebse  which  inhabit  the 
mouth.  They  found,  as  did  Chivaro,  that  the  amebse  ingested  bacteria, 
from  which  fact  they  inferred  that  these  protozoa  were  beneficial  to 
the  tissues  rather  than  harmful  to  them.  HartzelP  made  practical 
and  clinical  studies  of  the  effect  of  emetin  on  cases  of  pyorrhea,  the 
results  of  which  convinced  him  that  such  medication  was  of  doubtful 
value,  and  that  proper  surgical  and  prophylactic  means  would  effect 
a  cure  without  the  aid  of  emetin.  The  views  of  Hartzell  were 
corroborated  by  practically  all  practitioners  who  treated  pyorrhea 
intensively.  The  great  mass  of  evidence  and  opinion  which  was 
given  out  by  those  who  studied  the  subject  was  largely  contradictory 
to  the  theory  while  very  little  corroboratory  evidence  could  be  found. 
Cases  in  which  emetin  was  used  seemed  to  show  a  temporary  improve- 
ment, but,  as  in  the  use  of  vaccines,  the  operator  almost  invariably 
relied  so  much  upon  the  beneficial  effects  of  the  drug  that  he  failed  to 
perform  properly  the  necessary  operative  and  prophylactic  measures. 
As  a  result,  healing  of  the  pockets  was  not  attained  and  a  relapse 
occurred  within  a  very  short  time.  Consequently  the  interest  which 
was  aroused  by  the  amebic  theory  of  pyorrhea  and  the  use  of  emetin 
in  its  treatment  w^as  short  lived,  dying  out  almost  as  rapidly  as  it  arose, 
and  the  treatment  of  pyorrhea  by  means  of  emetin  is  no  longer  practiced 
except  by  a  very  few  enthusiasts. 

Succinamide  of  Mercury. — ^During  the  year  1915  and  later,  the  dental 
corps  of  the  Navy  reported  the  successful  treatment  of  pyorrhea  by 
deep  muscular  injections  of  succinamide  of  mercury.  G.  H.  Reed,* 
Wright,^  and  White,^  acting  upon  the  supposition  that  mercury  pro- 
duces antibodies  in  the  blood  and  thereby  retards  the  action  of  parasites, 
made  use  of  that  drug  in  the  form  of  a  succinamide  to  control  the 
gro\\i;h  of  the  microorganisms  in  pyorrhea.     From  its  use  they  claimed 

1  Journal  National  Dental  Association,  1915,  p.  143. 

2  Emetin  vs.  Surgery,  Hartzell,  Journal  Allied  Dental  Society,  1916,  p.  7. 
'  Items  of  Interest,  April,  1915,  p.  241. 

*  Dental  Cosmos,  1915,  p.  1003,  and  the  Journal  Allied  Dental  Society,  1916, p.  305. 
6  Dental  Cosmos,  1915,  p.  405. 


534  PYORRHEA  ALVEOLARIS 

they  had  obtained  pronounced  beneficial  results  in  which  the  pus  ceased 
to  flow  from  the  pockets  within  twenty-four  hours  after  the  injection, 
the  inflammation  of  the  tissues  subsided  and  a  disappearance  of  the 
pyorrheal  lesions  ensued.  It  was  suggested  by  them  that  this  method 
be  used  in  conjunction  with  careful  operative  procedures,  but  beneficial 
results  were  noted  even  when  no  instrumentation  was  performed.  It  is 
the  opinion  of  Wright  that  the  mercury  has  a  two-fold  parasitrophic 
action:  first,  the  mercury  unites  directly  with  the  organisms,  that  is, 
it  forms  a  chemical  combination  with  the  bacterial  proteins;  and, 
second;  the  mercury  stimulates  in  the  tissues  the  formation  of  a  specific 
antibody  against  the  organisms  of  pyorrhea.  In  the  treatments  which 
they  gave  four  or  five  doses  of  succinamide  of  mercury  were  admin- 
istered one  week  apart,  beginning  with  f  grain  and  reducing  i  each  week. 
The  injections  were  made  deep  in  the  gluteal  muscles  alternating  each 
week  between  the  two  sides  of  the  buttocks.  Only  scanty  reference 
has  been  made  to  this  treatment  in  the  literature,  from  which  we  infer 
that  the  method  has  not  received  any  wide  acceptance  or  adoption. 
There  are  good  reasons  to  believe  that  in  certain  types  of  cases  the 
administration  of  the  drug  in  conjunction  with  careful  operative  and 
prophylactic  procedures  may  be  of  benefit  in  controlling  the  infection. 
This  is  especially  true  when  the  organism  present  is  of  a  virulent  and 
persistent  type  which  the  surrounding  tissues  are  not  able  to  success- 
fully combat.  This  form  of  treatment  is,  however,  open  to  the  same 
criticism  as  are  vaccines  and  emetin  in  that  when  used  to  combat 
pyorrhea  it  affords  a  sense  of  false  security  by  which  many  operators 
will  be  led  to  neglect  or  incompletely  perform  the  necessary  surgical 
procedures  without  which  no  drug  or  medicament  can  effect  a  cure  of 
the  disease. 

More  Recent  Views  of  the  Cause  of  Pyorrhea  Alveolaris. — In  addition 
to  the  amebic  theory  several  hj'potheses  have  been  advanced  as  to 
the  specificity  of  one  or  another  type  of  mouth  organism  to  produce 
pyorrhea.  Of  these  the  opinions  of  Noguchi,  Kritchevsky  and  Seguin, 
and  Hartzell  are  the  most  notable.  Each  of  these  investigators  looks 
upon  pyorrhea  as  a  local  infective  process  in  which  the  peridental  tissues 
are  destroyed  by  a  specific  type  of  organism  which  they  believe  is 
responsible  for  the  disease. 

H.  Noguchi,^  of  the  Rockefeller  Institute  of  Medical  Research, 
isolated  from  pyorrheal  pockets  and  grew  in  pure  culture  a  new  species 
of  spirocheta  which  he  has  called  the  Treponema  mucosum.  This 
organism  which  is  smaller  than  the  Vincentini  spirillum  has  regular 
convolutions  similar  to  the  organism  of  syphilis.    They  do  not  grow 

1  Treponema  Mucosum,  Journal  of  Experimental  Medicine,  1912,  xvi,  103. 


VIEWS  OF  THE  CAUSE  OF  PYORRHEA  ALVEOLA  HIS       535 

on  healthy  tissues  but  thrive  only  on  such  as  have  been  injured  or 
impaired  in  their  nutrition.  They  are  purulent  in  type  and  occasionally 
stimulate  a  mucinous  secretion.  Noguchi  recognizes  the  presence  of 
streptococcus,,  staphylococcus  and  pneumococcus  groups,  of  organisms 
in  peridental  disease,  but  he  believes  that  the  Spirocheta  mucosum, 
together  with  the  Spirocheta  microdentinum,  and  the  Vincentini 
spirillum,  with  the  fusiform  bacillus,  constitute  a  class  of  organisms 
which  are  directly  responsible  for  the  disease. 

In  1918,  Kritchevsky  and  Seguin^  of  the  Pasteur  Institute  reviewed 
the  work  of  Noguchi  on  Spirochetee  and  that  of  Wright,  Kolle,  and 
others  who  claimed  to  have  successfully  treated  pyorrhea  by  arsenical 
and  mercurial  preparations  which  have  a  specific  action  against 
spirochete.  The  authors  then  reported  a  large  series  of  pyorrhetic 
cases  which  they  had  treated  by  intravenous  injection  and  by  local 
application  of  salvarsan  and  neosalvarsan.  They  claimed  that  in  this 
manner  they  had  obtained  very  beneficial  results  consisting  of  a  rapid 
disappearance  of  the  spirochete  from  the  pyorrheal  pockets,  and  a 
remarkable  improvement  in  the  clinical  appearance  of  the  cases.  They 
stated,  however,  that  this  treatment  alone  gives  but  a  temporary  relief 
and  that  for  a  permanent  cure  it  is  necessary  that  a  most  careful  scaling 
and  polishing  of  the  roots  be  performed  and  a  thorough  and  unrelenting 
course  of  oral  hygiene  be  established. 

In  a  discussion  of  the  cause  of  pyorrhea,  Hartzell  in  August,  19 18,^ 
stated  emphatically  as  his  belief  that  it  was  the  streptococcal  group  of 
organisms  which  produced  the  initial  lesion  of  the  disease.  As  a  result 
of  the  extensive  investigation  which  he  has  made  of  this  type  of  infec- 
tion during  the  past  five  years,  he  believes  that  streptococci  are  neces- 
sary to  true  pyorrhea,  and  that  they  are  the  first  to  penetrate  the  tissue 
and  create  the  initial  lesion,  thus  preparing  the  way  for  the  staphy- 
lococci and  other  purulent  types  of  organisms  which  in  turn  dissolve 
the  peridental  tissues  and  create  the  pocket.  He  emphatically  states 
that  the  streptococcal,  staphylococcal,  and  pneumococcal  group  are 
the  only  organisms  of  any  importance  in  pyorrhea,  and  of  these  the 
streptococci  are  the  specific  instigators  of  the  process.  For  the  control 
of  these  infections  and  the  cure  of  the  disease  he  depends  solely  upon 
the  thorough  application  of  surgical  and  hygienic  measures. 

It  will  be  noted  that  practically  all  American  students  of  pyorrhea 
consider  it  to  be  a  local  disease  arising  largely  from  local  irritations  and 
infections,  with  the  exception  of  Talbot,  who  takes  a  middle  ground, 
believing  that  both  local  and  constitutional  causes  are  involved.    The 

1  La  Presse  Medicale,  Paris,  May  13,  1918,  and  the  Dental  Cosmos,  September,  1918, 
p.  781. 

2  Items  of  Interest,  January,  1919,  p.  45. 


536  PYORRHEA  ALVEOLAR! S 

majority  of  European  students,  however,  have  taken  the  opposite  view 
of  the  question  and  regard  pyorrhea  as  an  expression  of  systemic  disease. 
Their  opinions  were  very  clearly  summed  up  by  Maurice  Roys^  of 
Paris  in  a  paper  which  he  gave  in  London  at  the  Sixth  International 
Dental  Congress  in  1914.  He  reviewed  the  writings  of  Magitot, 
Galippe  Julien  Tellier,  Mendell  Joseph,  Hopewell-Smith,  Talbot  and 
others,  all  of  whom  placed  considerable  stress  on  the  early  degenerative 
changes  in  the  alveolar  bone  in  cases  of  true  pyorrhea,  Roys  then 
attempts  to  rule  out  all  other  causes  of  pyorrhea  by  a  process  of 
exclusion  and  formulates  a  theory  in  which  he  places  the  greatest 
emphasis  on  an  initial  degeneration  of  the  bone  due  to  what  he  terms, 
"precocious  senility."  He  believes  that  local  trauma  and  infection 
enter  into  the  process  of  peridental  destruction  but  considers  them  to 
be  adjuvant  causes  and  secondary  to  degenerations  in  the  alveolar 
bone  which  are  general  and  systemic  in  their  origin.  He  asserts  that 
local  irritation,  such  as  mechanical  stress,  infection  and  faulty  oral 
hygiene,  when  acting  alone,  produce  gingivitis  but  not  pyorrhea  unless 
a  precocious  senile  degeneration  of  the  alveolar  border  has  taken  place. ■ 
In  this  manner  he  explains  those  cases  in  which  the  oral  hygiene  is 
poor  and  the  gingivae  are  inflamed  but  no  pyorrhea  is  present.  On  the 
other  hand,  he  believes  that  senile  degenerations  of  the  alveolar  bone 
without  local  irritations  produce  only  an  atrophy  of  the  peridental 
tissues,  and  if  a  rigid  oral  hygiene  he  maintained  no  pyorrheal  pockets 
will  be  formed.  This  contribution  of  Roys  is  an  excellent  exposition  of 
the  constitutionalist's  conception  of  pyorrhea  and  should  be  carefully 
studied  by  all  those  who  are  interested  in  the  subject. 

In  all  of  the  foregoing  the  reader  will  have  seen  that  there  are  many 
phases  of  the  problem  of  pyorrhea  alveolaris  which  at  the  present  time 
are  not  fully  understood.  The  variance  of  opinions  which  have  been 
expressed  has  caused  considerable  confusion  in  the  minds  of  many  as 
to  the  nature  of  the  process  and  the  basic  principles  which  are  involved, 
so  that  it  stands  today  as  the  least  widely  understood  and  most  neglected 
of  all  dental  diseases.  Having  reviewed  the  various  theories  and  opin- 
ions which  have  been  suggested  as  to  the  cause  and  course  of  pyorrhea 
alveolaris,  we  will  now  consider  the  known  facts  regarding  the  process 
and  point  out  definitely  established  principles  relative  to  the  practical 
control  of  the  disease,  irrespective  of  the  theories  and  speculations  which 
have  been  advanced  thereto. 

The  Significance  of  Local  Operative  Procedures.— During  all  of  the 
years  in  which  the  controversy  regarding  the  cause  and  nature  of 
pyorrhea  has  been  carried  on,  a  certain  group  of  operators  has  been 

1  Dental  Cosmos,  August,  1918,  p.  659. 


GENERAL  PRINCIPLES  OF  PYORRHEA  537 

successfully  treating  and  controlling  pyorrhea  by  local  operative  pro- 
cedures. New  theories  came  and  went  but  these  pyorrhea  workers 
continued  in  the  even  tenor  of  their  ways  to  cleanse  surgically  the 
affected  root-surfaces,  to  remove  all  irritants,  and  to  establish  per- 
manent mouth  cleanliness,  as  a  result  of  which  an  arrest  of  the  destruc- 
tive process  and  a  subsequent  healing  of  the  lesions  was  secured  in  a 
large  percentage  of  cases.  So  beneficial  have  been  the  results  obtained 
by  those  operators  who  have  become  proficient  in  this  form  of  treat- 
ment that  there  is  no  longer  any  room  for  doubt  as  to  the  efficacy  of 
these  measures  to  control  many  forms  of  pyorrhea.  If  constitutional 
factors  are  involved  in  their  cases,  these  operators  have  considered 
them  only  in  a  general  way,  bending  their  greatest  efforts  toward  the 
perfection  of  a  careful  technic  of  root-surgery  and  the  establishment  of 
thorough  mouth  cleanliness.  In  a  great  majority  of  cases  in  which  the 
destructive  process  has  not  advanced  too  far  an  arrest  of  the  disease 
is  effected  and  a  healing  of  the  lesion  is  brought  about  while  in  beginning 
cases,  practically  without  exception,  the  pyorrheal  tendency  is  checked 
and  the  progress  of  the  disease  permanently  prevented  by  local  pro- 
phylactic measures  and  by  the  establishment  of  oral  hygiene.  By 
reason  of  the  success  which  was  obtained  by  these  local  procedures, 
many  have  been  led  to  believe  that  pyorrhea  is  wholly  a  local  disease 
and  is  entirely  independent  of  systemic  conditions.  Even  those  who 
believe  in  the  constitutional  origin  of  pyorrhea  admit  that  local 
measures,  if  thoroughly  performed,  are  largely  effective  in  checking  the 
disease,  and  indeed  there  are  few  who  have  made  a  close  study  of  the 
problem  and  have  impartially  adjudged  the  results  of  these  operators 
who  do  not  agree  as  to  the  efficacy  of  this  method  of  treatment.  The 
question  then  arises  as  to  how  the  conception  of  pyorrhea  as  an  expres- 
sion of  systemic  or  constitutional  disease  may  be  reconciled  with  the 
fact  that  it  is  amenable  to  local  treatment.  For  a  better  understanding 
of  this  phase  of  the  subject  it  will  be  necessary  to  consider  more  in 
detail  the  causes  and  course  of  pyorrhea  alveolaris. 

General  Principles  of  Pyorrhea. — Pyorrhea  alveolaris  is  a  disease  of 
the  oral  cavity  which  is  confined  to  the  tissues  immediately  surround- 
ing the  teeth  and  is  characterized  by  infections,  inflammatory  changes 
and  a  progressive  destruction  of  the  attachment  of  the  supporting 
tissues  about  the  teeth.  These  degenerations  consist  in  a  disintegra- 
tion of  the  pericemental  membrane  and  a  scission  of  its  fibers  beginning 
at  the  gingival  crevice  and  proceeding  apically  along  the  root  of  the 
tooth.  Concurrently,  degenerative  changes  take  place  in  the  contigu- 
ous bony  structures  of  the  alveolar  process  by  which  they  undergo 
molecular  disintegration  or  metaplasia  to  fibrous  tissue.  As  a  result 
of  these  two  degenerative  processes  a  characteristic  lesion  or  pocket  is 


538  PYORRHEA  ALVEOLARIS 

formed  along  the  lateral  surface  of  the  root  and  is  progressively 
deepened  as  the  disease  advances.  When  the  supporting  structures 
have  been  sufficiently  destroyed  the  tooth  becomes  loose  and  eventually 
is  lost. 

This  destructive  process  is  not  constant  or  uniform  but  varies  quite 
widely  in  its  course  and  the  pathologic  picture  which  it  presents.  In 
some  instances  severe  inflammation  is  set  up  with  the  production  of  an 
active  flow  of  pus  while  in  others  the  inflammatory  reactions  are  slight 
and  no  pus  is  evident.  Certain  cases  are  associated  with  calculus 
formation  both  external  and  subgingival,  while  others  are  devoid  of 
calcareous  deposits.  Pyorrhea,  therefore,  is  not  a  definite  or  specific 
disease  but  rather  is  a  variable  complex  of  symptoms  expressive  of  a 
combination  of  local  and  general  factors  which  enter  into  the  process. 
Of  these  a  wide  variety  of  local  irritative  and  infective  factors  may  be 
recognized  which  exercise  an  evident  causal  relationship  to  the  disease. 
These  local  disturbances  are  augmented  by  many  general  constitutional 
states  which  predispose  the  tissues  toward  pyorrheal  affections.  The 
course  of  each  case  is  determined  by  the  particular  type  of  local  or 
general  factor  which  is  most  prominent  as  a  causative  agent  and  the 
quality  of  the  local  tissue  reactions.  It  is,  therefore,  possible  to  recog- 
nize certain  definite  forms  of  pyorrhea  and  to  catalogue  the  various 
types  according  to  the  specific  causative  agents  which  are  present  and 
the  type  of  tissue  reactions  to  them.  For  a  clear  understanding  of 
this  complex  disease,  concerning  which  there  is  so  much  uncertainty 
and  confusion,  it  is  necessary  that  we  learn  to  analyze  each  case  by  rea- 
soning from  cause  to  effect,  that  we  search  for  all  possible  causes  both 
local  and  systemic,  and  that  we  study  and  evaluate  the  type  of  bodily 
resistance  as  it  is  expressed  in  local  tissue  reactions.  In  this  manner 
the  course  and  clinical  pictures  of  a  large  majority  of  these  cases  may 
be  made  clear  to  us  so  that  we  may  truly  appreciate  the  nature  of  the 
pathologic  process  which  has  taken  place  and  determine  the  manner  in 
which  it  may  be  checked. 

In  the  study  of  pyorrhea  alveolaris  it  is  necessary  that  we  consider 
the  structure  and  peculiar  qualities  of  the  tissues  which  are  involved 
by  the  disease.  The  tissues  are  those  which  immediately  surround 
the  teeth,  namely,  the  alveolar  bone,  the  peridental  membrane  and  the 
overlying  gum  tissues  (see  Fig.  88) .  The  alveolar  process  which  affords 
support  to  the  teeth  and  the  soft  tissues  consists  of  cancellous  bone, 
except  on  the  periphery  and  the  walls  of  the  alveoli,  where  it  is  con- 
densed and  cribriform  in  type.  Normally  this  alveolar  bone  surrounds 
the  roots  of  the  teeth  nearly  to  the  gingival  line  and  in  the  interproxi- 
mate  region  it  projects  crownward  in  a  tapering  wedge  to  support  the 


GENERAL  PRINCIPLES  OF  PYORRHEA  539 

interproxiuiate  gingivcv.  The  peridental  membrane  lines  the  walls  of 
each  alveolus  and  by  its  dense  white  fibrous  tissue  gives  firm  attach- 
ment betw^een  the  tooth  and  the  surrounding  bone.  The  peridental 
fibers  also  extend  upward  into  the  free  margin  of  the  gum  on  all  sides 
of  the  tooth  and  by  the  pull  which  they  exert  upon  these  tissues  they 
serve  to  draw  them  tightly  about  the  neck  of  each  tooth.  The  peri- 
dental membrane  possesses  a  rich  and  free  blood  supply  which  is  derived 
from  vessels  which  enter  the  tissue  from  three  sources,  namely,  at  the 
apex  from  vessels  w^hich  enter  the  pulp,  on  the  lateral  surfaces  of  the 
root  from  vessels  w^hich  enter  the  membrane  through  the  walls  of 
the  alveoli,  and  in  the  cervical  region  from  the  periosteal  circulation. 
The  vessels  of  the  peridental  circulation  are  arranged  for  the  most  part 
parallel  with  the  long  axis  of  the  tooth  and  are  accompanied  by  a 
system  of  Ij'mphatics^  which  take  the  same  general  direction.  Overly- 
ing the  bony  structure  there  is  first  a  periosteal  covering  upon  w^hich 
is  superimposed  a  dense  connective  tissue  submucosa  and  a  highly 
specialized  stratified  pavement  epithelium,  the  mucous  membrane. 
These  mucous  and  submucous  tissues  are  firmly  attached  to  the  bone 
by  fibers  of  the  periosteum  and  to  the  teeth  by  the  fibers  of  the  peri- 
dental membrane.  Unlike  the  deeper  structures  the  gingival  tissues 
are  supplied  by  bloodvessels  w^hich  have  no  collateral  communication, 
being  endarterial  in  tjT)e. 

Normally  these  tissues  are  highly  resistant  to  infection  and  to  traum- 
atic injm'ies  incident  to  the  mastication  of  hard  foods.  In  health, 
the  overlying  tissues  are  hard  and  firm  and  are  not  easily  ruptured  or 
torn  from  their  positions.  And  w^hen  they  have  been  injured  the  oral 
tissues  show^  a  remarkable  recuperative  power  by  which  healing  of  even 
severe  w^ounds  is  rapidly  accomplished  when  the  injiu-y  is  not  of  long 
diu-ation.  But,  on  the  other  hand,  injuries  which  are  continued  for  a 
considerable  space  of  time  even  though  they  be  of  low  potential  and 
seemingly  insignificant  may  induce  profound  degenerative  changes  in 
these  tissues  and  a  lowering  of  normal  resistive  power.  These  low  grade 
chronic  irritations  set  up  circulatory  changes  in  the  gingival  tissues, 
namely,  active  and  passive  h5T3eremia  which,  because  of  the  fact  that 
these  tissues  possess  little  or  no  collateral  circulation  usually  terminate 
in  passive  congestion  and  stasis.  The  vessels  become  engorged  with 
stagnant  or  slowly  moving  blood,  the  tissues  swell  and  are  infiltrated 
with  inflammatory  exudates  producing  a  marked  distm-bance  of  the 
overlying  tissues  w^hich  condition  we  designate  as  gmgivitis.  These 
circulatory  disturbances  vary  according  to  the  severity  of  the  irritant 

1  Noyes  and  Dewey:  The  Lymphatics  of  the  Dental  Region,  Jour.  Am.  Med.  Assn., 
1918,  p.  179. 


540  PYORRHEA  ALVEOLARIS 

and  the  t^^e  of  tissue  reaction  to  them.  In  one  individual  a  given 
local  irritant  will  give  rise  to  a  profound  inflammatory  reaction  and 
hypertrophy  of  the  gingival  tissues,  while  in  another,  in  response  to  the 
same  irritant  the  peridental  tissues  will  degenerate  rapidly  because  of 
the  fact  that  the  local  protective  reactions  are  weak. 

If  the  tissue  reactions  are  sufficiently  active,  severe  inflammations 
of  the  gingivae  may  continue  for  some  time  without  any  serious  affection 
of  the  deeper  tissues  or  disturbance  of  their  attachment  to  the  roots  of 
the  teeth.  Gingival  inflammation  may  exist,  therefore,  for  years  under 
these  conditions  without  the  production  of  true  pyorrhea.  But  when 
the  resistive  powers  of  the  tissues  are  not  of  good  order  or  when  a 
particularly  virulent  type  of  organism  becomes  implanted  in  a  gingival 
crevice,  especially  when  the  gingival  circulation  has  been  disturbed 
by  local  irritation  or  by  systemic  fault,  degenerations  of  the  deeper 
tissues  take  place.  The  first  step  in  this  process  consists  in  a  meta- 
plasia of  the  bony  alveolar  border  about  the  tooth  and  a  dissolution  of 
the  peridental  fibers.  The  bony  trabeculse  undergo  halesteresis  osseum 
by  which  they  are  decalcified  and  changed  to  fibrous  tissue.  At  the 
same  time  the  peridental  fibers  are  progressively  severed  and  a  sub- 
gingival space  or  pocket  is  formed  which  is  open  to  the  gingival  crevice, 
being  bounded  on  one  side  by  the  root  of  the  tooth  and  on  the  other  by 
the  inflamed  and  degenerating  gingival,  subgingival  and  alveolar  tissues. 

In  this  pyorrheal  pocket  various  infectious  and  pathogenic  organisms 
live  and  thrive,  exerting  their  characteristic  action  upon  the  surround- 
ing tissues,  against  which  the  tissues  in  tiu-n  seek  to  protect  themselves. 
As  in  the  case  of  periapical  infection  the  type  of  protective  reaction 
depends  upon  the  type  of  organism  which  predominates  in  the  lesion. 
When  the  infection  is  an  actively  purulent  type,  the  reactions  against 
the  1  are  acute  and  highly  inflammatory.  By  a  profuse  diapedesis  of 
leukocytes  and  lymphocytes  a  wall  is  built  about  the  lesion  which  later 
becomes  organized  into  a  permanent  granulation  tissue  similar  to  that 
of  an  abscess.  It  then  virtually  becomes,  first  an  acute  and  later,  a 
chronic  abscess  which  may  persist  in  statu  quo  for  months  or  years. 
After  the  manner  of  an  abscess,  the  organisms  continually  break  down 
tissue,  blood,  and  lymph  cells  with  the  production  of  pus,  while  the 
granulations  about,  either  partially  or  completely  replace  the  lost 
tissues  by  bringing  in  new  blood  and  lymph  cells  and  fibroblasts. 
When  the  condition  becomes  chronic  there  is  a  tendency  on  the  part  of 
the  surrounding  tissues  to  wall  off  the  infectious  process  by  the  forma- 
tion of  a  fibrous  tissue  capsule  as  in  chronic  abscesses.  This  is  the 
purulent  type  of  pyorrhea  alveolaris. 

But  when  the  predominating  organism  is  non-purulent  in  character 
like   the   streptococcus-pneumococcus   group,   a   somewhat  different 


GENERAL  PRINCIPLES  OF  PYORRHEA 


541 


picture  is  presented.  Against  these  organisms  the  tissue  reactions  are 
of  low  order  and  less  protective  than  the  former  tj'pe.  As  a  rule,  the 
overlying  gingival  tissues  are  not  highly  inflamed  or  h^pertrophied, 
and  frequently  show  little  pathologic  change  other  than  a  slight 
retraction.  Consequently,  these  may  easily  be  overlooked,  especially 
in  their  early  stages.     The  deeper  tissues  undergo  a  mild  form  of 


Fig.  420. — Pyorrhea,  hypertrophic  type;  swelling  of  gum  tissues ;  strong  tissue  reactions. 

degeneration  and  are  replaced  by  a  fibrous  tissue  of  new  order.  Deep 
peridental  lesions  are  formed  in  which  there  is  little  or  no  pus,  and  in 
the  adjacent  tissues  many  lymphocytes  and  plasma  cells  are  massed 
in  an  unorganized  state.  This  form  of  pyorrhea  corresponds  in  tj-pe, 
therefore,   to   the  periapical   granulomata,   in   which   the   infectious 


Fig.  421. — Pyorrhea,  passive  type;  deep  pockets  about  practically-  all  tcetli  but  no  outward 
signs  present.     No  swelling;  gums  nearly  normal  in  color;  no  inflammatory  reaction. 


organisms  tend  to  penetrate  the  tissues  and  produce  in  them  prolifera- 
tive degenerations.  It  is  undoubtedly  in  these  non-purulent  types  of 
peridental  infection  that  the  danger  of  metastatic  focal  infection  is  the 
greatest. 

The  characteristic  action  of  the  different  t^pes  of  infection  and  the 
varying  local  and  general  reactions  to  them  are  reflected  in  the  clinical 


542  PYORRHEA  ALVEOLARIS 

appearances  of  pyorrhea  which  are  presented.  In  case  the  reactions 
are  of  a  good  order,  the  tissue  changes  are  clearly  evident,  often  livid 
in  appearance^  and  are  readily  recognized  (Fig.  420).  While  in  other 
cases,  either  because  of  the  presence  of  a  streptococcal  organism  of  low 
virulence  or  a  low  state  of  general  bodily  activity  the  tissue  reactions 
are  mild,  the  clinical  disturbances  are  slight  and  little  evidence  of  the 
process  is  given  other  than  a  hidden  and  obscure  pyorrheal  pocket 
(Fig.  421) .  It  follows  that  cases  of  pyorrhea  in  which  the  most  dangerous 
types  of  infection  are  involved  and  the  most  severe  tissue  destruction 
is  accomplished  often  escape  clinical  observation  and  no  effort  is  made 
to  check  them.  In  every  clinical  examination,  careful  search  should 
be  made  for  the  characteristic  pyorrheal  pocket  and  only  when  it  is 
determined  that  the  gingivae  are  firmly  attached  about  each  tooth  and 
that  no  sub-gingival  pockets  have  been  formed  may  it  safely  be  said 
that  pyorrhea  does  not  exist. 

Causes  of  Pyorrhea  Alveolaris. — In  a  consideration  of  the  causes  of 
pyorrhea,  it  is  very  essential  that  we  keep  clearly  in  mind  that  the  seat 
of  the  primary  lesion  is  unquestionably  located  in  the  investing  tissues  • 
about  the  teeth,  which,  in  the  course  of  the  disease,  are  progressively 
destroyed  or  changed  in  their  character.  Irrespective  of  all  the  con- 
flicting theories  which  have  been  held  thereto,  it  must  be  admitted  that 
as  long  as  the  normal  attachment  of  the  gingival  tissue  remains  intact 
about  the  teeth,  there  can  be  no  characteristic  lesion  of  pyorrhea.  It  is 
only  by  the  breaking  of  this  close  union  of  gingival  tissue  to  the  neck 
of  the  tooth,  that  a  pyorrheal  pocket  may  be  effected.  If,  therefore, 
these  gingival  tissues  could  be  kept  in  health  and  normal  relationship 
to  the  teeth  which  they  surround,  true  pyorrhea  would  not  occur. 

Inasmuch  as  the  perfection  of  the  attachment  of  the  gingival  tissues 
to  the  tooth  and  their  resistance  to  infectious  organisms  depends 
upon  the  healthy  tone  or  pull  of  the  peridental  fibers  which  support 
them,  it  follows  that,  whenever  disturbances  occur  in  the  gingival 
circulation,  either  from  local  or  constitutional  causes,  the  tissues  suffer 
from  malnutrition,  the  tone  of  the  fibers  is  lowered  and  the  gingival 
tissues  fall  away  from  the  neck  of  the  tooth.  Thus,  by  reason  of  local 
circulatory  disturbances,  the  gingival  crevice  becomes  widened  and 
patent,  affording  an  easy  access  by  which  the  oral  microorganisms 
may  invade  and  attack  the  deeper  tissues.  Following  the  initial 
invasion,  the  future  coiuse  of  the  infectious  process  depends  upon 
the  type  of  local  tissue  reactions  which  oppose  it.  In  one  case 
active  hyperemia  will  be  set  up  which  may  effectually  protect  the 
deeper  tissues  from  invasion,  and  confine  the  infection  to  the  super- 
ficial tissues,  while  in  another  case  when  the  tissue  reactions  are 
not  of  good  order  a  similar  injury  may  give  rise  to  a  rapid  degeneration 


CAUSES  OF  PYORRHEA  ALVEOLAR! S  543 

and  deep  infection  of  the  underlying  peridental  tissues.  Because  of 
the  complex  nature  of  this  process  it  is  often  difficult  to  determine 
whether  the  various  types  of  local  disturbances  to  the  peridental 
circulation  act  as  primary  and  exciting  causes  of  the  disease  or  merely 
predispose  to  it  by  preparing  the  way  for  some  other  factor.  But 
clinical  observation  has  definitely  determined  that  when  in  the  treat- 
ment of  these  disturbances  all  local  irritants  have  been  completely 
removed  and  the  normal  peridental  circulation  has  been  reestablished, 
the  course  of  the  disease  is  checked,  and  in  the  majority  of  cases  is 
permanently  arrested.  In  the  treatment  of  these  conditions  by  local 
operative  measures  the  relationship  between  cause  and  effect,  namely, 
the  local  irritants  and  the  peridental  disturbance,  is  so  evident  that  we 
are  led  to  view  the  local  disturbances  of  circulation  as  highly  important 
factors  in  the  inception  of  pyorrhea.  The  causes  of  these  disturbances 
may  be  enumerated  as  follows : 

Local  Causes —  Trauma  of  Foods. — The  oral  tissues  are  constantly 
subjected  to  various  forms  of  traumatic  injury.  A  certain  amount  of 
friction  and  buffeting  of  the  teeth  and  surrounding  tissues  by  the 
mastication  of  hard  foods  seems  to  be  beneficial  to  them,  as  it  assists 
in  cleaning  the  mouth  and  stimulates  the  peridental  circulation.  But 
when  excessive  and  repeated  pressures  are  brought  to  bear  upon  the 
hard  or  soft  tissues  of  the  mouth,  irritation  and  circulatory  disturbances 
are  set  up  which  result  either  in  a  hypertrophy  or  a  degeneration  of  the 
tissues  depending  upon  the  type  of  their  reaction  to  the  injury.  Trau- 
mata frequently  occur  in  interproximate  spaces,  when  the  normal 
contact  has  been  lost  and  food  is  crowded  upon  the  interproximate  gum 
septa  during  mastication.  An  example  of  the  hypertrophic  type  may 
be  seen  in  Fig.  422  in  which  the  interproximate  gum  is  swollen  as  a 
result  of  the  crowding  of  food  between  the  teeth.  In  Fig.  423  a  similar 
case  is  sho-v^ai  in  which  the  gum  tissue  has  been  destroyed  and  deep 
pyorrheal  pockets  have  been  formed  along  the  roots  of  the  adjacent 
teeth. 

A  single  pyorrheal  pocket  may  be  established  on  the  labial,  buccal, 
or  lingual  surface  of  a  tooth  as  the  result  of  injury  by  the  excessive 
excursions  of  food  against  it  when  the  corresponding  enamel  surface 
is  flat  or  lacks  normal  contour.  As  has  been  pointed  out  (see  p.  165) 
these  flat  tooth  surfaces  usually  result  in  a  simple  retraction  of  the 
gum  contour  at  that  point,  but  it  not  infrequently  occurs  that  a 
specific  rupture  is  made  in  the  tissues  and  by  subsequent  infection  a 
deep  pyorrheal  lesion  is  effected  (Fig.  424) . 

Operative  Traumata. — In  the  performance  of  various  operative  pro- 
cedures the  gum  tissues  are  frequently  injured.  As  a  rule,  wounds 
of  the  mucous  membrane  heal  readily,  but  when  the  resistance  is  low 


544  PYORRHEA  ALVEOLARIS 

infectious  organisms  may  become  implanted  on  the  site  of  such  injuries 
to  form  a  deeper  lesion.  For  example,  cutting  of  the  gingival  tissues 
by  saws,  files,  ligatures,  bands,  etc.,  may  be  followed  by  an  infection 
of  the  wound  leading  to  the  establishment  of  a  pyorrheal  lesion.  Gold 
shell  crowns  which  are  poorly  fitted  to  the  roots  and  extend  down  deep 


Fig.  422. — -Interproximate  trauma  of  Fig.  423. — Interproximate  trauma  of 

food  between  molar  and  bicuspid,  pro-  food  between  molars,  producing  shrink- 

ducing  hypertrophy  of  gum  tissues. ^  age  of  tissue  and  loss  of  gum  septum. i 

into  the  pericementum,  overhanging  proximate  fillings  and  ill-fitting 
clasps  on  dentures  are  common  offenders  of  this  type.  These  injuries 
set  up  circulatory  disturbances  in  the  surrounding  tissues  by  the  irrita- 
tions which  they  produce  and  if  the  protective  reactions  are  not  of  high 
order,  infection  and  tissue  destruction  will  ensue. 


Fig.  424. — Retraction  of  gingivse  on  labial  surface  of  upper  and  lower  left  centrals 
resulting  from  traumata  of  food  excursions  over  teeth  having  no  labial  contour.  Upper 
right  central  is  a  porcelain  crown  having  a  prominent  labial  contour  which  has  effectually 
protected  the  gum  tissues  about  it. 

Traumatic  Occlusion. — Pyorrheal  lesions  may  be  established  about 
one  or  more  teeth  as  the  result  of  excessive  or  abnormal  occlusion. 
Not  every  case  of  mal-occlusion  will  produce  such  lesions,  but  in  cases 
in  which  the  general  health  and  metabolism  are  of  low  order,  the 
irritation  of  excessive  occlusion  frequently  acts  as  a  predisposing  cause 
of  peridental  infection.     In  the  treatment  of  all  cases  of  pyorrhea  it 

1  Whinney,  M.  A.:  Dental  Review,  1907,  p.  611. 


CAUSES  OF  PYORRHEA   ALVEOLARIS 


545 


has  been  found  necessary,  therefore,  to  correct,  as  far  as  is  possible,  all 
faults  of  occlusion  for  the  reason  that  they  act  as  a  contributory  cause 
of  irritation  which  must  be  corrected  before  healing  of  the  lesion  may  be 
effected  (see  p.  168). 

Trauma  of  Calculi. — It  is  a  matter  of  common  observation  that  the 
great  majority  of  cases  of  pyorrhea  are  associated  with  a  deposition  of 
calculi  on  the  teeth.  Considerable  speculation  has  been  made  as  to 
the  part  which  these  deposits  play  in  the  process.  It  is  not  clear 
whether  they  are  active  exciting  causes  of  the  peridental  disturbance 
or  are  secondary  depositions  laid  down  as  a  result  of  the  tissue  degenera- 
tion. Certain  it  is  that  they  do  act  as  important  factors  in  the  process 
whenever  they  are  present.  If  they  impinge  upon  the  soft  tissue, 
either  externally  or  beneath  the  gum  margin, 
they  will  produce  injury  to  them  as  the  teeth 
move  in  mastication.  By  the  rough  surface 
which  they  present  they  interfere  with  the 
cleansing  of  the  mouth  and  tend  to  harbor 
food  and  infectious  materials  about  the  teeth. 
They  are  actively  irritant  in  the  peridental 
tissues  and  constitute  a  contributory  factor 
to  peridental  disease. 

Several  different  varieties  of  calculi  may 
be  distinguished,  which  have  been  divided 
by  the  majority  of  writers  into  two  classes, 
salivary  and  serumal  or  sanguinary.  It  is 
not  clear  where  the  dividing  line  between 
these  two  varieties  of  calculi  may  be  placed 
since  all  pyorrheal  pockets  are  more  or  less 
open  to  the  saliva  and  there  is  always  a  pos- 
sibility that  even  deposits  which  are  formed 
deep  down  on  the  lateral  surface  of  the  roots 

may  be  salivary  in  origin.  This  we  have  shown  experimentally  to  be 
possible^  by  producing  outside  of  the  mouth  deep  calculi  on  teeth  which 
were  covered  with  modeling  compound  to  simulate  the  gums  leaving 
narrow  crevices  along  the  lateral  surfaces  of  the  roots  to  form  deep 
pockets.  When  immersed  for  several  weeks  in  a  solution  of  calcium 
salts,  the  concretions  shown  in  Fig.  425  were  produced. 

Calculi  vary  in  color,  form,  hardness,  brittleness  and  the  rapidity 
with  which  they  are  built.  Accumulations  on  the  surface  of  the  teeth 
occur  most  frequently  on  the  buccal  surfaces  of  upper  molars  and 
bicuspids  opposite  the  opening  of  Stenson's  duct  and  on  the  lingual 


Fig.  425.  —  Subgingival 
calculus  formed  artificially 
on  root  imbedded  in  model- 
ing compound  with  a  pocket- 
like crevice  about.  Labial 
portion  of  modeling  com- 
pound broken  away  to  show 
calculi. 


1  Bunting  and  Rickert:  Journal  National  Dental  Association,  August,  1915,  p.  256. 
35 


546  PYORRHEA  ALVEOLARIS 

surfaces  of  the  lower  incisors.  These  deposits  are  self-evident  and 
easily  recognized  but  those  which  are  formed  beneath  the  gum  are  not 
so  easily  discovered.  The  subgingival  types  consist  of  small  granules, 
plates  or  scale-like  rings  (Fig.  90)  which  may  encircle  the  necks  of  the 
teeth  or  extend  along  the  lateral  surface  of  the  root  in  a  deep  pyorrheal 
pocket.  They  are  frequently  hidden  from  view  and  offer  considerable 
difficulty  in  removal  (Fig.  426) . 


Fig.  426. ^Pyorrhea  with  heavy  subgingival  calculus  about  roots  of  all  teeth. 

Nature  and  Origin  of  Calculi. — ^The  salivary  calculi  on  analysis  are 
found  to  be  composed  of  masses  of  calcium  phosphate  and  carbonate 
built  upon  a  mucinous  or  colloidal  matrix  and  arranged  in  concentric 
layers  about  a  central  nidus.  The  findings  of  Rainey  and  Ord^  relative 
to  the  origin  of  biliary  and  urinary  calculi  have  shed  considerable  light 
on  the  method  by  which  salivary  calculi  are  formed.  They  found  that 
in  a  medium  containing  colloid,  earthy  salts  were  precipitated  in 
spheroidal  masses  which  in  time  coalesced  to  form  large  concretions. 
They  proved  that  urinary  and  biliary  calculi  are  formed  by  the  precipi- 
tation of  urinary  and  biliary  salts  in  colloidal  materials  as  mucin, 
albumin,  etc.  In  the  same  manner  the  formation  of  salivary  calculi 
may  be  explained  as  a  precipitation  of  calcium  salts  from  the  saliva  in 
the  mucin  and  colloids  present  in  the  mouth.  It  has  been  observed^ 
that  the  first  step  in  the  formation  of  calculi  consisted  in  the  deposition 
upon  the  teeth  of  calco-globulin  in  the  form  of  a  flaky  white  precipitate. 
This  deposit  when  first  laid  down  is  soft  and  viscous,  insoluble  in  water 
but  may  be  removed  easily  by  the  brush  or  finger.  In  time  it  becomes 
hard  and  brittle  and  takes  on  the  general  characteristics  of  dental 
calculi.  A  copious  flow  of  this  calco-globulin  follows  the  ingestion  of  a 
full  meal  of  highly  nutritious  foods  and  is  also  more  abundant  during 

1  On  the  Influence  of  Colloids  upon  Crystalline  Forms  and  Cohesion,  London,  1879. 

2  Black,  G.  v.:  Dental  Review,  1912,  p.  337,  and  in  his  Special  Dental  Pathology. 
1915. 


CAUSES  OF  PYORRHEA  ALVEOLAR! S  547 

illness.  The  statement  has  also  been  made^  that  salivary  calculi  are 
formed  as  the  result  of  fermentation  processes  in  the  oral  cavity  giving 
rise  to  acids,  notably  lactic  acid.  The  acid  thus  formed  supposedly 
precipitates  the  mucin  from  the  saliva  which  in  turn  drags  down  the 
phosphates  and  carbonates  of  calcium  to  form  a  mass  upon  the  teeth 
which  in  time  hardens  to  form  calculi. 

It  is  evident  that  calculi  when  first  laid  down  are  soft  and  mucinous 
in  character,  in  which  form  they  may  be  removed  easily  by  the  tooth 
brush  and  other  mechanical  measures.  Later  they  become  hard  a  ad 
firmly  attached  to  the  surface  of  the  teeth  from  which  they  may  only 
be  dislodged  by  considerable  force.  The  rate  of  tartar  formation  in 
the  mouth  is  not  dependent  upon  the  amount  of  calcium  in  the  saliva, 
for  we  have  found  that  the  calcium  content  of  the  saliva  is  no  higher 
in  individuals  who  have  considerable  dental  calculus  than  in  those  who 
have  little.  The  process  seems  to  be  dependent  upon  the  amount  of 
mucinous  and  colloidal  matter  in  the  saliva  which  when  deposited  upon 
the  teeth  constitutes  a  matrix  in  which  inorganic  salts  from  the  saliva 
and  possibly  the  blood  are  precipitated.  The  control  of  calculus 
formation  therefore  may  be  accomplished  by  the  limitation  of  calco- 
globulin  in  the  salivary  secretion  by  regulation  of  the  diet  and  by  the 
removal  of  the  deposits  from  the  teeth  daily  while  they  are  soft,  at 
which  time  their  removal  may  be  accomplished  readily  by  the  tooth 
brush  and  dental  floss.  Furthermore,  it  is  a  common  observation  that 
when  a  mouth  is  put  under  a  strict  regime  of  oral  prophylaxis  by  which 
oral  fermentations  are  largely  decreased,  the  tendency  to  form  calculi 
is  greatly  diminished. 

Bacteria.- — ^As  we  have  related  in  the  section  on  History,  every 
pyorrhetic  lesion  is  infested  with  a  variety  of  microorganisms  of 
which  the  most  common  forms  are  streptococci,  staphylococci,  B. 
fusiformis,  spirochete,  and  types  of  amebse.  These  organisms  doubt- 
less play  an  active  part  in  tissue  destruction  and  in  the  formation  of  the 
characteristic  lesions  of  the  disease.  It  is  usual,  however,  that  upon 
close  study  of  the  case  some  other  predisposing  cause,  either  local  or 
general,  may  be  found  which  prepared  the  way  for  the  bacterial  invasion 
and  without  which  the  infection  would  not  have  occurred.  But  occa- 
sionally a  case  is  presented  in  which  no  predisposing  cause  is  apparent; 
no  calculi  or  other  traumata  are  present  and  no  constitutional  fault  is 
evident.  In  them  the  active  causative  factor  is  a  particularly  virulent 
type  of  organism  which  seemingly  has  the  ability  to  penetrate  the 
peridental  tissues  unaided  by  any  other  factor.  Beginning  cases  of 
this  type  may  be  seen  in  mouths  that  are  comparatively  clean  and 

1  Burchard,  H.  H.:  Dental  Cosmos,  1895,  p.  821,  and  1898,  p.  1.    Also  E.  C.  Kirk  and 
others. 


548 


PYORRHEA  ALVEOLARIS 


hygienic,  their  only  fault  being  a  narrow  plaque  of  bacterial  growth 
about  the  cervix  of  each  tooth  (Fig.  427).  As  a  result  of  this  growth  a 
marked  gingivitis  is  seen  about  all  the  teeth  (Fig.  428),  which  disappears 
after  careful  and  thorough  prophylactic  measiu-es  have  been  performed. 


Fig.  427.- 


-Location  of  bacterial  plaque  with  disclosing  solution.  Highly  infective  organ- 
isms present  producing  gingivitis. 


These  cases  are  relatively  rare  and  are  seemingly  due  to  the  presence 
of  a  highly  infective  type  of  organism,  although  it  is  possible  that  if  our 
clinical  vision  were  keen  enough  we  might  discover  some  predisposing 
and  determining  factor  which  inaugurates  the  process  other  than  the 
microorganisms. 


Fig.  428. — Severe  gingivitis,  infective  type,  no  calculus  being  present. 

Cigarette  Smoking. — ^We  have  observed  a  limited  number  of  cases 
of  pyorrhea  in  which  the  lesions  were  confined  to  the  labial  surface  of  the 
upper  anterior  teeth,  the  remainder  of  the  mouth  not  being  affected 
(Fig.  429).  In  each  of  these  cases  a  history  of  inveterate  cigarette 
smoking  was  obtained.  The  nature  and  location  of  the  lesions  coupled 
with  the  history  led  us  to  suspect  that  the  resistance  of  the  labial 
mucous  tissues  had  been  lowered  by  the  direct  action  of  the  smoke 
from  cigarettes  held  in  the  lips.  This  view  was  supported  by  the  fact 
that  when  the  cigarettes  were  held  in  a  mouth-piece  by  which  the  smoke 
was  directed  beyond  the  teeth  to  the  interior  of  the  mouth  and  prophy- 


CAUSES  OF  PYORRHEA  ALVEOLARIS 


549 


lactic  measures  were  instituted,  the  inflammation  subsided  and  the 
tissues  healed. 

Although  the  local  causes  of  pyorrhea  just  enumerated  in  many  cases 
seem  to  be  active  and  potential  factors  in  the  disease,  the  local  dis- 
turbances which  they  produce  are  profoundly  modified  by  the  general 
and  constitutional  status  of  the  body  as  a  whole.  As  has  been  pre- 
viously stated,  a  most  prominent  characteristic  of  peridental  disease 
is  the  inflammatory  reaction  by  which  the  tissues  oppose  the  invading 
process.  When  these  reactions  are  of  high  order,  local  irritations  excite 
strong  circulatory  reactions  which  are  hypertrophic  in  type  and  are 
strongly  resistive  to  invading  organisms.  In  this  manner  the  tissues 
successfully  withstand  continued  indignities  from  local  injury  without 
undergoing  degeneration  or  disintegration.  On  the  other  hand,  when 
the  local  reactive  powers  of  the  affected  tissues  are  low,  rapid  destruc- 
tion and  deep  pyorrheal  involvement  may  take  place  as  the  result  of  a 


Fig.  429. — Severe  pyorrhea  f)n  anterior  teeth,  associated  with  heavy  cigarette  smoking. 


mild  local  injury.  The  significance  of  the  local  causes,  and  their  ability 
to  produce  peridental  disease  is  directly  dependent  therefore  upon  the 
protective  powers  of  the  tissues  affected.  As  the  quality  of  protective 
reaction  which  the  local  tissues  possess  is,  in  turn,  largely  determined 
by  the  general  health  and  bodily  metabolism  of  the  individual,  the 
inception  and  progress  of  every  case  of  pyorrhea  is  uifluenced  and  often 
dominated  by  general  and  constitutional  states.  Abundant  illustra- 
tions of  this  fact  may  be  seen  in  the  differmg  t}3)es  of  cases  which  are 
presented,  on  the  one  hand,  in  individuals  who  are  weak,  debilitated, 
and  mal-nourished,  and  on  the  other,  in  those  who  are  strong,  robust 
and  full  blooded.  Those  who  are  constitutionally  weak  are  frequently 
predisposed  to  pyorrheal  infections  which  run  a  rapid  course  and 
produce  deep  involvement  and  destruction  of  tissues.  The  stronger 
type  of  individual  is  more  often  affected  by  gingivitis  of  a  h;yTpertrophic 
and  proliferative  order  and,  as  a  rule,  shows  a  marked  immunity  toward 


550  PYORRHEA  ALVEOLARIS 

pyorrhea!  invasion.  When  pyorrhea  does  occur  in  this  latter  class, 
some  other  metabolic  fault  may  often  be  found  by  reason  of  which 
the  natural  resistance  of  the  local  tissues  has  been  lowered.  These 
nutritional  disturbances  may  be  so  slight  that  they  escape  clinical 
observation  or  they  may  be  manifest  derangements  which  are  severe 
in  type.  It  has  been  observed  frequently  that  pyorrhea  may  be  asso- 
ciated with  various  systemic  diseases,  as  arthritis,  diabetes  mellitus, 
syphilis  tuberculosis  and  other  debilitating  affections.  These  systemic 
disturbances  undoubtedly  act  as  predisposing  causes  to  peridental 
disease  by  lowering  the  general  bodily  resistance  against  infection  and 
certain  of  them  have  a  more  direct  causative  relationship  by  virtue  of 
the  fact  that  during  the  course  of  the  disease  various  foreign  and 
irritative  substances  from  the  altered  salivary  secretions  are  laid  down 
in  or  upon  the  peridental  tissues. 

Systemic  Causes. — Gout  and  Arthritis. — Among  the  systemic  dis- 
eases which  are  associated  with  pyorrhea,  gout  and  arthritic  affections 
are  very  commonly  recognized.  In  the  course  of  these  diseases  the  body 
suffers  from  an  excessive  retention  of  uric  acid  in  the  blood  and  tissues 
as  a  result  of  which  serious  nutritional  and  metabolic  disturbances  are 
produced  in  all  bodily  tissues.  As  a  further  characteristic  of  these 
affections,  salts  of  uric  acid  may  be  deposited  in  certain  tissues  in  the 
form  of  crystals  of  sodium  biurate.  These  deposits  usually  occur  in 
the  articulatory  joints  producing  gout  and  arthritis  and  may  also  be 
laid  down  in  the  gingival  capillaries  and  in  the  peridental  membrane, 
where  they  act  as  irritants  and  mechanical  obstructors  of  the  circula- 
tion. In  cases  of  severe  arthritis,  the  resistance  of  the  peridental 
tissues  to  pyorrhetic  mfections  may  be  potentially  lowered  with  the 
result  that  individuals  so  affected  are  definitely  predisposed  to  peri- 
dental diseases. 

Diabetes  Mellitus. — It  has  been  noted  that  diabetic  patients  are 
prone  to  pyorrhea.  The  marked  debility  and  nutritional  disturbances 
attendant  upon  the  disease  are  sufficient  to  account  for  the  lowered 
resistance  of  the  oral  tissues.  Furthermore,  as  a  prominent  charac- 
teristic of  the  disease  there  is  a  tendency  of  all  tissues  toward  infection 
and  these  infections  when  once  begun  run  a  rapid  and  virulent  course. 
The  mouths  of  diabetics  are  usually  in  a  poor  state  of  oral  hygiene  and 
bacterial  growth  is  prolific.  About  all  the  teeth  there  is  found  a  pasty 
mucous  colloidal  material  which  interferes  with  oral  cleanliness  and 
in  which  the  microorganisms  thrive.  In  diabetes,  therefore,  the  oral 
fermentations  are  high,  the  resistance  of  the  tissues  is  lowered  and 
pyorrhea!  invasion  is  common. 

Systemic  Poisons. — ^Predisposition  to  pyorrhea  may  arise  from 
systemic   intoxication.    The   source   of   these   poisons   may   be   the 


CAUSES  OF  PYORRHEA  ALVEOLARIS  551 

introduction  of  drugs  through  stomachic  or  subcutaneous  routes, 
the  elaboration  of  toxins  from  bacterial  invasion,  and  the  production 
of  poisonous  substances  as  the  result  of  faulty  body  metabolism.  In 
the  first  group,  perhaps  the  most  spectacular  example  is  that  of  mercurial 
poisoning  which  has  long  been  associated  with  oral  disease  and  saliva- 
tion. After  a  continued  dosage  of  mercury  the  gum  tissues  take  on  a 
characteristic  bluish  color  which  is  diagnostic  of  mercurialization.  In 
the  circulation  of  this  drug  through  the  body  there  is  a  tendency  for  it 
to  become  lodged  in  the  gingival  capillaries  where  it  mechanically 
occludes  the  vessels  and  produces  passive  congestion  and  thrombosis. 
The  blue  color  of  the  gums  is  indicative  of  venous  congestion  in  the 
vessels  which  lie  immediately  beneath  the  mucous  membrane.  As  a 
result  of  profound  circulatory  and  nutritional  disturbances  the  resist- 
ance of  the  peridental  tissues  is  lowered  and  they  frequently  succumb 
to  pyorrhetic  invasion.  It  has  been  noted,  however,  that  if  in  cases 
of  mercurialization  the  mouth  be  kept  clean  and  in  a  hygienic  state, 
these  congestive  and  inflammatory  conditions  of  the  gingival  tissues 
do  not  occur.  In  explanation  of  this  phenomenon  it  is  claimed  that 
the  deposition  of  mercurial  salts  in  the  gingivge  is  dependent  upon  the 
presence  in  the  mouth  of  certain  products  of  fermentation  (probably 
sulphides),  arising  from  the  decomposition  of  foods.  When  the 
mercuric  compounds  in  the  gingival  circulation  come  into  contact  with 
these  sulphides  which  may  diffuse  through  the  mucous  membrane  an 
insoluble  compound  of  mercury  is  formed  which  is  lodged  in  the 
capillaries  of  the  peridental  tissues.  When  no  oral  fermentations 
exist  the  mercury  remains  in  solution  in  the  blood  stream  and  is  not 
deposited.  The  rationality  of  this  premise  is  well  supported  by  the 
fact  that  in  many  syphilitic  clinics  in  which  a  rigid  regime  of  oral 
prophylaxis  is  instituted  for  every  patient  large  qy.antities  of  mercury 
are  given  without  producing  any  serious  disturbance  in  the  peridental 
tissues.  In  many  instances  dentifrices  containing  potassium  chlorate 
are  used.  This  ingredient  supposedly  assists  in  maintaining  the 
mercury  in  the  soluble  chlorid  form. 

A  similar  relationship  is  noted  in  regard  to  lead  and  other  forms  of 
metal  poisoning.  In  each  case  they  disturb  the  gingival  circulation 
and  lower  the  resistance  of  these  tissues  against  infection.  As  a  rule 
it  may  be  said  that  their  deposition  is  largely  favored  by  faulty  oral 
hygiene. 

Auto-intoxication. — ^During  the  com-se  of  many  diseases  and  dis- 
tm-bances  of  metabolism  poisonous  substances  are  produced  by  the 
body  and  are  given  off  to  the  general  circulation.  These  may  consist 
of  waste  products  which  the  body  has  failed  to  eliminate  or  in  abnormal 
and  harmful  products  of  cell  metabolism.     Examples  of  this  class  have 


552  PYORRHEA  ALVEOLARIS 

already  been  cited  in  the  cases  of  arthritis  and  gout.  The  condition 
known  as  acidosis  also  should  be  included  in  this  class  of  poisons. 
Normally,  the  reaction  of  the  blood  is  alkaline  and  the  maintenance  of 
this  alkalinity  is  of  great  importance  to  body  metabolism.  When  by 
disturbances  of  function  an  excess  of  acids  is  present  in  the  blood  and 
tissues  all  enzyme  and  chemical  changes  in  the  body  are  disturbed. 
Severe  acidosis  occurs  in  diabetes,  cancer,  after  anesthetics  and  in 
certain  periods  of  pregnancy.  A  milder  form  arises  from  excessive  acid 
ingestion  or  from  incomplete  oxidation  of  foods  by  the  body.  These 
hyperacid  states  are  usually  obscure  and  not  easily  recognized  but 
there  are  strong  evidences  that  they  often  act  as  predisposing  factors 
in  peridental  disease  and  unless  corrected,  militate  against  the  successful 
treatment  of  the  case.  Under  the  direction  of  a  competent  internist 
acidosis  may  often  be  relieved  by  prescribing  a  balanced  diet  and  by 
the  administration  of  alkalies. 

Intestinal  Intoxication. — It  has  been  noted  by  many  writers  and 
practitioners  that  pyorrhea  is  frequently  associated  with  constipation. 
In  addition  to  the  ingested  food  and  drug  poisons  which  may  be 
absorbed  from  the  intestine  there  is  a  class  of  poisonous  products 
which  are  formed  in  the  intestine  by  the  bacterial  fermentation  of 
ingested  food.  This  latter  form  of  intoxication  is,  as  a  rule,  much  less 
acute  than  that  of  drugs  and  food  poisons.  They  constitute  a  mild 
subacute  or  chronic  intoxication  producing  changes  in  metabolism  which 
are  not  easily  traced  to  their  ultimate  source.  The  elaboration  of  these 
poisonous  products  and  their  absorption  from  the  intestine  are  favored 
by  chronic  constipation  and  obstruction  or  dilatation  of  the  bowel. 
The  most  significant  intestinal  poisons  are  the  various  split  products 
of  protein  decomposition,  indol,  skatol,  phenol,  ptomaines,  etc.,  which 
when  absorbed  into^the  system  act  either  as  active  poisons  or  as  dis- 
turbers of  cell  metabolism.  In  many  cases  when  the  individual  has 
followed  an  ill-balanced  diet  which  is  overloaded  with  proteins  and 
when  because  of  sedentary  occupation,  lack  of  exercise  or  digestive 
faults,  the  foods  undergo  putrefaction  in  the  intestinal  tract,  rather 
than  digestion,  the  products  of  this  decomposition  and  retained  fecal 
matter  may  enter  the  circulation  to  produce  systemic  poisoning.  The 
frequency  with  which  pyorrhea  is  associated  with  constipation,  exces- 
sive meat  ingestion  and  lack  of  exercise  strongly  suggests  that  intestinal 
intoxication  may  play  an  active  part  in  the  inception  and  continuation 
of  peridental  disease. 

Age. — Pyorrhea  seldom  occurs  in  the  young  and  vigorous  indivi- 
duals but  is  limited  almost  solely  to  those  of  middle  or  advanced  age. 
The  great  predominence  of  its  occurrence  in  the  later  years  of  life 
indicates  that  predisposition  to  peridental  disease  increases  with  age. 


CAUSES  OF  PYORRHEA  ALVEOLARIS  553 

This  tendency  may  arise  from  a  physiologic  decadence  of  the  peridental 
tissues,  from  a  general  lowering  of  metabolic  efficiency  and  resistance 
of  the  body  as  a  whole,  or  to  a  change  in  the  oral  secretions  as  a  result 
of  which  calculi  and  viscous  materials  are  laid  down  upon  the  tissues 
to  act  as  local  irritants  or  to  interfere  with  oral  hygiene. 

In  a  consideration  of  the  etiology  of  pyorrhea  it  must  be  admitted 
that  constitutional  factors  play  a  more  or  less  important  part  in  every 
case  of  the  disease;  in  certain  instances  it  is  only  a  subordinate  one  and 
in  others  it  constitutes  the  dominant  and  determining  factor.  As  we 
have  stated  previously,  many  operators  who  are  successful  in  the 
treatment  of  peridental  disease  have  failed  to  observe  the  relationship 
of  general  bodily  states  to  the  affections  which  they  treat  because  of 
the  fact  that  by  the  performance  of  local  operative  and  prophylactic 
measiu-es  alone  they  are  able  to  arrest  and  control  a  great  majority  of 
pyorrheal  cases.  Since  the  disease  frequently  yields  to  local  operative 
procedures,  they  conclude  that  it  is  essentially  a  local  disturbance  and 
independent  of  constitutional  causes.  In  the  explanation  of  this 
situation  and  in  answer  to  the  question  which  was  asked  in  the  section 
on  the  Significance  of  Local  Operative  Procedures,  as  to  the  manner 
in  which  pyorrhea,  a  systemic  disease,  might  be  controlled  by  local 
measures  alone,  the  following  statements  may  be  made: 

If,  as  has  been  pointed  out,  pyorrhea  is  essentially  a  destruction  of 
peridental  tissues  by  infectious  organisms  arising  from  a  lowering  of 
the  resistance  of  these  tissues,  it  follows  that  any  procedure  which 
will  decrease  the  causative  factors  and  increase  the  resistance  and 
combative  power  of  the  tissues  will  tend  to  arrest  the  progress  of  the 
disease  and  may  effect  a  cure.  It  is  to  this  end  that  practically  all 
operative  and  oral  prophylactic  measures  are  directed.  Upon  the 
removal  of  all  traumatic  and  mechanical  irritants,  the  disturbances 
which  they  have  produced  in  the  peridental  circulation  will  cease.  As 
a  rule,  in  these  cases  excessively  high  fermentative  processes  predomi- 
nate throughout  the  oral  cavity  and  the  bacterial  life  is  vastly  increased 
over  the  normal.  When  prophylactic  measures  are  completely  per- 
formed these  abnormal  bacterial  growths  are  reduced  to  the  point  at 
which  they  are  no  longer  significant  and  the  general  infective  pictiue  of 
the  oral  cavity  disappears.  A  similar  process  occurs  in  the  pyorrhetic 
lesion.  In  the  act  of  removing  the  sub-gingival  calculi  from  the  roots 
by  operative  measures  and  by  planing  their  surfaces  a  considerable 
amount  of  infective  material  is  mechanically  removed  from  the  tissues. 
In  this  manner  the  tissues  are  relieved  by  mechanical  irritation  and  the 
bacterial  flora  both  oral  and  sub-gingival  are  greatly  reduced.  Further- 
more, in  the  performance  of  these  operative  procedures  more  or  less 
bleeding  occurs  as  a  result  of  which  the  stagnant  and  congested  blood 
is  drained  from  the  tissues  and  an  active  circulation  is  stimulated. 


554  PYORRHEA  ALVEOLARIS 

The  immediate  effect  of  local  operative  measm'es  consists  in  the 
removal  of  mechanical  irritants,  a  marked  decrease  of  infectious 
organisms,  and  a  stimulation  of  the  peridental  circulation.  If  the 
infectious  organisms  be  sufficiently  decreased  to  the  point  where  the 
invaded  tissues  with  their  quickened  and  renewed  circulation  may 
successfully  combat  the  remaining  organisms  (complete  sterility  not 
being  practicable  in  oral  tissues)  the  peridental  disease  may  be  arrested 
and  healing  take  place  as  the  direct  result  of  local  procedures  alone. 
And  in  fact,  this  is  frequently  accomplished  even  in  cases  in  which 
general  and  constitutional  factors  have  been  largely  concerned  in  the 
process.  In  them  the  decrease  of  the  attacking  force  and  the  increase 
of  resistance  and  recuperative  power  of  the  local  tissues  are  able  to 
control  the  disease  notwithstanding  the  general  predisposing  factors 
which  may  exist.  It  is  very  evident  that  the  treatment  of  such 
cases  will  be  facilitated  and  the  chances  of  success  greatly  enhanced 
if  the  general  and  constitutional  factors  involved  be  recognized  and 
corrected,  concurrent  with  the  local  treatment.  A  neglect  of  the 
systemic  causes  which  lie  behind  these  local  degenerative  processes" 
frequently  results  in  the  failure  and  inability  of  local  measures  to 
control  the  disease. 

In  view  of  this  wide  range  of  local  and  constitutional  factors  which 
may  enter  into  the  various  cases  of  pyorrhea  it  will  be  recognized  that 
this  disease  is  an  extraordinarily  complicated  and  involved  process. 
As  each  may  be  the  product  of  any  or  all  of  these  causative  factors,  it 
follows  that  almost  an  infinite  number  of  combinations  may  be  formed 
which  may  militate  against  the  health  and  integrity  of  the  peridental 
tissues.  Pyorrhea,  as  has  been  previously  stated,  is  not  uniform  nor 
constant  in  its  manifestations  but  presents  many  phases  and  variations 
in  its  course.  Success  in  treating  and  controlling  these  conditions  is 
dependent  upon  the  recognition  of  the  most  predominating  factors  in 
each  case,  and  the  institution  of  measures  which  will  either  remove 
these  determining  causes  or  reduce  them  to  a  state  of  inefficiency.  To 
accomplish  this  a  close  study  of  the  various  cases  which  are  presented 
must  be  made  and  methods  of  diagnosis  must  be  established  by  which 
the  various  types  of  pyorrhea  may  be  recognized  and  classified  to  the 
end  that  intelligent  treatment  may  be  instituted  to  control  the  disease. 

Diagnosis. — ^The  means  by  which  the  type  and  severity  of  various 
cases  of  pyorrhea  may  be  determined  consist  of  certain  local  symptoms 
and  disease  manifestations  associated  with  the  state  of  general  health 
of  the  patient.  The  primary  symptoms  may  be  classified  into  four 
definite  groups  namely,  changes  in  color,  form,  and  density  of  the  gums 
and  their  attachment  to  the  necks  of  the  teeth.  These  are  supple- 
mented by  secondary  or  more  advanced  local  symptoms  such  as  the 


DIAGNOSIS 


555 


loosening  of  the  teeth,  the  presence  of  ])us  and  roentgenographic  evi- 
dence, together  with  a  consideration  of  the  general  systemic  condi- 
tions. It  is  by  the  proper  interpretation  of  these  sjinptomatic  changes 
that  the  various  types  of  pyorrhetic  affection  may  be  analyzed  and 
classified. 

Changes  in  Color. — The  color  of  the  normal  gum  tissues  varies  in 
different  individuals  from  light  to  dark  shades  of  pink,  but  in  all  cases 
the  color  is  uniform  tlu-oughout  (Fig.  430).  This  color  is  the  reflection 
of  the  hemoglobin  of  the  blood  in  the  capillaries  which  lie  immediately 
beneath  the  mucous  membranes  while  the  depth  of  the  color  is  deter- 
mined by  the  amount  and  quality  of  the  blood  in  the  vessels.  In  full 
blooded  individuals  the  submucous  circulation  is  filled  with  red  blood 
which  gives  a  deep  pink  or  dark  red  color  to  the  gum  tissues.  In  con- 
trast to  these  the  anemic  and  undernourished  t^^pes  have  a  less  amount 


Fig.  430. — Normal,  healthy.gums. 


of  blood  in  the  peripheral  circulation,  the  hemoglobin  content  is  usually 
low  and  the  color  of  the  gum  tissues  is  normally  a  light  shade  of  pink 
(Fig.  431).  Thus  we  may  read  in  the  general  gum  color  many  interest- 
ing and  important  facts  concerning  the  general  health  and  the  character 
of  the  general  circulation. 

Any  localized  deviation  from  that  uniform  color  which  is  t^'pical  to 
an  individual  is  indicative  of  local  changes  in  the  circulation.  Darker 
shades  of  red  usually  denote  hyperemia,  the  depth  of  the  color  depend- 
ing upon  the  severity  of  the  circulatory  distiubance.  Deep  red  and 
blue  (Fig.  432)  are  indicative  of  stasis  and  passive  congestion  and  an 
engorgement  of  the  submucous  circulation  with  venous  blood.  These 
localized  changes  in  the  gum  color  should  be  to  the  operator  a  signal  of 
danger  for,  as  a  result  of  the  circulatory  derangement,  these  tissues 
mil  suffer  from  a  lack  of  nourishment  and  will  lose  their  normal  tone 
and  resistive  power.     It  may  also  be  noted  that  in  the  vicinity  of  these 


556 


PYORRHEA  ALVEOLARIS 


color  changes  some  form  of  irritant,  either  chemical,  bacterial  or 
mechanical,  may  be  found  which  is, producing  an  active  injury,  upon 
the  removal  of  which  the  color  of  the  tissues,  as  a  rule,  promptly  returns 


Fig.  431. — Pale  anemic  gums,  evidence  of  poor  circulation. 


Fig.  432. — Localized  change  of  color  between  upper  central  incisors,  deep  red  to  purple, 
indicative  of  localized  irritation  at  that  point. 


Fig.  433. — Gingivae  highly  inflamed  and  congested  in  response  to  some  foim  of  local- 
ized irritation.  Indicative  of  strong  protective  tissue  reaction  and  as  a  rule  responds 
readily  to  treatment. 

to  normal.  By  experience  one  may  also  read  in  these  gima  colors  the 
types  of  protective  reaction  which  are  put  forth  by  the  tissues  to  com- 
bat the  injury.  In  those  cases  in  which  the  tissues  are  red  and  give 
evidence  of  strong  inflammatory  reaction  (Fig.  433)  it  will  be  found 


DIAGNOSIS 


557 


that  the  pyorrheal  invasion  advances  slowly  and  that  when  the  irrita- 
tions have  been  removed  the  tissues  show  a  rapid  recuperative  power. 
Conversely,  when  the  guin  colors  are  pale  or  dark  blue  (Fig.  421)  the 
reactions  are  less  complete,  the  invasion  is  more  rapid  and  a  cure 
more  difficult  to  obtain.  Color  changes,  therefore,  constitute  a  very 
important  diagnostic  factor  in  the  discovery  of  pyorrhea  and  in  the 
evaluation  of  the  local  tissue  reactions. 

Changes  in  Form. — ^Normally  the  gum  contour  about  the  teeth  follows 
that  of  the  edge  of  the  enamel  at  the  neck  of  the  tooth  which  it  slightly 
overlaps.  In  the  interproximate  it  extends  up  to  the  point  of  contact 
completely  filling  the  space  between  the  adjacent  teeth.  Deviations 
from  the  normal  are  of  two  types,  namely,  shrinkage  or  retraction  of  the 
gum  line,  and  swelling  or  h}^7)ertrophy  of  these  tissues.  Examples  of 
the  former  may  be  seen  in  the  retretction  of  the  buccal  or  lingual 


Fig.  434. 


-Loss  of  interproximate  bone  and  gum  tissues  in  beginning  pyorrhea. 
Reaction  poor. 


contours  due  to  tooth  brush  abrasions  or  to  the  atrophy  of  old  age. 
So  also,  the  gingival  tissues  are  retracted  as  a  result  of  deep  pyorrheal 
involvement.  A  slight  retraction  of  the  interproximate  tissues  is  sho\^^l 
in  Fig.  434,  and  a  more  severe  involvement  in  Fig.  435.  Swelling  of 
the  gum  tissues  about  the  teeth  frequently  occurs  (Fig.  436)  in  the 
early  stages  of  gingivitis  and  pyorrhea.  It  is  indicative  of  strong 
inflammatory  reaction  and  usually  denotes  a  high  degree  of  resistance 
and  recuperative  power.  As  in  the  case  of  color  changes  one  may  also 
read  in  the  behavior  of  the  gum  contours  the  t;^^e  of  tissue  reactions  to 
various  irritations.  When  their  tendency  is  to  shrink  and  retract  it 
may  be  inferred  that  the  resistance  of  the  tissues  is  low  and  that 
degenerative  changes  are  easily  induced.  But  when  in  response  to 
injury  the  tissues  swell,  especially  if  the  color  is  bright  red,  the  local 
tissue  reactions  are  usually  of  good  order  and  highly  resistant  to 
pyorrhetic  invasion. 


558  PYORRHEA  ALVEOLARIS 

Changes  in  Density. — ^The  normal  gum  tissues  are  hard,  firm  and 
resistant  to  mechanical  injuries.  The  mucous  membrane  is  tightly 
stretched  over  an  underlying  dense  connective  tissue  which  is  sup- 
ported by  the  alveolar  process.  This  epithelium  is  so  tough  that  in 
the  act  of  vigorous  mastication  and  brushing  of  the  teeth  no  abrasion 


Fig.  435. — Extensive  loss  of  alveolar  bone  and  retraction  of  gingiva;  in  advanced  pyorrhea 
(case  treated  and  under  control  at  time  picture  was  taken) . 

or  hemorrhage  of  the  soft  tissues  will  occur.  But  when  the  gum  tissues 
are  soft,  spongy,  and  bleed  easily  as  the  result  of  slight  injuries  they  are 
no  longer  normal  or  in  health.  This  latter  condition  is  indicative  of 
chronic  inflammation  or  general  bodily  disturbance  and  tissues  so 
affected  are  often  highly  susceptible  to  pyorrhetic  infection. 


Fig.  436. — Gingivitis,  hypertrophic  type,  indicative  of  strong  tissue  reactions. 

The  Line  of  Attachment. — ^Normally  the  gum  tissues  are  firmly 
attached  about  each  tooth  to  the  peridental  membrane  at  the  bottom 
of  a  shallow  gingival  crevice.  When  by  exploration  it  is  determined 
that  this  normal  attachment  has  been  disturbed  and  that  a  space 
exists  between  the  root  and  the  surrounding  peridental  tissues,  it  is 
evident  that  the  tissues  have  suffered  some  form  of  injury  which  in  the 


DIAGNOSIS  559 

great  majority  of  cases  is  pyorrheal  in  type.  No  matter  how  much 
inflammation  and  swelhng  may  be  present  in  the  superficial  and 
gingival  tissues  true  pyorrhea  does  not  exist  as  long  as  the  line  of 
attachment  of  the  soft  tissues  about  the  root  remains  normal.  The 
crucial  test  of  pyorrhea  consists,  therefore,  in  the  careful  exploration  of 
all  gingival  crevices  to  determine  whether  or  not  definite  breaks  in  the 
normal  line  of  attachment  have  been  effected.  This  is  the  most  impor- 
tant and  the  most  certain  method  of  diagnosing  pyorrhea. 

Loosening  of  the  Teeth. — It  is  only  in  the  more  advanced  and  severe 
cases  of  pyorrhea  that  the  teeth  become  loosened.  Because  pyorrheal 
lesions,  as  a  rule,  are  confined  to  but  one  or  two  sides  of  the  teeth  and 
tend  to  extend  apically  along  the  sides  of  the  roots  rather  than  about 
them,  deep  lesions  may  be  produced  about  teeth  which  still  possess 
sufficient  peridental  attachment  to  hold  them  securely  in  position. 
When  by  reason  of  extension  of  the  disease  one  or  more  of  the  teeth 
becomes  loose,  it  may  be  inferred  that  the  condition  is  very  serious  and 
the  possibility  of  successful  treatment  of  these  teeth  is  doubtful.  The 
loss  of  stability  on  the  part  of  a  tooth  may  arise  either  from  a  rapid  and 
extensive  destruction  of  the  peridental  membrane  by  which  the  attach- 
ment of  the  root  is  cut  off  from  the  surrounding  alveolar  bone,  or  from 
a  disintegration,  or  a  metaplasia  of  the  bone  to  fibrous  tissue  by  which 
the  attachment  of  the  tooth  becomes  wholly  fibrous  and  unfirm.  The 
prognosis  in  case  of  a  loosened  tooth  depends  upon  the  type  of  degenera- 
tive process  which  has  occurred.  When  there  is  only  a  moderate  degree 
of  movement  and  by  roentgenographic  evidence  it  is  determined  that  at 
least  the  apical  half  of  the  root  is  embedded  in  bone^  if  other  conditions 
permit,  treatment  may  be  attempted.  But  when  on  percussion  the 
tooth  plays  up  and  down  or  may  be  rotated  in  its  socket,  and  the 
roentgenographic  findings  show  that  the  surrounding  bone  has  been 
destroyed,  treatment,  as  a  rule,  is  contra-indicated.  In  this  latter  case 
the  successful  cure  of  the  disease  would  involve  not  only  the  healing 
of  the  lesions  and  a  reattachment  of  the  tissues  to  the  teeth,  but  also 
a  regeneration  of  sufficient  bone  to  give  stability  to  the  root.  This 
result  may  be  obtained  occasionally  in  young  and  healthy  individuals 
under  most  favorable  circumstances,  but  should  never  be  hoped  for 
when  systemic  derangement  exists  or  in  patients  past  middle  life. 

Pus. — The  presence  of  pus  has  been  used  by  many  as  an  important 
and  specific  means  of  diagnosing  pyorrhea.  But  as  we  have  previously 
pointed  out,  pus  is  not  a  specific  feature  of  pyorrhea  inasmuch  as  a 
large  majority  of  pyorrheal  lesions  have  no  visible  purulent  discharge. 
The  only  information  that  may  be  derived  from  pus  is  that  the  pre- 
dominating organisms  are  of  the  purulent  type  and  that  against  them 
the  tissue  reactions  are  of  good  order.     Instead  of  being  a  symptom  of 


560  PYORRHEA  ALVEOLARIS 

grave  significance,  pus  is  an  indication  that  the  tissues  are  combating 
the  infection  and  perhaps  controlUng  it  and  that  in  view  of  the  active 
local  reaction  the  prognosis  of  treatment  of  such  a  case  is  favorable. 

Roentgenogra'phic  Findings. — ^There  are  many  roentgenographers  who 
claim  that  they  are  able  to  diagnose  all  stages  of  pyorrhea  by  the  roent- 
genogram, but  in  our  experience  this  form  of  diagnosis  is  accurate  and 
valuable  for  only  one  phase  of  the  process,  namely,  the  extent  of  bone 
destruction.  In  all  other  questions  regarding  a  pyorrheal  involvement 
one  may  be  easily  misled  by  roentgenographic  evidence;  as  for  instance, 
it  is  difficult  and  often  impossible  by  these  means  alone  to  differentiate 
between  an  active  pyorrheal  state  and  a  healed  lesion  of  the  disease. 
An  opinion,  therefore,  regarding  a  case  of  pyorrhea,  should  never  be 
formulated  from  the  evidence  of  a  roentgenographic  film  alone,  but 
rather  should  all  other  means  of  diagnosis  be  employed  in  which  the 
roentgenogram  is  but  one  factor.  From  the  roentgenogram  a  more  or 
less  accurate  idea  of  the  amount  of  bone  destruction  may  be  obtained. 
In  this  also  there  is  a  possible  source  of  error  in  that  destruction  of  the 
interproximate  bone  may  take  place  to  produce  a  hole  or  cup-shaped 
depression  between  two  adjacent  teeth,  while  the  labial  and  lingual 
plates  are  still  intact,  in  which  case  the  exact  status  of  the  osseous 
lesion  is  not  easily  determined  by  the  roentgenogram.  So  also  the 
destruction  of  bone  on  either  the  labial  or  lingual  aspects  of  the  tooth 
may  not  be  apparent  when  the  opposite  bony  walls  are  unaffected,  as 
the  shadow  of  the  healthy  portion  obscures  the  outline  of  that  which  is 
diseased.  Too  much  dependence  should  not  be  placed  on  the  roent- 
genogram in  the  diagnosis  of  pyorrhea,  but  rather  should  it  be  employed 
only  as  an  auxiliary  and  a  subordinate  factor  in  the  whole  chain  of 
evidence. 

General  Considerations. — In  every  case  that  is  presented  the  first  ques- 
tion to  be  determined  is  whether  treatment  should  be  attempted  or 
extraction  prescribed.  By  means  of  the  foregoing  methods  of  diagnosis 
accurate  information  may  be  obtained  regarding  the  local  conditions, 
but  this  alone  will  not  suffice.  As  we  have  previously  attempted  to 
point  out,  no  disease  should  be  considered  as  a  local  process  independent 
of  general  and  bodily  states.  The  diagnosis  and  treatment  of  pyorrheal 
affections  should  not  be  made  without  a  careful  and  thorough  con- 
sideration of  the  general  health,  age,  temperament,  occupation,  environ- 
ment and  personal  characteristics  of  the  patient.  This  is  especially 
true  in  those  cases  in  which  the  systemic  health  is  an  active  factor  in 
the  disease.  As  a  rule,  treatment  is  contra-indicated  in  patients  who 
are  in  ill  health,  especially  if  their  disabilities  are  of  an  infective  type. 
Whenever  treatment  is  attempted  in  such  cases  the  possibility  of  the 
pyorrheal  infections  being  foci  of  general  infection  should  always  be 


TREATMENT  561 

clearly  borne  in  mind  and  if  a  prompt  improvement  of  the  local  and 
general  distm'bances  is  not  obtained,  all  suspected  teeth  should  immedi- 
ately be  extracted.  On  the  other  hand,  if  the  general  health  is  good 
and  all  other  conditions  are  favorable,  many  severe  and  advanced 
cases  of  pyorrhea  may  be  treated  and  the  lesions  successfully  healed. 
The  decision  concernmg  the  expediency  of  treatment  of  any  individual 
case  of  pyorrhea  should  be  determined  very  largely  by  the  general 
systemic  status  of  the  patient  and  all  contributing  influences  which 
may  help  or  hinder  the  favorable  outcome  of  such  treatment.  To  this 
end  many  operators  insist  that  all  patients  submit  to  a  complete 
physical  diagnosis  before  treatment  is  attempted,  and  in  many  instances 
such  a  course  is  highly  desirable  but  in  a  large  nrmaber  of  cases  a  fairly 
accm-ate  opinion  of  the  general  health  may  be  obtained  by  a  few  well 
directed  questions  and  the  general  appearance  of  the  patient. 

Treatment. — Any  consideration  of  the  treatment  of  pyorrhea  should 
be  preceded  by  a  clear  conception  of  what  benefits  may  reasonably  be 
expected  to  result  from  such  remedial  measm-es.  The  statement 
frequently  has  been  made  by  many  writers  that  pyorrhea  cannot  be 
ciu-ed  and  this  opinion  still  obtains  in  the  minds  of  many  practitioners 
today.  If  by  cm'e  is  meant  the  healing  of  the  lesions  of  the  disease  and 
the  complete  restoration  of  all  lost  tissues  by  structm-es  that  are 
identical  with  the  original  tissues,  it  is  true  that  severe  and  advanced 
cases  of  pyorrhea  in  which  a  considerable  portion  of  the  ah'eolar 
process  and  the  overljdng  tissues  are  lost,  cannot  be  cured.  But  if  a 
permanent  arrest  of  the  disease,  and  a  healing  of  the  lesions  by  a 
reattachment  of  the  soft  tissues  about  the  teeth  at  a  lower  level  on  the 
roots  be  considered  a  cm*e,  then  a  large  percentage  of  cases  of  pyorrhea 
may  be  cured.  The  condition  is  quite  similar  to  that  of  a  deep  ulcera- 
tion in  any  part  of  the  body  which  by  treatment  is  checked  but  in  the 
process  of  healing  a  defect  is  left  because  of  an  incomplete  restoration 
of  the  lost  tissues.  In  either  case  the  disease  is  stopped  and  the  lesions 
have  healed  but  in  case  the  conditions  which  caused  the  first  appearance 
of  the  disease  shall  subsequently  obtain,  the  lesions  may  reappear. 
If  on  the  contrary,  ordinary  hygienic  measm-es  be  established  by  which 
the  causative  factors  are  continuously  removed  or  made  ineffective, 
the  cure  of  the  disease  is  permanent. 

This  is  actually  what  does  happen  in  a  large  majority  of  cases  of 
pyorrhea,  when  a  rational  treatment  has  been  employed  followed  by  a 
regime  of  oral  prophylaxis.  By  the  complete  removal  of  all  local 
irritants  a  prompt  reduction  of  circulatory  disturbances  such  as  hyper- 
emia, congestion  and  inflammation,  is  usualh'  obtained.  When,  by 
fiu-ther  operative  procedm*es,  all  denuded  root  sm"faces  are  planed 
smooth  to  the  bottom  of  the  pockets  the  siurounding  tissues  usually 
36 


562  PYORRHEA  ALVEOLARIS 

may  be  made  to  reattach  themselves  to  the  cementum,  thereby  com- 
pletely obliterating  the  pocket.  In  time  the  soft  tissues  about  the  teeth 
become  hard,  firm  and  highly  resistant  to  infection  and  traumatic 
injuries  and  as  long  as  this  state  of  oral  hygiene  is  maintained  the  like- 
lihood of  a  return  of  the  pyorrheal  infection  is  very  remote. 

Considerable  skepticism  has  been  voiced  by  a  number  of  writers 
concerning  the  possibility  of  a  reattachment  of  the  soft  tissues  about 
a  pyorrheal  pocket  to  the  "pus-soaked  cementum"  of  the  root.  Many 
of  these  writers  have  emphatically  stated  their  unqualified  opinion 
that  this  has  never  occurred  and  that  it  is  impossible  of  accomplish- 
ment. The  actual  histologic  proof  that  healing  of  this  order  has  taken 
place  in  a  pyorrheal  pocket  is  difficult  to  obtain,  as  patients  are  unwill- 
ing to  part  with  a  tooth  that  has  been  successfully  treated  in  this 
manner.  But  clinically  there  is  an  abundance  of  evidence  to  convince 
any  fair  minded  and  unprejudiced  observer.  Personally  we  have  seen 
cases  without  number,  under  our  own  care  and  in  the  hands  of  many 
others,  in  which  deep  pockets  freely  exuding  pus  and  extending  two- 
thirds  and  even  three-quarters  of  the  length  of  the  root,  in  response  to 
operative  measures  gradually  became  more  shallow,  filling  in  at  the 
bottom  day  by  day  until  the  tissues  were  fully  attached  up  to  the  free 
edge  of  the  gum  margin,  save  a  gingival  crevice  of  normal  depth.  It  is 
argued  by  the  oppositionists  that  this  is  not  a  true  attachment  but 
merely  a  close  coaption  of  the  hard  and  soft  tissues  without  a  physical 
union.  To  this  we  may  reply  that  in  cases  in  which  healing  has  taken 
place,  if  an  exploration  be  made  with  a  smooth  nerve  broach  in  a 
gingival  crevice  at  which  point  a  pyorrheal  lesion  previously  existed, 
no  entrance  can  be  effected  and  if  pressure  be  exerted,  blood  flows  and 
the  patient  winces  from  pain.  There  is,  indeed,  no  example  to  be  found 
in  any  other  part  of  the  body  in  which  the  hard  and  soft  tissues  have 
so  closely  coapted  without  physical  union.  Furthermore,  in  case  of 
implanted  porcelain  roots  we  see  excellent  examples  of  coaption  of 
tissues  without  physical  union  but  in  all  of  these  an  instrument  may  be 
readily  passed  between  the  tooth  and  soft  tissues  at  any  point.  We 
recognize  the  fact  that  this  perfect  healing  of  pyorrheal  lesions  may  not 
always  be  obtained  since  in  many  cases  it  is  not  possible  to  completely 
prepare  all  affected  root  surfaces  or  the  vitality  of  the  surrounding 
tissues  may  be  so  low  that  regeneration  does  not  take  place.  But  we 
are  confident  that  when  conditions  are  favorable  and  the  operative 
procedures  have  been  completely  performed,  a  physical  reattachment 
of  the  soft  tissues  to  the  root  to  obliterate  the  pyorrheal  pocket  does 
take  place  in  a  large  percentage  of  cases.  When,  by  severe  involve- 
ment, the  interproximate  gum  tissues  and  the  buccal  and  lingual  con- 
toius  have  been  considerably  deflected,  it  must  not  be  expected  that 


TREATMENT 


563 


these  tissues  will  regenerate  along  the  root,  crownwise,  to  assume  their 
old  positions  except  in  young  individuals  when  the  recuperative  power 
is  high.  As  a  rule,  all  that  may  be  obtained  is  a  healing  of  these  tissues 
and  an  attachment  to  the  roots  of  the  teeth  at  their  present  position. 
Indeed,  during  the  treatment,  the  gums  may  shrink  down  about  the 
teeth  to  a  lower  level  on  the  roots  because  of  a  reduction  of  swellings 
and  circulatory  disturbances  (Fig.  437). 

It  will  be  recognized  that  the  greatest  success  in  the  treatment  of 
pyorrhea  is  to  be  obtained  in  the  early  stages  of  the  disease.  At  this 
time  the  destruction  has  not  been  severe  and  if  the  remedial  measures 
are  properly  applied  the  disease  may  be  checked  promptly  and  the 
tissues  restored  to  approximate  normality.  Could  all  cases  of  pyorrhea 
be  treated  in  their  incipient  stages  the  handling  of  this  disease  would 
be  a  simple  matter.     But  when  the  process  has  advanced  to  the  point 


Fig.  437. 


-Before  and  after  treatment  of  case  of  advanced  pyorrhea,  showing  retraction 
of  gingival  line  after  reduction  of  peridental  inflammation. 


where  deep  lesions  are  effected  in  the  peridental  tissues  and  the  alveolar 
bone  has  degenerated,  the  treatment  is  much  more  complicated  and 
the  chances  of  success  greatly  reduced.  In  the  treatment  of  these 
more  advanced  cases  care  should  be  taken  not  to  attempt  the  impos- 
sible. When  the  general  health  and  bodily  resistance  are  low  or  indica- 
tions of  severe  general  infections  are  present  all  seriously  affected  teeth 
should  be  extracted  at  the  outset.  Seldom  is  it  advisable  to  attempt 
treatment  of  lesions  which  extend  more  than  two-thirds  of  the  distance 
to  the  apex  of  the  root.  Treatment  is  also  ill-advised  when  the  tooth 
plays  up  and  down  in  its  socket  or  may  be  rotated  by  pressm-e.  So 
also,  when  by  roentgenographic  evidence  it  is  determined  that  there  is 
not  sufficient  bone  remaining  about  the  apex  of  the  root  to  support  the 
tooth,  successful  treatment  cannot  be  hoped  for  except  in  very  young 
and  favorable  individuals. 
Treatment  of  pyorrhea,  therefore,  should  be  attempted  only  after  a 


564  ■     PYORRHEA  ALVEOLARIS 

careful  prognosis  has  been  made,  taking  into  account  the  extent  of  the 
local  destruction,  the  type  of  local  reaction,  and  the  age,  general  health 
and  the  probable  cooperation  of  the  patient  in  carrying  out  the  oral 
hygienic  measiu-es.  When  conditions  are  favorable,  highly  satisfactory 
results  may  be  obtained  by  proper  operative  and  prophylactic  measures; 
but  when  the  attending  conditions  are  unfavorable  or  the  disease  is  too 
far  advanced,  attempted  treatment  is  certain  to  result  in  disappoint- 
ment and  failure. 

The  method  of  treatment  of  those  cases  of  pyorrhea  which  in  the 
light  of  careful  diagnosis  show  promise  of  a  satisfactory  result,  is  largely 
that  of  the  application  of  the  principles  set  forth  in  Chapter  III  and  the 
extension  of  these  procedures  to  include  the  surfaces  of  the  roots  which 
have  been  denuded  of  their  normal  pericemental  attachments.  It  must 
be  recognized  that  in  all  cases  of  pyorrhea  the  general  bacterial  flora  of 
the  mouth  is  abnormal  and  the  first  step  in  the  process  is  to  decrease 
and  change  the  t^-pe  of  oral  fermentations.  To  this  end  thorough  and 
rigorous  prophylactic  measures  should  be  employed  to  rid  the  mouth 
of  all  foreign  and  harmful  agencies.  All  calculi  and  foodstuffs  should 
be  removed  from  the  crowns  of  the  teeth  and  between  the  teeth,  and 
all  rough  enamel  surfaces  should  be  smoothed  so  that  they  may  be  kept 
clean.  It  is  advisable  to  remove  all  ill-fitting  crowns  and  bridges 
which  irritate  the  soft  tissues  or  tend  to  harbor  food  materials  beneath 
them.  All  fillings  which  overhang  their  margins  should  be  trimmed 
down  until  they  are  flush  with  the  enamel  surfaces.  In  case  of  proxi- 
mate fillings  which  do  not  have  proper  contacts  with  the  adjacent 
teeth  the  defect  should  be  remedied  or  the  filling  replaced.  All  open 
cavities  should  be  filled,  if  not  permanently  at  least  with  a  temporary 
stopping. 

When  these  general  prophylactic  measures  have  been  carefully 
performed,  the  next  step  should  be  that  of  equalizing  occlusal  stresses 
of  all  the  teeth.  By  the  use  of  carbon  paper  the  points  of  greatest 
stress  may  be  located  and  by  judicious  grinding  with  stones  any  undue 
and  excessive  stress  of  one  tooth  upon  another  may  be  relieved.  In 
this  manner  teeth  which  are  severely  affected  by  pyorrhea  may  be 
lightened  of  their  occlusal  load  and  the  stress  of  mastication  shifted 
back  to  other  teeth  which  are  more  able  to  bear  the  burden.  This 
feature  of  the  process  is  highly  important  to  the  successful  treatment  of 
the  disease.  When  all  of  the  foregoing  procedures  have  been  carried 
out  the  mouth  and  teeth  are  ready  for  the  special  treatment  of  the 
pyorrheal  lesions. 

This  treatment  should  consist  in  suitable  operative  procedures  by 
which  the  denuded  cemental  surfaces  may  be  completely  cleansed  of 
all  calculi  and  foreign  materials  and  subsequently  planed  to  a  smooth 


TREATMENT 


505 


homogeneous  surface.  It  nuist  l)e  remembered  that  the  outer  surface 
of  the  cementum  is  rough  and  pitted  by  reason  of  the  apertures  in  which 
are  embedded  the  broken  ends  of  the  peridental  fibers.  If  the  outer 
cemental  surface  be  allowed  to  remain,  its  pitted  surface  offers  an 
admirable  retention  for  bacterial  growths,  the  organisms,  thriving 
like  cave  dwellers  in  the  side  of  a  cliff  from  which  they  come  forth  at  a 
future  time  to  attack  the  surrounding  tissues.  If  by  careful  planing 
this  outer  pitted  surface  be  slightly  reduced,  a  deeper  and  more  homo- 
geneous layer  is  reached  which  offers  little  retention  to  infectious 
organisms.  But  in  the  reduction  of  this  surface  great  care  must  be 
exercised  not  to  cut  too  deeply,  for  the  cementum  on  the  lateral  surface 
of  the  root  is  thin  and  with  little  effort  a  sharp  instrument  improperly 


D 


A   — 


B 


^sn^^^esssm. 


^■:\A.  :r ^ 


*•  ' 


iiMi!ij.yiiii;, ...... ,..,-..•   jjiii 


Fig.  438. — Cross-section  of  root  carefully  smoothed  with  files.  D,  dentin;  T,  granular 
layer  of  Tomes;  C,  cementum;  4,  portion  of  cementum  not  touched  with  files;  B,  portion 
of  root  filed,  showing  removal  of  cementum  and  cutting  into  the  dentin. 


applied  will  cut  through  the  cementum  and  the  homogeneous  layer  which 
lies  below  into  the  granular  layer  of  Tomes  on  the  periphery  of  the  dentin 
(Figs.  438,  439  and  440).  When  this  unfortunate  result  has  occiu-red 
the  surface  so  cut  can  never  be  made  smooth  but  will  be  deeply  pitted 
by  spaces  opening  directly  into  the  dentinal  tubuli  in  which  the  pyor- 
rheal  infections  may  find  a  permanent  habitation  to  prevent  the  success- 
ful healing  of  the  lesion.  It  is  therefore  of  the  highest  importance 
that  in  the  operation  of  preparing  the  root  surfaces  too  much  cementiun 
should  not  be  removed,  but  rather  should  these  surfaces  be  carefully 
and  evenly  smoothed  until  by  the  sense  of  touch  transmitted  through 
the  instrument  it  is  determined  that  a  homogeneous  siu^face  has  been 
obtained  and  then  all  further  reduction  at  that  point  should  cease. 
This  operation  may  be  accomplished  by  the  various  types  of  instru- 


566 


PYORRHEA  ALVEOLARIS 


ments  described  on  p.  153  which  should  be  used  in  the  manner  outHned 
for  preventive  dentistry.     In  each  case  an  instrument  should  be  selected 


D. 


iV-  -•• 


—  H'^-. 


>  ■"•1 


f 


Fig.  439. — Cross-section  of  root  smoothed  with  Younger  type  of  instrument.  D,  dentin ; 
T,  granular  layer  of  Tomes ;  C,  cementum  which  has  not  been  appreciably  reduced  by 
the  instrumentation. 

which  best  adapts  itself  to  the  position  upon  the  root  it  is  desired  to 
reach  and  then  the  blade  should  be  carefully  introduced  beneath  the 


Fig.  440. — -Cross-section  of  root  smoothed  with  planing  instruments.  D,  dentin; 
T,  granular  layer  of  Tomes ;  C,  cementum ;  A ,  portion  of  root  not  touched  with  the  planers ; 
B,  portion  of  root  planed,  showing  reduction  of  cementum  nearly  to  cemento-dental 
junction. 


gum  to  the  bottom  of  the  pocket  to  plane  the  surface  of  the  root  with 
a  draw  motion,  crownwise,  until  the  root  is  smooth. 


TREATMENT  '  567 

The  operative  treatment  of  pyorrhea  should  not  be  done  in  a  hit  or 
miss  manner  but  should  follow  a  consecutive  plan  of  procedure  which  is 
directed  toward  a  definite  object  to  be  attained.  This  object  is  the 
surgical  cleansing  and  smoothing  of  every  surface  of  each  denuded 
root  and  the  reduction  of  the  infective  organisms  to  the  point  that  the 
resistance  of  the  tissues  may  gain  ascendency  over  them.  To  this  end 
the  operative  procedures  should  begin  in  one  corner  of  the  mouth,  for 
instance  the  last  upper  right  molar,  and  progress  tooth  by  tooth  about 
the  mouth  until  all  are  surgically  clean.  Each  tooth  should  be  finished 
before  another  is  attempted  and  if  the  surfaces  are  properly  prepared 
it  should  not  be  necessary  to  do  any  further  instrumentation  upon 
them  other  than  the  cleansing  of  the  pockets  as  will  be  described  later. 

In  view  of  the  fact  that  this  form  of  treatment  is  a  careful  exacting 
operation  and  is  more  or  less  painful  to  the  patient  it  is  always  wise  to 
make  the  appointments  short,  not  more  than  thirty  to  forty-five  minutes 
to  be  repeated  each  successive  day,  treating  but  two  or  three  teeth  at 
each  sitting  until  all  have  been  covered.  In  cases  of  highly  infective 
type  in  which  the  tissue  resistance  is  low  the  treatment  of  only  a  few 
teeth  is  a  distinct  advantage.  It  is  noted  that  operation  upon  these 
highly  infective  types  of  pyorrhea  frequently  is  followed  by  a  distinct 
shock.  As  a  result  of  the  operative  procedures  the  protective  tissue 
wall  about  the  infection  is  broken  down  and  through  the  surgical 
wounds  that  are  produced  a  quantity  of  infectious  organisms  and  their 
products  are  introduced  directly  into  the  circulation.  Consequently, 
fever  and  general  bodily  disturbances  may  follow  drastic  treatment 
of  too  many  pyorrheal  lesions  at  any  one  sitting.  When  only  a  few 
such  lesions  are  operated  upon,  the  general  effects  are  usually  less 
marked  or  are  insignificant. 

When  a  surgeon  operates  in  a  sterile  field  he  closes  the  wound  and 
does  not  disturb  it  unless  infection  subsequently  sets  in.  But  when  the 
wound  is  on  a  surface  that  necessarily  must  be  reinfected  and  cannot 
be  kept  sterile,  he  washes  and  dresses  the  wound  daily  until  healing 
has  taken  place.  Operations  on  pyorrheal  tissues  are  of  this  second 
type,  in  that  the  wound  is  constantly  open  to  oral  infections,  food 
materials,  and  other  foreign  substances  which  irritate  the  tissues  and 
miHtate  against  their  healing. 

Of  special  significance  in  this  regard  are  the  fine  subgingival  calculi 
which  are  laid  down  upon  the  roots  of  teeth  in  a  pyorrheal  lesion 
subsequent  to  operation  upon  them.  It  is  frequently  noted  that 
although  the  root-surfaces  may  have  been  thoroughly  planed  and 
smoothed  at  one  sitting,  the  next  day  a  new  deposition  of  calculi  may 
be  found  beneath  the  gum  line  which  will  continue  the  irritation  to  the 
surrounding  soft  tissues  and  prevent  their  healing.     The  som-ce  of 


568  PYORRHEA  ALVEOLARIS 

these  rapidly  forming  calculi  is  not  definitely  known,  but  it  is  probable 
that  they  are  an  inflammatory  exudate  of  the  diseased  tissues.  When 
by  prophylactic  measures  the  peridental  inflammation  has  been 
reduced  and  the  tissues  have  assumed  their  normal  color  and  density 
this  tendency  to  form  subgingival  calculi  is  terminated.  It  is  therefore 
necessary  at  each  daily  sitting  to  go  about  the  teeth  which  have  pre- 
viously been  treated  and  carefully  enter  the  pockets  to  remove  any 
foreign  materials  and  infectious  matter  from  them,  extreme  caution 
being  taken  not  to  tear  down  the  new  peridental  attachments  which 
have  been  formed  in  the  process  of  healing.  This  may  be  done  with  a 
small  Younger  type  instrument  or  with  dull  files,  after  which  the  pocket 
should  be  flushed  with  a  bland  solution.  When  this  procedure  is  carried 
out  daily  it  will  be  seen  that  day  by  day  the  instrument  may  be  intro- 
duced a  shorter  and  shorter  distance  beneath  the  gum  until  finally  no 
pocket  remains,  healing  having  been  completely  accomplished  from  the 
base  of  the  lesion  up  to  the  gingival  line. 

Thus  as  the  result  of  instrumentation  alone  in  favorable  cases  the 
pus  fiow  may  cease  after  one  treatment  and  by  daily  cleansing  and 
washing  a  complete  attachment  may  be  effected  between  the  teeth  and 
the  peridental  tissues.  As  an  adjuvant  to  these  measures  the  pockets 
may  be  flushed  out  with  a  weak  iodin  or  a  saline  solution.  The  follow- 
ing iodin  lotion  is  admirable  for  this  purpose  as  it  is  antiseptic,  sedative, 
astringent  and  stimulative  in  its  action.     The  formula  is  as  follows: 

Phenol  (5  per  cent.) 1  part 

Aconite  (tinct.) 2  parts 

Iodin  (tinct.) 3     " 

Glycerin 4     " 

This  may  be  introduced  into  the  pockets  with  a  glass  barreled  syringe 
having  a  platinum  point  which  may  be  sterilized  readily  in  the  flame 
(Fig.  441).  In  many  cases  a  5  per  cent,  sodium  chlorid  solution  will 
give  equally  beneficial  results.  This  strength  is  to  be  preferred  over 
the  bland  physiologic  salt  solution  for  the  reason  that  the  hj^pertonic 
salt  in  contact  with  the  tissues  produces  in  them  an  exosmosis  and 
exudations  which  tend  to  wash  the  mucous  surfaces.  Furthermore, 
the  lymph  and  blood  fluids  are  in  this  manner  attracted  to  the  spot 
bringing  many  germicidal  and  immune  principles  to  aid  in  the  reduction 
of  infection. 

It  is  the  opinion  of  the  author  that  no  other  drugs  are  necessary  in 
the  treatment  of  pyorrhea  except  in  rare  cases.  Occasionally  an  old 
tough  granulation  tissue  will  be  found  about  a  chronic  pyorrheal 
pocket  and  when  such  a  tissue  obstinately  refuses  to  heal  after  proper 
instrumentation,  it  may  be  treated  with  phenol-sulphonic  acid  (Merck) . 


TREATMENT  569 

This  may  be  introduced  into  the  pocket  by  means  of  a  thin  wedge  made 
of  bamboo  held  in  a  porte-pohsher. 

As  heahng  takes  place,  the  patient  may  be  seen  less  and  less  fre- 
quently. During  this  time  he  should  be  instructed  in  the  proper 
method  of  caring  for  his  mouth,  encouraged  to  keep  the  tissues  con- 
tinuously clean,  and  to  massage  the  gums  with  the  brush  until  they  are 
hard,  firm  and  highly  resistant.  When  the  case  is  finally  under  control 
and  the  pockets  healed,  the  patient  should  be  requii'ed  to  report  at 
intervals  of  from  one  to  three  months,  depending  upon  the  case,  in 
order  that  he  may  be  assisted  in  the  care  of  his  mouth  and  that  all 
incipient  gum  lesions  may  be  noted  early  in  their  course.  Usually 
these  lesions  may  be  easily  aborted  in  their  incipiency  by  the  removal 
of  the  irritation  which  has  caused  them  and  as  a  result,  the  tissues  are 
readily  restored  to  normal  health.  In  certain  types  of  cases  when  the 
lesions  have  healed  and   the   infections   have   been   eradicated,   the 


Fig.   441. — Syringe  for  washing  out  pyorrheal  pockets. 

tissues  remain  permanently  in  health  and  no  tendency  to  recurrence 
is  evident.  But  in  other  types,  especially  when  the  saliva  is  thick  and 
mucinous,  the  mouth  hygiene  is  not  easily  maintained,  infections  are 
high  and  the  tissue  resistance  is  low.  There  is  in  them  a  constant 
tendency  toward  a  recurrence  of  the  pyorrheal  invasion^  for  the  pre- 
vention of  which  it  is  necessary  to  combat  continuously  the  predisposing 
factors  wdiich  are  present. 

Thus  we  see  that  the  successful  treatment  of  a  given  case  of  pyorrhea 
depends  upon  the  severity  of  the  case,  the  reaction  of  the  local  tissues, 
the  generak  health,  and  the  thoroughness  with  which  the  operative 
procedures  are  performed.  Provided  that  the  first  three  of  these  con- 
siderations are  favorable  the  degree  of  success  is  largely  determined 
by  the  perfection  of  technic  which  is  employed  in  the  sm'gical  pro- 
cedures. Half  way  measures  are  worse  than  none,  for  they  cause 
pain  and  discomfort  to  the  patient  and  result  only  in  failure.     But 


570 


PTOHRHEA  ALTEOLARIS 


careful  and  conscientioTis  study  of  these  conditions  and  the  technic 
involved  to  relieve  them  vrill  enable  the  oi)erator  to  obtain  a  permanent 
healing  and  a  x>otential  cure  of  a  large  majoritj"  of  such  favorable 


Fig.  m; 


rrheal  mvotvemeiit  vith  deep 
rei  "witli  tlifn  scales  of  Iiard, 
11-;    recoTered  after  ocirplete 


Fie. 


--  r  -  nptly  recoTered  after  tltorciiighi  operaave  pro- 


L  T::ream(i  aft^: 


izz  lecoT-ay  fottowing  operative  treatmer: 


TBEATJtEXT 


571 


A  soies  of  eases  wijidi  Imxe  been  tpmted  in  ti*e  maiDUQier  wlakii  iaas 
beem  ootjiiied,  is  shown  in  Fig^-  412  to  451  iniAiMve.  "Haese  cases  hare 
been  sdected  hoaa.  the  cdl^ie  dime  and  fecMii  pnvate  pcactice,  ilie 


Fbs,  155. — Case  ©f  ae^rese 


ihmra  griggnra  afffrgsr  ii«iHMa«wf^iMS.-     ^®  S^ri^eisms  (i€ 


iise.  -sAt. — (Las?  r;  srTjr 
Teass  affttor  Ereaiiiffliieiiii-    E;~ 


within  a  few  weds  ol  eacli  :" 
to  e#ect  a  conqJete  core  buE 


572 


PYORRHEA  ALVEOLARIS 


ment  in  the  clinical  appearance  of  the  case,  the  pyorrheal  invasion  had 
been  stopped,  the  lesions  were  healing  and  the  case  was  e^'idently  under 


Fig.  448. — The  Ht.  Family — Father.  Before  and  after  treatment.  Severe  involve- 
ment, upper  central  incisor  extracted,  case  under  control  one  year  later.  Pictures  taken 
one  month  apart. 


Fig.  449. — -The  Ht.  Family — Mother.   Before  and  after  treatment.    Severe  pyorrhea  with 
mal-occlusion.    Case  under  control  one  year  later.    Pictures  taken  one  month  apart. 


Fig.  450. — -The  Ht.  Family — Daughter,  aged  twenty-one.  Before  and  after  treat- 
ment. Incipient  pyorrhea  which  promptly  yielded  to  treatment.  Pictures  taken  one 
month  apart. 


control.    Many  of  them  when  kept  under  prophylactic  supervision  for 
some  time  continued  to  improve  and  much  of  the  tissue  which  had  been 


PERICEMENTAL  ABSCESS 


573 


lost  in  the  course  of  the  disease  was  restored  by  the  heahng  process. 
Other  cases  which  passed  out  of  supervision  for  over  one  year  were 
still  in  good  condition  and  showed  little  or  no  evidence  of  active 
P3'orrheal  invasion.  Figs.  445,  446  and  447  are  pictures  of  finished  cases 
of  some  five  or  six  years'  standing  which  originally  had  suffered  from 
severe  pyorrhea  but  which  had  shown  no  recurrence  of  that  disease 
since  the  original  operative  treatment.  Figs.  448,  449,  450  and  451  are 
interesting  as  they  were  taken  from  the  members  of  one  family,  namely, 
father,  mother  and  two  daughters,  aged  twenty-one  and  fourteen 
respectively.  Both  father  and  mother  had  severe  cases  of  pyorrhea, 
although  not  of  the  same  type  and  both  daughters  showed  beginning 
pyorrheal  involvement  of  a  type  like  that  of  the  mother. 


Fig.  451. — The  Ht.  Family — Daughter,  aged  fourteen.   Tendency  toward  peridental 
disease  similar  to  elder  sister. 


PERICEMENTAL  ABSCESS. 

In  comparatively  rare  cases,  abscesses  are  formed  on  the  lateral 
surfaces  of  the  roots  of  teeth  which  are  seemingly  unrelated  to  the 
apical  or  gingival  areas.  They  occur  on  teeth  in  which  the  pulps  and 
periapical  areas  are  normal  and  may  or  may  not  be  associated  with 
pyorrhea.  Two  general  classes  of  pericemental  abscesses  may  be 
distinguished:  first,  those  which  are  situated  on  roots  of  teeth  which 
have  been  attacked  by  pyorrhea  and  which  are  virtually  deep  extensions 
of  pyorrheal  lesions  some  distance  down  the  side  of  the  root,  and  second, 
those  which  apparently  are  unaccompanied  by  any  other  peridental 
disease.  In  their  course  they  may  be  marked  by  extensive  inflamma- 
tory changes  and  swelling  or  they  may  develop  in  a  gradual  insidious 
manner  without  pain  or  other  outward  evidence  of  their  presence. 
When  they  are  purulent  in  type,  the  pus  may  burrow  its  way  to  the 
surface  along  the  peridental  membrane  and  be  evacuated  in  the  gingival 
crevice  or  a  pyorrheal  pocket,  or  it  may  penetrate  the  overlying 
submucous  and  mucous  tissues  to  form  a  fistula  on  the  lateral  surface 


574  PYORRHEA  ALVEOLARIS 

of  the  gum  after  the  manner  of  periapical  abscesses.  It  is  difficult  to 
differentiate  abscesses  of  the  first  type  from  true  pyorrheal  lesions 
and  the  latter  type  may  be  easily  confused  with  true  periapical  abscess. 
On  the  surface  of  the  root  corresponding  with  the  initial  point  of  abscess 
formation  the  pericementum  is  denuded  and  usually  a  deposit  of  thin 
plate-like  calculus  may  be  fomid  firmly  adherent  to  the  cementum. 
The  source  of  these  deposits  and  the  deep  infection  in  these  peridental 
tissues  is  not  clear.  Pierce^  found  that  many  of  the  calculi  answered 
to  the  murexid  test  for  urates  from  which  he  concluded  that  they  were 
laid  down  by  the  general  circulation  as  the  result  of  a  uric  acid  diathesis. 
Kirk^  found  that  in  a  number  of  cases  which  he  examined  the  infection 
involved  was  a  pure  culture  of  pneumococcus.  In  many  cases  perice- 
mental abscesses  seem  to  be  deep  and  penetrating  forms  of  pyorrheal 
invasion  in  which  the  infection  having  burrowed  into  the  tissues  some 
distance  beyond  the  apparent  lesion,  has  produced  at  its  farthest  exten- 
sion an  acute  exacerbation  of  tissue  destruction  accompanied  by 
calcareous  deposit.  In  other  cases  they  occur  on  the  roots  of  vital 
teeth  about  which  there  is  no  evidence  of  pyorrheal  involvement. 
This  latter  form  has  been  thought  to  arise  from  systemic  or  constitu- 
tional cause  which  may  be  associated  with  various  local  traumatic 
injuries  such  as  malocclusion,  excessive  stress,  accidents,  etc.  Indeed 
they  seem  to  occur  with  greater  frequency  in  individuals  who  suffer 
from  certain  systemic  distm-bances  as  gout,  diabetes,  Bright's  disease, 
and  other  like  affections.  More  recently  it  has  been  found^  in  cases 
of  faulty  oral  hygiene  when  oral  fermentations  are  high  that  micro- 
organisms, especially  the  streptococcal  type  may  penetrate  deep  into 
the  pericementum  without  producing  an  apparent  lesion.  In  view  of 
this  fact,  it  is  possible  to  conceive  that  all  pericemental  abscesses  may 
arise  as  the  result  of  invasion  of  infectious  organisms  from  the  gingival 
crevice  when  the  resistance  of  the  peridental  tissues  against  them  is  of  a 
low  order."* 

The  lesions  formed  by  pericemental  abscesses  may  be  extensive, 
involving  a  considerable  portion  of  the  peridental  membrane.  The 
prognosis  of  these  affections  is  extremely  unfavorable  especially  in 
individuals  who  are  suffering  from  constitutional  or  nutritional  dis- 
turbances. In  the  favorable  case,  if  the  root  be  freed  of  calculi  and 
carefully  planed,  slow  healing  may  take  place.     The  author  has  in 

1  International  Dental  Journal,  1894,  p.  1. 

2  Dental  Cosmos,  1900,  p.  1149. 

'  Collins  and  Lyle,  in  the  Journal  National  Dental  Association,  April,  1919,  p.  370, 
state  that  they  have  found  abundant  evidence  that  periapical  infection  may  arise  from  an 
extension  of  infected  organisms  from  diseased  gingival  tissues. 

■*  Roys  claims  that  every  case  of  pericemental  abscess  has  a  twisting,  serpigenous  tract 
by  which  it  communicates  with  the  gingival  crevice  and  that  it  is  along  this  tract  that 
the  infection  enters  the  deep  pericemental  tissues. — Dental  Cosmos,  1918,  p.  659, 


VINCENT'S  ANGINA 


575 


mind  a  case  of  pericemental  abscess  situated  at  the  bifurcation  of  the 
roots  of  a  lower  first  molar,  in  which  healing  was  successfully  accom- 
plished in  this  manner  and  the  bone  which  was  involved  largely  regen- 
erated as  was  showTii  by  roentgenograms  taken  one  year  apart  (Figs.  452 
and  453) .  But  many  cases  are  presented  which  do  not  respond  to  the 
most  careful  operative  technic  and  which  persist  in  a  state  of  active 
infection  and  suppuration  as  long  as  the  tooth  remains  in  position. 
For  them  the  only  remedy  is  extraction. 


Fig.  452. — Rueutjienofirumof  perice- 
mentai  abscess  at  bifurcation  of  roots  of 
lower  molar,  showing  destruction  of 
alveolar  bone. 


Fig.  453. — Roentgenogram  of  case 
shown  in  Fig.  452,  one  year  after  treat- 
ment by  curettage,  showing  bone  regen- 
eration.    Lesion  healed. 


VINCENT'S  ANGINA. 

Certain  ulcerative  affections  of  the  oral  tissues  frequently  may  be 
confused  with,  and  often  erroneously  diagnosed  as,  pyorrhea.  Of  these 
perhaps  the  most  common  t}^e  is  a  spreading  diphtheria-like  lesion 
which  usually  begins  in  the  pharjoix  from  which  it  spreads  to  the  oral 
tissues.  The  specific  organisms  of  this  affection  were  identified  by  W.  D . 
Miller  in  1883  as  the  fusiform  bacillus  and  an  accompanying  spirochete. 
Later  Vincent  more  fully  described  the  disease  since  which  time  it  has 
been  known  as  Vincent's  Angina.  He  classified  the  lesions  as  belonging 
to  two  groups  as  follows: 

A.  "The  superficial,  pseudo-membraneous  or  diphtheroid  form  in 
which  a  thin  grayish  white  film  usually  starts  over  one  tonsil  and 
gradually  spreads,  often  over  a  wdde  area.  Usually  the  membrane  is 
easily  removed,  though  not  en  masse,  leaving  a  red  bleeding  base  and  a 
shallow  ulceration.  There  is  generally  an  associated  diffused  pharyn- 
gitis. 

B.  "The  ulcerative,  and  more  common  form,  in  which  there  is  deep 
tissue  necrosis,  covered  by  a  thick,  creamy,  yellowish  or  gray  exudate, 
which  comes  away  easily  and  again  leaves  a  raw,  granular,  bleeding 
base.  This  leads  to  the  formation  of  crater-like  ulcers  mth  irregular, 
somewhat  indurated  and  undermined  edges." 


576  PYORRHEA  ALVEOLARIS 

This  description'  is  fairly  comprehensive  with  the  exception  that  the 
ulceration  is  not  confined  to  the  pharynx  but  rather  does  it  frequently 
spread  to  the  tissues  of  the  oral  cavity  on  which  it  produces  its  charac- 
teristic lesions.  Diuing  the  late  war  it  occurred  as  an  epidemic  among 
the  troops  in  a  highly  infective  and  contagious  form,  spreading  through- 
out the  camps  and  hospitals  with  great  rapidity.  Here  it  was  known 
as  "trench  mouth"  or  "trench  gunis."^ 

Vincent's  angina  usually  begins  with  a  sore-throat  and  a  diffused 
pharyngitis  following  which  a  thin  white  membrane  spreads  over  the 
surface  of  the  fauces  which  may  or  may  not  be  accompanied  by  definite 
ulcerative  lesions  of  the  pharyngeal  tissues.  From  this  region  the  white 
film  is  extended  toward  the  oral  cavity  which  it  encompasses  by  spread- 
ing along  the  buccal  gums  and  gingival  areas  toward  the  anterior  part 
of  the  mouth.  In  various  locations  ulcers  may  occm*  which  form  a 
creamy  exudate,  upon  the  removal  of  which  a  raw  bleeding  surface  is 
revealed.  These  affections  light  up  rapidly  and  exhibit  a  high  degree 
of  bacterial  overgrowth  so  that  within  a  few  days  all  the  tissues  of  the 
mouth  may  be  involved  by  the  inflammatory  and  ulcerative  process. 
It  is  noted,  however,  that  the  patient  is  never  as  ill  as  the  condition 
of  the  mouth  might  seem  to  warrant.  Seldom  does  the  temperature 
rise  over  101°  but  in  severe  cases  the  patient  suffers  from  extreme 
depression,  pain  in  joints  and  loss  of  appetite.  The  author  observed 
one  case,  that  of  a  soldier,  who  refused  to  eat  for  two  weeks.  As  the 
result  of  his  fasting,  combined  with  the  severe  Vincent  infection,  the 
patient  became  extremely  emaciated  and  was  for  sometime  in  a  very 
precarious  condition. 

In  the  mouth  Vincent's  angina  may  be  recognized  by  a  general 
inflammation  of  all  the  oral  mucous  membranes,  accompanied  by  a 
characteristic  white,  pseudo-membrane  on  the  gum  tissues  and  deep 
ulcerations  filled  with  white  creamy  exudate.  The  bacteriologic  find- 
ings of  material  taken  from  the  lesions  reveal  a  mixed  culture  of 
organisms  in  which  the  fusiform  bacillus  and  its  accompanying  spiro- 
chete greatly  predominate  (Fig.  454).  Two  forms  of  the  B.  fusiformis 
have  been  described,  one  a  Gram-negative  organism  which  has  flagellse 
and  is  motile,  the  other  Gram-positive  and  non-motile,  having  a  tendency 
to  clump.2  The  bacilli  appear  thickened  in  the  middle  and  pointed  at 
both  ends.  They  are  always  associated  with  a  large  spirochete  with 
which  they  live  in  symbiotic  relationship.  These  fusiform-spirochete 
cultures  are  anaerobic  in  type  under  which  conditions  they  have  been 
isolated  and  grown  on  artificial  media.  On  the  tissues  they  are  associ- 
ated with  extensive  ulcerations,  but  show  no  tendency  to  infiltration 

1  Barker  and  Miller:  Jour.  Am.  Med.  Assn.,  September  7,  1918. 

2  Hartzell:  Journal  National  Dental  Association,  1917,  p.  477. 


VINCENTS  ANGINA 


577 


or  metastasis.  The  relationship  of  these  two  organisms  to  Vincent's 
angina  is  not  clear.  Although  they  are  always  present  in  its  lesions 
and  disappear  as  they  are  healed,  artificial  production  of  the  disease 
by  inoculation  of  fusiform  bacillus  and  spirochete  cultures  has  never 
been  accomplished.  Moreover  these  organisms  are  frequent  inhabi- 
tants of  healthy  mouths  in  which  no  evidence  of  Vincent's  disease  is 
apparent.  This  is  especially  true  when  the  oral  hygiene  is  poor  and 
fermentations  are  high.  But  although  accurate  proof  of  the  specificity 
of  these  organisms  has  not  been  forthcoming,  the  consensus  of  opinion 
today  is  in  support  of  the  view  that  the  fusiform  bacillus  and  its  accom- 
panying spirochete  are  at  least  essential  factors  in  the  production  of 
Vincent's  disease. 


Fig.  454. — Fusiform  bacillus  and  spirochete  from  case  of  Vincent's  angina. i 

Although  these  conditions  are  severe  in  their  course  and  present 
clinical  pictures  which  are  startling  and  alarming,  they  usually  may  be 
controlled  and  promptly  arrested  by  the  employment  of  relatively 
simple  remedial  agencies.  In  the  great  majority  of  cases  the  mouth 
hygiene  has  been  faulty  and  quantities  of  food  and  other  deposits  are 
lodged  about  the  teeth  in  which  the  infectious  organisms  are  thriving 
in  a  high  state  of  virulence.  By  simple  prophylactic  measures  alone 
the  infective  process  may  be  greatly  reduced  and  many  times  it  may 
be  completely  eradicated  in  this  manner,  no  other  treatment  being 
necessary.  To  be  effective,  however,  these  prophylactic  measm-es 
must  be  completely  and  carefully  executed.    All  foreign  matter  must 


1  Simon  in  Adami  and  McCrae's  Text-book  of  Pathology. 


37 


578  PYORRHEA  ALVEOLARIS 

be  removed  from  about  the  teeth  and  the  gingival  crevices.  Special 
attention  should  be  given  to  those  localities  which,  by  mechanical 
retention,  offer  breeding  places  for  the  Vincent  organisms.  In  pyor- 
rheal  pockets  and  beneath  the  gum  flap  about  partially  erupted  third 
molars,  the  organism  may  be  retained  to  reinfect  the  mouth  and  bring 
on  a  recurrence  of  oral  infection  unless  special  attention  is  given  to 
these  areas.  In  addition  to  prophylactic  measures  a  variety  of  thera- 
peutic agents  have  been  suggested  for  the  control  of  the  infection. 
Local  applications  of  iodin,  silver  nitrate  (10  per  cent.),  chromic  acid 
(5  per  cent.),  zinc  sulphate,  hydrogen  peroxid,  wine  of  ipecac.  Fowler's 
solution,  salvarsan  and  arsphenamin,  are  recommended  by  various 
authorities  as  well  as  the  systemic  administration  of  arsphenamin  and 
fusiform-spirochete  inoculations.  All  writers  agree  that  mercury  in  all 
forms  is  contra-indicated  in  these  conditions  as  the  drug  tends  to  in- 
crease the  virulence  of  Vincent's  angina  and  actively  interferes  with 
its  control. 

The  following  method  has  been  used  successfully  by  the  author  in  a 
large  number  of  cases : 

Swab  the  mucous  membrane  of  the  mouth  and  pharynx  with  cotton 
saturated  with  H2O2,  in  this  manner  mechanically  remove  the  white 
pseudo-membrane. 

Superficial  oral  prophylaxis,  care  being  taken  not  to  injure  the  soft 
tissues. 

Cleanse  ulcerative  lesions  and  remove  slough  with  cotton  swab 
saturated  with  silver  nitrate  (10  per  cent.),  or  argyrol  (25  per  cent.). 

Swab  the  mouth  with  iodin  lotion  (p.  161). 

Instruct  the  patient  to  rinse  the  mouth  every  three  hours  with 
hydrogen  peroxide  (1  per  cent.)  followed  by  potassium  permanganate 
0.5  per  cent,  and  swab  mucous  membrane  with  cotton  to  remove  the 
infective  film. 

If  the  lips  are  cracked  and  peeling  they  may  be  painted  with  tincture 
of  iodin. 

At  subsequent  sittings  the  oral  prophylaxis  should  be  completed  as 
soon  as  the  condition  of  the  soft  tissues  will  allow.  Swab  with  iodin 
lotion. 

These  measures  should  be  continued  until  all  evidences  of  inflamma- 
tion have  disappeared. 

Finally,  all  residual  nests  of  organisms  should  be  eradicated. 
Diseased  tonsils  and  impacted  or  partially  erupted  third  molars  are 
favorite  breeding  grounds,  which  frequently  must  be  removed  to  per- 
manently control  the  infection. 

In  a  great  majority  of  the  cases  a  careful  performance  of  these 
measures  will  result  in  the  immediate  improvement  of  the  diseased 


RETRACTION  OF   THE   GUMS 


579 


tissues  and  a  rapid  return  to  health,  complete  recovery  even  of 
severe  cases  frequently  occurring  in  a  few  days  or  a  week  (Fig.  455). 
When  the  infection  still  persists  for  some  time  after  treatment,  or 
periodically  recurs  after  a  temporary  abatement,  it  is  very  probable 
that  either  the  prophylactic  measures  have  been  incompletely  per- 
formed or  some  hidden  breeding  ground  exists  from  which  the  mouth  is 
continually  being  reinfected.  When  Vincent's  disease  is  associated 
with  pyorrhea  the  treatment  is  not  so  simple  a  matter  and  complete 
eradication  of  the  specific  organism  cannot  be  accomplished  without 
concurrent  treatment  and  obliteration  of  the  pyorrheal  lesions. 


Fig.  455. — Before  and  after  treatment  of  a  case  of  severe  Vincent's  angina. 

taken  six  weeks  apart. 


Pictures 


RETRACTION  OF  THE  GUMS. 

In  this  connection  we  should  consider  certain  conditions  which 
result  in  the  shrinkage  and  retraction  of  the  gum  tissues  about  the 
teeth  and  which  are  often  erroneously  considered  as  pyorrhea  alveo- 
laris.  It  is  a  matter  of  common  observation  that  the  gingival  margins 
about  the  teeth  may  be  retracted  exposing  more  or  less  of  their  roots 
without  the  formation  of  subgingival  pockets.  The  process  is  essen- 
tially that  of  a  deflection  of  the  gingivae,  apically,  along  the  roots  of  the 
teeth,  the  remaining  peridental  tissues  appearing  quite  like  the  normal. 
This  retraction  of  the  gum  may  take  place  about  one  tooth,  or  may 
occur  about  several  or  all  of  the  teeth  in  the  mouth.  These  changes 
in  the  gingival  contour  are  not  due  solely  to  shrinkage  of  the  gum 
tissues,  but  are  associated  with  degenerative  changes  in  the  alveolar 
crest  of  bone  by  which  the  bone  is  reduced  in  size  and  the  overhing 
gum  tissue  and  gingivae  sink  down  with  it  exposing  the  cementum  of  the 
root  to  which  the  free  border  of  the  gum  is  firmly  attached.  Since  no 
subgingival  pockets  are  formed  these  lesions  are  not  pyorrheal  in  t^-pe 
and  should  not  be  confused  with  that  condition.  They  occur  in 
several  different  forms  which  may  be  grouped  as  follows: 


580 


PYORRHEA  ALVEOLARIS 


Senile  Atrophy. — In  individuals  past  middle  age  the  gum  margins 
frequently  are  retracted  from  the  normal  positions  on  the  tooth  and  a 
portion  of  the  cementum  is  exposed.  In  these  cases  the  crest  of  alveolar 
bone  has  undergone  senile  atrophy,  and  as  a  result,  the  gums  and 
gingivse  on  all  sides  of  the  teeth  gradually  settle  down  to  lower  and 
lower  levels  about  the  roots.  A  very  similar  condition  may  arise  in 
earlier  years  from  a  premature  or  precocious  senility  of  the  individual. 
If  the  mouth  and  teeth  are  kept  clean  and  free  from  irritating  agents 
senile  degeneration  of  the  peridental  tissue  takes  place  slowly  and  is 
of  little  significance  other  than  that  it  may  be  followed  by  sensitivity 
of  the  root  surfaces  and  an  unsightly  appearance  of  the  teeth. 

Traumatism. — ^A  similar  retraction  of  the  gum  tissues  on  the  buccal 
and  labial  surfaces  of  the  teeth  frequently  occurs  as  the  result  of 
excessive  and  improper  tooth-brushing.    When  the  teeth  are  brushed 


Fig.  456. — Severe  labial  recession  from  tooth  brush  abrasion. 


vigorously  in  a  cross-wise  manner  undue  stress  is  placed  upon  the 
gingivae  with  the  result  that  degenerations  may  take  place  in  the  under- 
lying tissues  and  the  gingival  border  is  retracted.  These  lesions  occur 
at  the  site  of  the  irritation  and  are  usually  associated  with  a  lesion 
in  the  enamel  of  the  tooth  due  to  tooth  brush  abrasion  (Fig.  456) . 

Triaumatic  retraction  of  the  gum  tissues  about  the  teeth  may  be 
produced  also  by  the  encroachment  of  calculi  on  the  gingivse  by 
operative  procedures,  crowns,  fillings,  etc.,  and  by  the  abnormal 
excursions  of  food  in  mastication.  Examples  of  the  latter  are  seen  in 
cases  in  which  the  normal  proximate  contact  of  the  teeth  is  lost  by 
reason  of  which  food  is  habitually  crowded  between  them  in  mastication 
and  the  interproximate  gum  tissues  are  severely  injured  (Fig.  106). 
So  also  in  those  cases  in  which  the  teeth  do  not  have  a  proper  buccal 
or  lingual  contour  the  gingivse  may  be  accidentally  torn  in  the  act  of 
biting  some  hard  substance  and  future  irritations  of  food  may  continue 


RETRACTION  OF  THE   GUMS 


581 


the  retraction  for  a  considerable  distance  down  the  side  of  the  root 
(p.  167).  If  the  oral  hygiene  be  poor,  these  forms  of  traumatic  gum 
retraction  may  develop  into  true  pyorrheal  lesions  at  the  site  of  injury 
and  they  should  always  be  considered  as  factors  predisposing  to  that 
disease  (Fig.  457).     In  the  case  of  tooth-brush  abrasion,  a  correction 


Fig.  457. — -Severe  labial  recession  on  lower  right  cuspid  from  the  traumata  of  food  and 

pyorrheal  involvement. 

of  the  manner  of  brushing  the  teeth  will  usually  suffice  to  prevent 
further  recession  of  the  gum.  Retractions  from  the  traumatism  of 
calculi  and  irritations  of  food,  fillings,  etc.,  may  be  arrested  in  their 
progress  by  a  careful  and  complete  removal  of  the  irritant  or  a  correc- 
tion of  faulty  tooth  contours,  but  the  lesion  which  has  already  been 


Fig.  458. — Before  and  after  treatment  of  case  of  Vincent's  angina  showing  regeneration 
of  interproximate  gum  tissues  in  bicuspid  region.    Two  pictures  six  months  apart. 

accomplished  usually  remains  as  a  permanent  defect.  In  acute  cases 
in  which  the  alveolar  bone  is  not  seriously  affected,  a  removal  of  the 
irritant  may  result  in  a  regeneration  of  the  interproximate  gum  tissues, 
but  rarely  are  they  replaced  on  the  buccal  or  lingual  surfaces  of  the 
teeth. 


582  ,         PYORRHEA  ALVEOLARIS 

Ulcerative  Gingivitis. — Occasionally  a  rapidly  growing  superficial 
type  of  infection  may  produce  an  ulceration  of  the  free  margins  of  the 
gums  by  which  they  are  eroded  and  retracted.  The  fusiform  bacillus 
in  Vincent's  angina  frequently  produces  lesions  of  this  type.  The 
interproximate  tissues  suffer  most  severely,  becoming  inverted  while 
the  labial  and  lingual  borders  are  retracted  to  expose  the  cementum. 
By  careful  prophylactic  measures  and  the  establishment  of  oral  hygiene 
these  ulcerations  may  be  promptly  arrested  and  if  they  have  not 
progressed  far  enough  to  seriously  affect  the  alveolar  bone  the  eroded 
gum  tissues  usually  will  be  regenerated  and  restored  to  their  normal 
form  (Fig.  458). 

Healed  Lesions  of  Pyorrhea. — ^Following  the  successful  treatment  of 
pyorrhea  it  will  be  found  that,  as  a  rule,  the  gum  tissues  have  shrunken 
about  the  teeth.  This  is  due  to  the  fact  that  in  the  removal  of  the 
peridental  irritations  the  gingival  circulation  is  stimulated,  congestion 
and  inflammatory  derangements  are  abated,  and  the  swollen  tissues 
shrink  to  their  normal  thickness.  Since  in  the  process  of  the  disease, 
the  underlying  bone  tissues  have  degenerated  and  decreased  in  size 
the  overlying  gum  tissues  which  cover  them  will  consequently  fall  away 
from  the  neck  of  the  teeth  and  attach  themselves  to  the  roots  at  a  line 
farther  apically  than  is  normal.  It  follows,  therefore,  that  in  all  cases 
of  severe  pyorrhea,  when  as  the  result  of  successful  treatment  the 
peridental  tissues  have  become  attached  to  the  roots  and  the  subgingival 
pockets  obliterated,  a  new  gingival  line  will  be  formed  which  will  be 
retracted  from  the  normal  position  (Figs.  435 ,  437, 447  and  448) .  These 
post-pyorrheal  gum  retractions  if  properly  cared  for  and  kept  free  from 
excessive  irritations  form  permanent  attachments  to  the  cementum  and 
constitute  the  most  effectual  approach  to  healing  of  pyorrheal  lesions. 


CHAPTER  XIV. 

EXTRACTION  OF  TEETH  AND  OTHER  SURGICAL 
PROCEDURES. 

By  CHALMERS  J.  LYONS,  D.D.Sc. 

Surgical  Anatomy. — To  extract  teeth  successfully,  the  operator  should 
be  m  possession  of  a  thorough  knowledge  of  the  anatomy  of  the  teeth 
and  surrounding  parts  m  order  that  the  forces  in  the  line  of  least 
resistance  may  be  applied  intelligently.  The  relation  of  the  teeth  to 
the  maxillary  sinus,  the  character  of  the  bone,  the  importance  of  the 
canine  eminence,  the  canine  fossa,  and  the  surfaces  of  the  bone  in  the 
upper  jaw,  as  well  as  the  relation  of  the  teeth  to  the  inferior  dental 
canal,  the  positions  of  the  mental  and  mandibular  foramina,  together 
with  the  study  of  the  character  of  bone  and  the  relation  of  the  teeth  to 
the  coronoid  process  in  the  lower  jaw,  are  all  matters  which  will  be 
great  aids  in  the  success  of  the  operation  of  extraction  of  teeth. 

The  Relation  of  the  Teeth  to  the  Maxillary  Sinus. — "Because  of  the 
close  anatomical  relation  of  the  maxillary  sinus  with  the  tooth  germs 
and  the  roots  of  the  permanent  teeth,  it  is  evident  that  the  sinus  must 
be  more  or  less  influenced  by  them.  As  the  teeth  develop  and  descend 
into  their  normal  position,  the  sinus  increases  in  size.  If  a  tooth  situ- 
ated near  the  sinus  be  retarded  in  its  eruption,  the  development  of  the 
sinus  is  interfered  with  at  that  particular  point. "^  Fig.  459  shows  how 
closely  the  apices  of  the  teeth  may  be  associated  with  the  maxillary 
sinus.  Particularly  is  this  true  with  the  first  and  second  bicuspids  and 
first  molars.  In  rare  cases  the  apical  end  of  the  root  of  the  cuspid  and 
the  second  and  even  the  third  molar  may  encroach  upon  the  antral 
cavity.  Infection  about  the  roots  of  these  teeth  may,  and  frequently 
does,  give  rise  to  morbid  conditions  in  the  maxillary  sinus. 

In  the  extraction  of  the  upper  first  molar,  care  should  be  exercised 
that  a  portion  of  the  floor  of  the  antrum  is  not  fractured  away  during 
the  operation.  The  roots  of  this  tooth  passing  up  on  both  sides  of  the 
antral  cavity  predispose  to  such  an  accident.  In  the  extraction  of  the 
roots  of  the  upper  bicuspids  the  same  care  should  be  exercised  that 
they  are  not  forced  through  the  floor  of  the  maxillary  sinus  in  the 
endeavor  to  engage  them  in  the  forceps. 

1  Cryer:  Internal  Anatomj-  of  the  Face. 

(583) 


584     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

Character  of  the  Bone  of  the  Maxillse. — ^The  alveolar  process  of  both 
upper  and  lower  jaws  consists  of  an  outer  and  inner  plate  of  dense 
cortical  bone.  Between  these  two  plates  are  the  sockets  for  the  roots 
of  the  teeth.  The  sockets  are  surrounded  by  a  very  thin  layer  of 
cortical  bone,  and  the  remaining  portion  of  the  alveolar  process  between 
the  outer  and  inner  plates  is  filled  in  with  cancellated  or  spongy  bone. 
Running  through  this  cancellated  or  spongy  bone  are  fine  canals  for 
nerves  and  bloodvessels,  the  remaining  portion  of  it  being  connective 
tissues.  The  surfaces  of  the  outer  and  inner  plates  have  no  definite 
line  of  demarcation  between  the  maxillse  proper  and  the  alveolar 


Ostium 
maxillare 


First  molar 

Fig.  459. 


First  molar 


-(Cryer.) 


process,  but  continue  from  the  cervical  margin  over  on  the  maxillse 
and  are  lost  on  the  outer  and  inner  surfaces  of  these  bones.  The 
alveolar  process  is  covered  with  muco-periosteum,  which  is  thick  and 
dense  and  contains  mucous  glands.  This  covering  is  commonly  known 
as  gum  tissue.  The  bone  proper  is  covered  with  true  periosteum.  Fig. 
460  shows  the  anterior  view  of  a  normally  articulated  skull.  It  may 
be  seen  that  the  central  incisors  are  in  close  proximity  to  the  suture 
which  unites  the  right  and  left  maxillse.  This  is  important  knowledge 
for  the  operator  when  extracting  under  local  anesthesia.  (See  Chapter 
XII.)  The  outer  plate  covering  the  lateral  incisors  is  very  heavy 
because  the  labio-lingual  diameter  of  the  lateral  incisors  is  less  than 


CANINE  EMINENCE 


585 


that  of  the  teeth  on  either  side.  T]ie  outer  i)late  of  the  ah^eolar  i^rocess 
is  deflected  from  the  cuspid  tooth  over  on  the  central  incisor  tooth.  A 
depression  results  from  this  deflection  and  forms  the  incisive  fossa. 


Fig.  460. — Anterior  view  of  the  typical  skull.     (Cryer.) 


The  Canine  Eminence. — In  viewing  the  anterior  surface  of  the  skull 
we  may  observe  a  heavy  bony  structure  extending  over  the  cuspid 
teeth  (the  canine  eminence).    This  varies  in  thickness  in  individuals 


586     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

and  must  be  taken  into  consideration  in  the  extraction  of  the  cuspid 
teeth. 

The  Canine  Fossa. — ^The  canine  fossa  marks  the  thinnest  part  of  the 
outer  plate  of  the  superior  maxilla  and  forms  the  outer  wall  to  the 
maxillary  sinus.  This  plate  is  extremely  thin  in  old  age  and  in  such  a 
case  great  care  should  be  exercised  in  the  extraction  of  the  bicuspids 
and  molars,  that  this  surface  be  not  injured  and  the  antral  cavity 
exposed. 

The  Infra-orbital  Foramen. — ^This  foramen,  through  which  the  infra- 
orbital nerve  emerges  on  the  face,  lies  above  the  canine  fossa.  It 
becomes  an  important  landmark  in  the  use  of  conduction  anesthesia 
for  the  extraction  of  the  anterior  teeth.     (See  Chapter  XII.) 


Fig.  461. — Zygomatic  surface  of  superior  maxilla. 


The  alveolar  process  of  the  superior  maxilla  is  less  dense  than  that 
of  the  inferior  maxilla,  which  condition  usually  renders  extraction  of 
teeth  less  difficult  than  in  the  inferior  maxilla. 

The  posterior  or  zygomatic  surface  of  the  superior  maxilla  assists 
in  the  formation  of  the  spheno-maxillary  fossa  and  presents  the  tuber- 
osity, which  is  a  rounded  prominence  above  the  third  molar  tooth 
(Fig.  461).  This  part  of  the  superior  maxilla  contains  innumerable 
fine  canals  for  the  accommodation  of  the  nerve  and  bloodvessels.  The 
tuberosity  varies  in  size  in  each  individual  and  may  vary  on  the  two 
sides  of  the  jaw  in  the  same  individual. 

Palatine  Surface. — ^The  landmarks  on  the  palatine  surface  of  the 
superior  maxilla  which  should  be  observed  in  the  extraction  of  teeth, 
are  the  foramina  of  scarpa  which  are  located  one  centimeter  distal  to 
the  central  incisor  teeth  and  the  posterior  palatine  foramina  which  are 
located  about  one  centimeter  toward  the  median  line  from  the  upper 


INFERIOR   MAXILLA 


587 


third  molar  teeth  (Fig.  462).     The  nerves  and  vessels  supplying  the 
hard  and  soft  palates  emerge  at  these  points. 


Fig.   462. — ^Anterior  portion  of  the  base  of  a  typical  skull.     (Cryer.) 


Inferior  Maxilla. — ^The  exterior  of  the  bone  and  landmarks  of  the 
inferior  maxilla  or  mandible  should  be  studied  by  the  operator.  The 
alveolar  process  of  this  bone  being  more  dense  than  that  of  the  superior 
maxilla,  extraction  of  the  teeth  will  be  more  difficult. 

Mental  Foramen.^Ahout  five  millimeters  below  the  bicuspids  and 
two  millimeters  in  front  of  the  second  bicuspid  the  mental  foramen 
may  be  found  (Fig.  463).  This  point  is  considered  the  weakest  point 
in  the  mandible  and  fractures  of  the  jaw  through  this  area  are  more 
common  than  at  any  other  point.  Posterior  to  the  mental  foramen 
the  alveolar  process  becomes  very  dense  and  heavy,  consequently 
the  lower  molars  are  usually  more  difficult  to  extract  than  any  of  the 


588     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

other  teeth.  Also,  on  account  of  the  density  of  the  alveolar  process, 
infiltration  anesthesia  for  extraction  of  teeth  in  this  region  becomes 
less  satisfactory.     (See  Chapter  XII.) 


V„^,,,|ii»i 


Fig.  463. — The  right  side  of  the  lower  portion  of  face.       (Cryer.) 


J 


Mandibular  Foramen. — On  the  inner  surfaces  of  the  mandible  on 
a  line  with  the  occluding  surfaces  of  the  teeth  and  about  half-way 
between  the  coronoid  and  condyloid  processes,  there  is  an  important 
foramen  (the  mandibular)  (Fig.  464) .  This  foramen  marks  the  entrance 
of  the  inferior  dental  nerve  and  vessels  into  the  mandible.  Arising 
from  the  body  of  the  mandible  are  two  processes,  the  one  in  front 
being  the  coronoid,  and  the  one  behind,  the  condyloid  process. 
Arrested  development  of  the  inferior  maxilla  will  result  in  the  crowd- 
ing and  impaction  of  the  teeth.  In  the  process  of  development  of  the 
mandible,  room  for  the  normal  eruption  of  the  first,  second,  and  third 
molars  is  provided  by  the  physiologic  absorption  of  the  anterior 
surface  of  the  coronoid  process.  Not  infrequently  a  pathologic  con- 
dition arises  which  interferes  with  this  process  of  development  and 
this  knowledge  is  necessary  for  the  operator  iii  determining  the  degree 
of  force  and  direction  of  the  application  of  it  in  the  extraction  of  the 
inferior  teeth. 


INDICATION  AND  CONTRA-INDICATION  FOR  EXTRACTION    589 

Indication  and  Contra-indication  for  Extraction. — ^The  conditions  which 
should  govern  the  practitioner  in  determining  the  indication  and 
contra-indication  for  the  extraction  of  teeth  are  so  varied  that  it  is  not 
practicable  to  formulate  any  hard  and  fast  rules  that  will  apply  in  all 
cases.  Not  only  the  local  conditions  but  the  general  systemic  condi- 
tions of  the  patient  must  be  considered  in  determining  whether  or  not 
the  teeth  should  be  extracted.  There  seems  to  be  quite  a  diversity  of 
opinion  at  this  time  as  to  the  exact  status  of  pulpless  teeth.  Some 
operators  go  so  far  as  to  state  that  all  pulpless  teeth  are  a  menace  to  the 
welfare  of  the  patient  and  that  such  teeth  should  be  extracted;  others 
believe  that  under  certain  conditions  pulpless  teeth  can  be  made  safe 
if  properly  treated  and  that  the  patient  will  be  able  to  retain  them 
indefinitely.     In  view  of  the  recorded  data  on  this  subject,  it  would 


Fig.   464.- — Inner  surface  of  the  inferior  maxilla.      (Cryer.) 


seem  that  in  determining  the  indication  or  contra-indication  for  the 
extraction  of  such  teeth  the  physical  condition  of  the  patient  and  the 
strategical  importance  of  the  teeth,  respectively,  should  be  the  deciding 
factors.  Some  of  the  most  important  causes  which  demand  extraction 
of  the  teeth  are  as  follows : 

1 .  INIolar  teeth  which  have  lost  their  occluding  teeth  in  the  opposite 
jaw  and  are  partially  exfoliated  from  their  alveoli  and  are  becoming  a 
source  of  annoyance.  When  such  a  condition  occurs  in  the  bicuspid 
region,  the  vacant  space  in  the  opposite  jaw  should  often  be  filled  with 
an  artificial  tooth  to  prevent  the  exfoliation  of  the  natm'al  tooth. 

2.  Multi-rooted  teeth  with  chronic  alveolar  abscesses,  when  Roent- 
genographic  evidence  shows  disease  and  death  of  the  pericemental  mem- 
brane in  the  apical  area.     In  single-rooted  teeth  this  condition  ma}^  be 


590     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

taken  care  of  by  apicoectomy/  provided  the  physical  resistance  of  the 
patient  indicates  it.  Extraction  is  indicated  in  any  single-rooted 
tooth  wherein  there  is  evidence  of  disease  or  death  of  the  pericemental 
membrane  extending  over  more  than  the  apical  third  of  the  root. 
Such  a  condition  would  preclude  the  possibility  of  saving  the  tooth  by 
apicoectomy. 

3.  Malposed  teeth  which  cannot  be  corrected  by  orthodontic 
measures  so  as  to  become  useful. 

4.  Pulpless  teeth  with  constricted  or  crooked  canals  which  will 
prevent  their  proper  treatment. 

5.  Teeth  in  which  the  pulps  are  encroached  upon  by  pulp  stones  and 
cannot  be  properly  treated. 

6.  Unerupted  teeth  which  are  apparently  lying  dormant  in  the  jaws 
or  where  they  are  causing  a  dental  cyst.  The  possibility  of  these  teeth 
giving  rise  to  morbid  conditions  always  makes  their  removal  desirable. 

7.  Lower  third  molars  which  are  partially  erupted  and  are  causing 
the  surrounding  tissues  to  be  impinged  upon  by  the  occluding  teeth, 
so  that  inflammation  results  periodically. 

8.  A  tooth  that  is  partially  or  completely  impacted  and  is  impinging 
upon  another  tooth  may  be  the  seat  of  extreme  nervous  disturbances 
with  manifestations  remote  from  the  impacted  tooth;  an  impacted 
tooth  that  is  causing  partial  resorption  of  the  tooth  upon  which  it  is 
impinging;  and  an  impacted  tooth  that  is  the  seat  of  a  periodical 
inflammatory  process. 

9.  When  preparing  a  mouth  for  an  artificial  denture,  the  removal  of 
sound  healthy  teeth  may  be  indicated  for  the  purpose  of  making  a 
more  efficient  denture. 

10.  Teeth  which  have  become  loosened  by  any  inflammatory  process 
to  such  an  extent  that  a  considerable  portion  of  the  alveolar  process 
has  been  lost.  This  condition  may  be  applied  to  roots  that  have 
supporting  crowns  and  bridges  that  have  become  loosened  due  to  some 
pathologic  condition. 

11.  Deciduous  teeth  which  are  retained  after  the  time  of  their  normal 
exfoliation  and  are  preventing  the  eruption  of  the  permanent  teeth. 

12.  Abscessed  deciduous  teeth  which  will  not  respond  to  treatment 
and  are  a  menace  to  the  health  of  the  patient.  It  will  sometimes 
tax  the  judgment  of  the  operator  to  choose  the  right  method  of  pro- 
cedure in  these  cases.  If  the  tooth  be  extracted  before  the  normal  time 
for  the  eruption  of  the  permanent  tooth,  mal-occlusion  may  result;  if 
not  extracted,  the  patient's  health  may  be  impaired. 

13.  Supernumerary  teeth  that  are  of  no  particular  value  and  are 
interfering  with  the  normal  eruption  of  the  permanent  teeth. 

'  This  subject  is  treated  fully  at  the  end  of  the  chapter. 


CONTRA-INDICATIONS   FOR   THE  EXTRACTION  OF   TEETH     591 

Contra-indications  for  the  Extraction  of  Teeth.- — A  careful  examination 
of  the  whole  mouth  should  be  made  before  extraction  of  any  of  the 
teeth  is  begun  so  that  a  needless  sacrifice  of  tooth  function  will  not  be 
made.  The  demand  that  a  tooth  be  extracted  should  not  be  taken  into 
consideration,  because  a  patient's  knowledge  of  mouth  conditions  is 
necessarily  limited,  and  the  patient  is  not  capable  of  judging  the  value 
of  the  tooth  in  question.  The  operator's  judgment  should  always 
prevail.  ]\Iany  times  a  small  cavity  in  an  otherwise  perfectly  normal 
tooth  may  be  causing  the  patient  considerable  pain,  and  the  patient, 
not  placing  the  proper  importance  on  the  tooth,  may  request  its 
removal.  It  should  be  considered  bad  practice  to  accede  to  the 
patient's  wishes  in  these  matters  unless  by  so  doing  the  patient's  future 
welfare  will  be  better  taken  care  of.  The  operator  should  decline  to 
remove  a  tooth  that  is  of  any  value  to  the  patient.  The  patient's 
futiue  welfare  must  always  be  uppermost  in  the  operator's  mind  when 
determining  the  indications  and  contra-indications  for  the  extraction 
of  teeth.  Some  of  the  most  important  contra-indications  for  the 
extraction  of  teeth  are  as  follows : 

1.  Often  when  preparing  a  mouth  for  an  upper  or  lower  denture, 
certain  teeth,  such  as  upper  or  lower  cuspids  that  are  in  good  alignment, 
will  help  to  retain  the  artificial  denture  and  should  not  be  extracted. 

2.  With  patients  of  advanced  age  who  have  lost  bicuspids  and 
molars,  where  there  has  been  marked  resorption  of  the  alveolar  pro- 
cesses and  the  remaining  teeth  are  worn  down  by  mechanical  abrasion, 
it  is  sometimes  a  debatable  question  whether  the  patient's  welfare  ^dll 
be  better  taken  care  of  by  extraction,  or  by  leaving  the  teeth  in  the 
mouth  and  depending  upon  the  abraded  surfaces  for  mastication. 
In  such  cases,  artificial  dentures  are  not  usually  very  satisfactory. 

3.  The  extraction  of  a  tooth  is  contra-indicated  in  patients  who  have 
organic  heart  lesions  such  as  valvular  insufficiency,  hj^Dertrophy,  and 
fatty  degeneration.  The  shock  from  extractions  in  such  cases  may 
result  fatally  to  the  patient.  When  it  is  necessary  to  extract  teeth 
under  such  conditions,  the  patient's  physician  should  be  present. 

4.  In  cases  of  abscessed  teeth,  which  are  to  be  extracted  when  the 
operator  is  assured  that  the  abscess  can  be  evacuated  by  the  removal 
of  the  tooth,  extraction  is  always  a  safe  procedure.  But  in  certain 
other  cases  of  acute  alveolar  abscess  where  there  is  extreme  cellulitis 
and  the  patient  is  suffering  from  septic  intoxication,  when  the  proba- 
bilities are  that  the  extraction  of  a  tooth  will  not  evacuate  the 
abscess,  and  the  possibilities  are  that  the  extraction  of  a  tooth  will 
turn  septic  intoxication  into  septicemia,  extraction  is  contra-indicated. 
In  these  cases  palliative  treatment  should  be  instigated  and  continued 
until  normal  conditions  are  reestablished. 


592     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

5.  Often  in  partially  unerupted  third  molars  the  gum  tissue  over- 
lying the  occluding  surface  of  the  third  molar  will  become  bruised  as  a 
result  of  mastication,  and  an  irritation  will  be  set  up  which  will  later 
cause  an  inflammatory  process  followed  by  trismus.  It  is  good  prac- 
tice to  treat  the  condition  and  allay  the  inflammatory  process  before 
extracting  the  tooth. 

6.  When  a  patient  with  a  history  of  profound  bleeding  presents  for 
extraction,  great  care  should  be  exercised  against  extracting  too  many 
teeth  at  one  time.  Whenever  possible  a  general  treatment  should  be 
instituted.  The  administration  of  calcium  lactate  in  ten-grain  doses, 
three  times  per  day  for  three  or  four  weeks  preceding  the  operation  will 
sometimes  yield  good  results.  These  patients  should  be  put  under 
the  care  of  a  physician  before  extraction  of  the  teeth. 

7.  In  all  cases  of  pregnancy  the  operation  should  be  postponed,  if 
possible.  In  cases  when  it  is  necessary  to  remove  one  or  more  teeth 
for  the  comfort  of  the  patient,  it  should  be  done  under  the  order,  and 
if  possible,  in  the  presence  of  the  family  physician. 

8.  The  shock  of  extraction  of  teeth  for  epileptics  may  bring  on  an 
attack.  When  it  is  necessary  to  extract  teeth  for  these  patients, 
they  should  be  watched  following  the  operation.  Should  an  attack 
follow,  the  patient  should  be  laid  in  a  comfortable  position  with 
plenty  of  fresh  air,  and  the  condition  should  not  be  considered 
alarming. 

Other  conditions  may  arise  where  the  judgment  of  the  operator  may 
be  taxed  to  the  utmost  in  order  to  determine  the  right  course  to  pursue. 
The  present  general  health  of  the  patient,  the  resistance  of  the  patient 
to  disease,  the  question  of  the  patient's  future  welfare  following 
the  sacrifice  of  a  tooth  are  all  factors  that  must  govern  the  operator  in 
determining  the  operative  procedure.  The  operator  should  endeavor 
to  make  a  judicious  diagnosis  in  every  case.  In  many  cases  a  complete 
physical  diagnosis  by  a  physician  may  be  necessary  to  complete  the 
chain  of  factors  which  must  be  considered  in  determining  the  indications 
and  contra-indications  for  the  extraction  of  certain  teeth. 

Management  of  the  Patient  During  the  Extraction  of  Teeth,^ — There 
is  probably  no  minor  operation  in  surgery  that  the  average  patient 
looks  upon  with  so  much  fear  and  dread  as  that  of  the  extraction  of  a 
tooth.  The  patient  comes  into  the  office  in  a  nervous  condition,  and 
the  first  duty  of  the  operator  is  to  get  the  patient's  mind  in  a  con- 
dition for  the  operation.  With  young  children  it  is  bad  practice  to 
promise  a  painless  operation  when  the  operator  knows  that  he  cannot 
do  it.  These  children  will  be  the  future  patients,  and  once  their 
confidence  in  the  dentist  is  lost,  it  is  sometimes  hard  to  regain.  The 
operator  should  never  manifest  nervousness  before  his  patient.     If  the 


EXTRACTION  OF  INDIVIDUAL   TEETH  593 

operator  feels  absolute  confidence  in  his  own  ability,  this  will  be 
imparted  to  the  patient. 

Position  of  Patient. — ^The  patient  should  be  made  as  comfortable  in 
the  chair  as  possible,  and  should  then  be  placed  in  a  position  with  the 
principal  object  of  securing  a  good  view  of  the  affected  tooth  and  the 
surrounding  parts.  The  position  of  the  patient  and  operator  will 
vary  slightly  for  the  extraction  of  each  tooth.  The  tooth  to  be  operated 
upon  should  be  in  full  view  of  the  operator,  and  the  head  of  the  patient 
in  such  a  position  that  it  can  be  steadied  and  controlled  by  the  left  arm 
and  hand  of  the  operator.  The  modern  dental  chair  is  the  best  appara- 
tus obtainable  upon  which  the  operation  can  be  made.  At  times  it 
may  be  necessary  to  extract  teeth  while  the  patient  is  in  bed  or  on  an 
operating  table.  In  such  cases,  the  position  of  the  patient  may  not 
always  be  the  most  desirable  one,  and  the  operator  will  have  to  adjust 
his  position  to  meet  the  requirements.  When  operating  on  a  table, 
the  best  position  for  the  operator  is  at  the  head  and  a  little  to  the  right 
side.  The  position  of  the  patient  and  operator  will  be  taken  up  in 
detail  in  the  description  of  extracting  individual  teeth. 

Extraction  of  Individual  Teeth. — ^We  will  first  consider  extraction  of  the 
superior  teeth.  As  a  rule,  this  operation  is  not  so  difficult  as  the 
extraction  of  the  inferior  teeth,  for  the  reason  that  the  superior  teeth 
are  more  accessible  and  the  alveolar  process  is  not  so  dense.  The 
forceps  are  the  principal  instruments  used  in  the  extraction  of  superior 
teeth.  Occasionally  chisels,  elevators  and  drills  may  be  used  to 
advantage  in  the  removal  of  roots  and  unerupted  and  impacted  teeth. 

The  position  of  the  operator  when  operating  on  the  superior  teeth 
is  to  the  side  and  slightly  to  the  front  of  the  patient's  head  when 
extracting  on  the  right  side,  and  a  little  in  front  of  this  position  when 
extracting  those  on  the  left  side.  The  order  of  extraction  may  be  made 
a  matter  of  preference  with  the  operator.  Usually  the  field  of  opera- 
tion can  be  kept  in  sight  better  if  he  proceeds  from  the  anterior  to  the 
posterior,  first  on  the  left,  then  on  the  right  side.  The  position  of  the 
patient  for  operating  on  the  superior  teeth  should  be  erect  and  the 
patient  raised  in  the  chair  to  such  a  height  that  the  patient's  head  comes 
just  below  the  shoulder  of  the  operator  after  the  chair  has  been  tilted 
slightly  back.  The  head  may  be  turned  from  one  side  to  the  other  as 
conditions  will  require.  Usually  all  of  the  teeth  can  be  extracted 
without  changing  the  adjustment  of  the  chair  after  it  is  once  made. 

Extraction  of  Superior  Central  Incisor. — ^Fig.  465  shows  position  of 
operator  and  patient  for  the  removal  of  superior  central  incisors. 
The  left  arm  of  the  operator  is  placed  upon  the  head  of  the  patient 
with  the  palm  of  the  hand  over  the  left  cheek.  The  upper  lip  is  raised 
to  show  the  field  of  operation  with  the  index  finger.  The  second  finger 
38 


594     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

is  used  as  a  retractor  for  the  purpose  of  retracting  the  cheek.  The 
palm  of  the  hand  and  remaining  fingers  support  the  jaws.  This 
position  of  the  hand  and  arm  enables  the  operator  to  hold  the  patient's 
head  securely  during  the  operation.  The  forceps  usually  employed  in 
the  extraction  of  superior  incisors  are  those  shown  in  Fig.  479.  The 
forceps  are  adjusted  to  the  labial  and  lingual  surfaces  of  the  central 
incisor  and  forced  upward  under  the  free  margin  of  the  gum  to  the 
edge  of  the  alveolar  process.    The  handles  of  the  forceps  are  then 


Fig.  465 


gripped  firmly  and  by  the  force  of  rotation  slightly  to  the  left,  then  to 
the  right,  the  tooth  is  loosened  from  its  attachment  and  by  a  slight 
force  of  traction  the  tooth  is  lifted  from  the  socket.  The  forceps 
should  be  adjusted  in  a  direct  line  with  the  long  axis  of  the  tooth.  If 
this  is  not  done,  fracture  of  the  tooth  may  result. 

Extraction  of  Superior  Lateral  Incisor. — ^This  tooth  is  much  smaller 
than  the  central.  Its  root  is  somewhat  more  flattened  and  sometimes 
curved.    The  apex  of  the  tooth  often  curves  distinctly  toward  the 


EXTRACTION  OF  INDIVIDUAL  TEETH 


595 


cuspid.  The  position  of  the  patient  and  operator  is  practically  the 
same  as  for  the  extraction  of  the  central  incisor.  The  same  forceps 
may  be  used,  and  should  be  adjusted  in  the  same  manner  as  that 
described  in  the  extraction  of  the  central  incisor.  The  forces  used  are 
slight  rotation,  a  little  pressure  labially  and  lingually,.  and  slight 
traction.  The  neck  of  this  tooth  is  sometimes  restricted  to  such  an 
extent  that  some  precaution  must  be  exercised  that  it  is  not  fractured. 


Fig.  466 


Extraction  of  Suyerior  Cusjnd. — Fig.  466  shows  the  position  of  the 
patient  and  the  operator  for  the  extraction  of  the  superior  cuspid  on 
the  right  side.  Fig.  467  shows  the  position  of  the  patient  and  the 
operator  for  the  extraction  of  the  superior  cuspid  on  the  left  side.  This 
tooth  is  one  of  the  most  difficult  teeth  in  the  upper  jaw  to  extract  on 
account  of  its  thickness  labio-lingually  and  the  length  of  its  root,  and  con- 
siderable force  is  often  required  to  break  up  its  attachment  on  account 
of  the  density  and  thickness  of  the  alveolar  process  surrounding  it.  The 
position  of  the  patient  is  the  same  as  for  the  extraction  of  the  central 
and  lateral  incisors.  The  position  of  the  operator  when  extracting 
on  the  right  side  is  slightly  back  of  the  position  for  the  central  and 
lateral,  and  when  extracting  on  the  left  side  it  is  slightly  in  front  of 


596     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

this  position.  The  same  forceps  are  used  for  the  extraction  of  the 
cuspids  as  for  the  lateral  and  central  incisors,  and  are  applied  to  the 
tooth  in  a  similar  manner,  care  always  being  taken  to  force  the  forceps 
well  up  under  the  gingival  margin.  The  forceps  should  be  grasped  with 
much  more  firmness  than  is  required  for  the  extraction  of  the  central  or 
lateral  incisor.  Pressure  labio-lingually  applied  with  an  out-and-in 
motion  and  at  the  same  time  slightly  rotating  will  usually  break  up  the 
attachments.  Slight  force  of  traction  is  then  used  to  remove  it  from 
its  socket.     The  cuspid  next  to  the  lower  third  molar  is  more  often 


Fig.  467 


impacted  or  unerupted  than  any  other.  The  details  of  the  operation 
for  the  removal  of  unerupted  and  impacted  cuspids  will  be  taken  up 
under  the  subject  of  unerupted  and  impacted  teeth. 

Extraction  of  Bicuspids. — Superior  first  and  second  bicuspids.  Fig. 
468  shows  the  position  of  the  patient  and  the  operator  for  the  extraction 
of  superior  bicuspids  on  the  right  side.  Fig.  469  shows  the  position  of 
the  patient  and  the  operator  for  the  extraction  of  superior  bicuspids 
on  the  left  side.  The  technic  of  the  operation  for  the  extraction  of 
the  first   and   second   superior    bicuspids   is   practically    the    same. 


EXTRACTION  OF  INDIVIDUAL   TEETH 


597 


Fig.  468 


Fig,  469 


598     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

The  position  of  the  patient  in  the  chair,  and  that  of  the  operator  is 
practically  the  same  as  that  described  for  the  extraction  of  the  cuspid 
tooth.  The  main  difference  is  in  the  position  of  the  patient's  head; 
when  operating  on  the  right  side,  the  patient's  head  should  be  turned 
to  the  left,  and  when  operating  on  the  left  side,  the  patient's  head 
should  be  turned  slightly  toward  the  operator.  The  forceps  used  for 
this  operation  are  those  shown  in  Fig.  479.  The  movements  used  in 
the  extraction  of  the  bicuspids  are  to  the  buccal  and  lingual,  for  the 
purpose  of  loosening  its   attachment.     In  exerting  such  force  more 


Fig.  470 


pressure  should  be  exerted  to  the  buccal  than  to  the  lingual  for  the 
purpose  of  springing  the  external  plate  of  the  alveolar  process.  After 
the  attachments  are  loosened  the  force  of  traction  should  be  used.  On 
account  of  the  shape  of  the  roots  of  the  first  and  second  bicuspids,  the 
force  of  rotation  should  never  be  used  because  it  may  result  in  fracture 
of  the  roots. 

Extraction  of  Superior  First  and  Second  Molars. — Fig.  470  shows  the 
position  of  the  patient  and  the  operator  for  the  extraction  of  superior 
molars  on  the  right  side.   Fig.  471  shows  the  position  of  the  patient  and 


EXTRACTION  OF  INDIVIDUAL  TEETH 


599 


the  operator  for  the  extraction  of  superior  molars  on  the  left  side. 
The  technic  for  the  operation  of  extracting  the  first  and  second  molars, 
is  practically  the  same  and  will  be  given  together.  For  extraction  of 
superior  molars  the  relative  position  of  patient  and  operator  is  similar 
to  that  for  extraction  of  superior  biscuspids.  The  forceps  used  are 
two  in  number,  one  for  the  right  side,  and  the  other  for  the  left  side. 
These  are  shown  in  Figs.  480  and  481. 

The  beaks  of  the  forceps  should  be  adjusted  to  the  tooth  in  line  with 
its  long  axis  and  forced  well  up  under  the  free  margin  of  the  gum, 


Fig.  471 


sufficiently  so  that  the  point  of  the  buccal  beak  passes  between  the 
buccal  roots.  The  force  used  in  this  operation  is  pressure  first  to  the 
buccal,  then  to  the  lingual  then  with  an  in-and-out  motion  the  tooth 
may  be  loosened  from  its  attachment.  Here  again  greater  pressure 
should  be  brought  to  bear  on  the  buccal  so  that  the  buccal  plate  may 
be  sprung  slightly  outward,  thus  loosening  the  tooth  from  its  attach- 
ment. Then  again  because  of  the  shape  of  the  roots  of  the  molar 
teeth,  it  is  not  practicable  to  bring  a  great  deal  of  pressure  to  the 
lingual  on  account  of  the  long  lingual  root  which  would  oppose  pressure 
in  that  direction.     After  loosening  the  tooth  from   its  attachment. 


600     EXTRACTION  OF   TEETH  AND  SURGICAL  PROCEDURES 

slight  force  of  traction  is  used  to  dislodge  it.  On  account  of  the  shape 
and  number  of  the  roots,  the  force  of  rotation  should  never  be  used 
since  there  is  danger  of  fracturing  one  or  more  roots. 

Extraction  of  Superior  Third  Molars. — ^The  position  of  the  patient  and 
the  operator  will  be  the  same  as  that  for  the  extraction  of  the  first  and 
second  molars.  The  forceps  used  may  be  the  same  or  may  be  especially 
designed  for  superior  third  molars  as  shown  in  Fig.  482.  The  normal 
superior  third  molar  is  usually  not  a  difficult  tooth  to  extract  on  account 
of  the  porosity  of  the  alveolar  process  surrounding  it.  The  roots  are 
usually  fused  together.     The  forceps  should  be  adjusted  well  up  under 


Fig.  472 


the  gingival  margin  and  the  forces  used  should  be  pressure  buccally  and 
lingually  applied  with  an  in-and-out  motion,  and  with  a  slight  rotation 
to  the  buccal  with  more  pressure  brought  to  bear  on  the  buccal  than  the 
lingual,  the  force  of  traction  being  used  for  the  purpose  of  removing  the 
tooth.  Occasionally  the  roots  of  these  teeth  are  spread  widely  apart 
and  in  these  cases  extraction  becomes  more  difficult.  In  some  cases 
the  gum  tissue  is  very  adherent  to  the  distal  surface  of  the  upper  third 
molar  and  great  care  should  be  used  not  to  lacerate  the  soft  tissues 
when  extracting  this  tooth. 


EXTRACTION  OF  INFERIOR   TEETH 


601 


Extraction  of  Inferior  Teeth. — As  a  general  rule,  the  extraction  of  the 
inferior  teeth  is  attended  with  more  difficulties  than  that  of  the  superior 
teeth,  since  they  are  less  accessible  to  the  operator,  and  their  surround- 
ing tissues  are  more  dense.  The  tongue  also  may  sometimes  interfere 
with  the  operation.  The  position  of  the  patient  is  different  from  that 
for  the  extraction  of  the  superior  teeth.  Fig.  472  shows  the  position 
of  the  patient  and  the  operator  for  the  operation  of  extracting  the 
inferior  incisors.     The  head  of  the  patient  should  be  much  lower  than 


Fig.  473 


for  the  extraction  of  the  superior  teeth.  The  operator  should  stand 
at  the  back  and  slightly  to  the  right  of  the  patient.  The  patient's  head 
should  be  straight  in  the  head-rest.  The  left  arm  of  the  operator  is 
placed  around  the  patient's  head  with  the  palm  of  the  hand  supporting 
the  lower  jaw.  The  fingers  of  the  left  hand  are  used  to  retract  the  lips. 
In  the  application  of  the  forceps  to  the  tooth,  the  same  general  principles 
should  govern  the  extraction  of  an  inferior  tooth  as  those  governing  the 
extraction  of  a  superior  tooth.     The  beaks  should  be  in  line  with  the 


602     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

long  axis  of  the  tooth  at  all  times.  When  all  of  the  inferior  teeth  are 
to  be  extracted,  the  central  incisor  should  be  extracted  first,  then  all  of 
the  teeth  on  the  left  side  distally  to  the  molars,  and  then  beginning  at 
the  right  lateral  incisor,  all  the  teeth  distally  to  the  molars  on  the  right 
side.  Then  the  molars  first  on  the  right,  then  on  the  left  should  be . 
taken  in  their  order.  The  lower  jaw  should  have  firm  support  by  the 
left  hand  of  the  operator.  The  jaw  itself  being  movable,  some  difficulty 
may  be  experienced  in  holding  it  rigid  while  the  operation  is  in  progress. 


Fig.  474 


Extraction  of  Individual  Teeth. — Extraction  of  inferior  lateral  and 
central  incisors.  As  the  inferior  central  and  lateral  incisors  are  very 
similar  in  shape  and  size,  the  technic  for  their  removal  will  be  described 
together.  Usually  these  teeth  are  not  very  difficult  to  extract,  their 
roots  being  slightly  conical  in  shape.  Slight  rotation  may  be  indicated 
combined  with  pressure  to  the  labial.  These  movements  will  loosen 
the  attachments.  Then  by  the  force  of  traction  the  tooth  may  be 
removed  from  the  socket.  Occasionally  the  root  of  the  lateral  incisor 
may  be  curved  slightly  to  the  distal,  in  which  case  much  rotation  would 
have  a  tendency  to  fracture  it.  Such  a  tooth  is  removed  in  the  line  of 
least  resistance,  and  pressure  toward  the  cuspid  may  be  used.  The 
lorceps  used  are  those  shown  in  Fig.  484. 


EXTRACTION  OF  INDIVIDUAL   TEETH 


603 


Extraction  of  Inferior  Cuspid. — ^This  tooth  is  usually  more  firmly  set 
in  the  jaw  than  the  incisors.  The  process  surrounding  the  tooth  is 
heavier,  the  roots  of  the  tooth  are  longer  and  heavier  than  the  lateral 
or  central  incisors.  The  position  of  the  patient  and  operator  is 
practically  the  same  as  for  the  extraction  of  the  lateral  and  central 
incisors.  Fig.  473  shows  the  position  of  the  patient  and  the  operator 
for  extracting  the  inferior  cuspid  on  the  right  side.    Fig.  474  shows  the 


Fig.  475 


position  of  the  patient  and  the  operator  for  extraction  of  the  inferior 
cuspid  on  the  left  side.  The  application  of  the  forceps  is  the  same  as 
for  the  lateral  and  central  incisors.  The  tooth  is  loosened  from  its 
attachments  by  the  application  of  pressure  to  the  buccal  with  slight 
rotation.  It  is  then  removed  from  the  socket  by  the  force  of  traction. 
The  forceps  used  are  those  shown  in  Fig.  484. 

Extraction  of  Inferior  Bicuspids. — ^Fig.  475  shows  the  position  of  the 
patient  and  the  operator  for  the  extraction  of  inferior  bicuspids  on  the 


604    EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

right  side.  Fig.  476  shows  the  position  of  the  patient  and  the  operator 
for  the  extraction  of  inferior  bicuspids  on  the  left  side.  The  forceps 
used  are  those  shown  in  Fig.  484.  The  technic  for  the  extraction  of  the 
first  and  second  bicuspids  is  practically  the  same.  The  roots  of  these 
teeth  are  somewhat  flattened  and  sometimes  bifurcated.  The  same 
forceps  are  used  for  the  extraction  of  the  lower  bicuspids  as  for  the  six 
anterior  teeth.  The  position  of  the  patient  and  the  operator  is  similar 
to  that  for  the  six  anterior  teeth.  The  force  of  pressure  to  the  buccal 
is  usually  sufficient  to  break  up  the  attachments,  after  which  the  force 
of  traction  may  be  used  to  remove  the  tooth  from  its  socket. 


Fig.  476 


Molars. — ^Extraction  of  inferior  first  molar.  Fig.  477  shows  the 
position  of  the  patient  and  the  operator  for  the  extraction  of  inferior 
molars  on  the  right  side.  Fig.  478  shows  the  position  of  the  patient 
and  the  operator  for  the  extraction  of  inferior  molars  on  the  left  side. 
When  all  the  teeth  are  in  position,  the  first  molar  is  a  somewhat  diffi- 
cult tooth  to  extract  on  account  of  the  widely  diverging  roots.  When 
operating  on  the  left  side,  the  patient's  head  should  be  turned  slightly 
to  the  right,  and  when  operating  on  the  right  side,  the  patient's  head 
should  be  turned  slightly  toward  the  operator.     The  forceps  used  are 


EXTRACTION  OF  INDIVIDUAL   TEETH 


605 


those  shown  in  Fig.  485.  These  forceps  are  universal  and  can  be  used 
on  either  side.  The  beaks  of  the  forceps  should  be  adjusted  to  the 
tooth  in  the  same  manner  as  in  the  extraction  of  the  anterior  teeth, 
with  the  points  of  the  beaks  well  down  under  the  free  margin  of  the  gum 
and  resting  between  the  mesial  and  distal  roots.  The  forces  used  are 
considerable  pressure  to  the  buccal,  and  traction  to  remove  the  tooth 
from  its  socket.  These  forces  will  usually  break  up  the  attachments. 
Great  care  should  be  exercised  in  the  extraction  of  the  first  molar  so 


Fig.  477 


that  the  mesial  root  does  not  engage  the  second  bicuspid  and  thus 
remove  this  tooth  at  the  same  time. 

Extraction  of  Inferior  Second  Molar. — ^The  inferior  second  molar  is 
not  so  difficult  to  extract  as  the  inferior  first  molar  since  the  roots  are 
not  so  diverging.  The  position  of  the  operator  and  the  patient  is  the 
same,  and  the  application  of  the  forceps  and  forces  used  in  extraction 
are  similar. 

Extraction  of  Inferior  Third  Molar. — The  conditions  involving  the 
inferior  third  molars  are  so  varied  that  a  definite  technic  for  their 


606     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

removal  cannot  be  given  readily.  The  roots  of  a  normal  third  molar 
are  usually  curved  slightly  to  the  distal,  and  for  such  teeth  the  Leclues 
elevator  (Fig.  487)  is  a  very  satisfactory  instrument  to  use  for  their 
removal.  The  point  of  the  elevator  should  be  inserted  into  the  inter- 
proximate  space  between  the  second  and  third  molars,  using  the  alveolar 
process  at  the  cervical  line  as  a  fulcrum,  and  by  a  rotary  force  break  up 
the  attachment.  The  removal  of  the  abnormal  lower  third  molar  will 
be  taken  up  under  a  separate  heading  and  the  technic  will  be  described. 


Fig.  478 


Extraction  of  Deciduous  Teeth. — In  the  extraction  of  deciduous  teeth, 
the  principles  involved  are  the  same  as  those  applied  in  the  extraction 
of  the  permanent  teeth.  One  of  the  principal  features  to  observe  in 
the  extraction  of  deciduous  teeth  is  that  the  developing  permanent 
teeth  be  not  injured  in  the  operation.  This  is  particularly  true  in  the 
removal  of  deciduous  molars  whereby  the  oncoming  permanent  bicuspid 
teeth  may  be  injured  or  may  be  removed  in  the  operation  of  extraction 
of  the  deciduous  molars.  Usually,  if  the  deciduous  teeth  are  extracted 
at  the  proper  time,  there  will  be  little  or  no  difficulty  in  their  removal 
as  at  this  time  the  roots  should  be  completely  decalcified  so  that  the 
crowns  are  held  in  position  only  by  the  soft  tissues.    The  instruments 


EXTRACTION  OF  ROOTS  OF  TEETH  607 

for  the  extraction  of  deciduous  teeth  are  practically  the  same  as  those 
described  in  the  extraction  of  the  permanent  teeth.  In  the  handling 
of  these  little  patients  no  deception  should  be  practiced.  The  patients 
should  be  made  acquainted  with  the  fact  that  there  will  be  some  pain. 
If  they  are  deceived,  subsequent  operations  will  be  performed  with 
much  difficulty  after  the  little  patient  has  once  lost  confidence  in  the 
operator.  Frequently  the  roots  of  the  deciduous  teeth  which  have  not 
resorbed  in  the  process  of  exfoliation  of  the  deciduous  teeth,  will  remain 
in  the  jaws  and  will  become  wedged  between  the  permanent  teeth. 
All  such  roots  should  be  extracted  when  observed.  Frequently  the 
employment  of  an  elevator  for  this  purpose  will  be  more  satisfactory 
than  the  employment  of  forceps. 

Extraction  of  Supernumerary  Teeth. — ^When  supernumerary  teeth  are 
present,  they  are  usually  located  in  the  region  of  the  anterior  teeth. 
Occasionally  they  may  be  found  distally  to  the  third  molar.  When 
these  teeth  are  of  no  permanent  value  to  the  patient,  they  should  be 
removed.  Frequently  these  teeth  will  prevent  the  eruption  of  the 
permanent  teeth,  particularly  in  the  region  of  the  central  incisors. 
The  early  removal  of  them,  therefore,  should  always  be  indicated. 
The  technic  for  extraction  will  not  vary  perceptibly  from  that  for  the 
extraction  of  permanent  teeth. 

Extraction  of  Roots  of  Teeth. — One  of  the  most  common  accidents  in 
the  extraction  of  teeth  is  the  fracture  of  a  tooth,  thus  leaving  certain 
portions  of  the  root  in  the  alveolus.  These  fragments  of  the  root  should 
always  be  removed  because  of  the  danger  of  future  infection.  They 
may  be  removed  by  alveolar  forceps  or  by  elevators.  The  alveolar 
forceps  may  sometimes  be  used  very  satisfactorily  on  roots  in  either 
the  superior  or  inferior  maxilla.  The  forceps  for  superior  roots  are 
those  illustrated  in  Fig.  483.  They  consist  of  long  narrow  beaks  and 
sharp  edges  for  the  purpose  of  cutting  through  the  alveolar  process. 
The  technic  for  the  extraction  of  these  roots  is  to  insert  the  beaks  of 
these  forceps  well  up  under  the  free  margin  of  the  gum  mitil  the 
operator  is  sure  that  solid  tooth  structure  will  be  encountered,  and  with 
the  sharp  edges  of  the  beaks  to  cut  through  the  alveolar  process,  until 
the  forceps  come  into  contact  with  the  root  to  be  extracted.  Then  by 
the  force  of  rotation  and  traction  the  root  is  removed  from  the  socket. 
This  same  technic  should  be  used  for  the  extraction  of  teeth  that  have 
decayed  under  the  free  margin  of  the  gmn.  In  the  inferior  maxilla 
the  technic  is  similar,  using  the  lower  alveolar  forceps  as  illustrated  in 
Fig.  484.  On  account  of  the  density  of  the  alveolar  process,  elevators 
may  be  used  more  advantageously  than  the  forceps  when  one  is  operat- 
ing distally  to  the  cuspid  teeth.  The  elevators  for  the  removal  of  roots 
which  are  very  satisfactory  are  those  illustrated  in  Fig.  486  known  as  the 


608     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

Cryer  elevators.  The  method  of  procedure  is  to  engage  a  portion  of 
the  root  with  the  point  of  the  elevator,  using  the  alveolar  process  as  a 
fulcrum  and  rotating  the  root  out.  In  the  multi-rooted  teeth  sometimes 
the  socket  of  one  root  may  be  used  as  point  of  access  to  the  fractured 
root.  In  roots  which  have  been  exostosed  it  may  sometimes  be 
necessary  to  cut  away  the  alveolar  plate  with  a  drill  in  order  to  remove 
the  root.    This  is  best  done  by  drills  illustrated  in  Fig.  492, 

Instruments. — ^The  instruments  used  in  the  extraction  of  teeth  are 
forceps,  elevators,  chisels,  drills,  lancets,  gum  scissors,  and  mouth 
gags  and  curettes.  The  proper  selection  of  suitable  instruments  is  a 
matter  of  considerable  importance  and,  since  much  depends  upon  the 
instrmnents  in  this  operation,  a  judicious  selection  of  them  should  be 
made.  The  mastery  of  the  application  of  a  few  instruments  is  better 
than  a  little  knowledge  of  the  application  of  many.  The  principal 
instruments  for  the  extraction  of  teeth  are  the  forceps.  The  operator 
should  have  a  well  selected  set  so  that  he  may  become  thoroughly 
familiar  with  every  detail  in  their  application.  The  principal  features 
of  the  forceps  which  should  be  taken  into  consideration  in  selecting 
them  are  the  beaks,  joints,  and  handles.  The  beaks  should  be  so 
constructed  that  they  will  fit  the  tooth  for  which  they  are  intended. 
The  ends  of  the  beaks  should  be  thin  so  that  they  may  be  inserted  under 
the  free  margin  of  the  gum  with  ease.  The  beaks  should  be  bent  at  an 
angle  with  the  handle  so  that  the  tooth  may  be  grasped  in  line  with  its 
long  axis  and  permit  of  the  extraction  of  the  tooth  without  the  inter- 
ference of  the  handles  of  the  forceps  with  the  cheeks  and  lips  of  the 
patient.  To  allow  for  an  easy  opening  and  closing  of  the  beaks,  the 
joints  of  the  forceps  should  have  free  play.  The  edges  of  the  joints 
should  be  rounded  to  avoid  engaging  the  soft  tissues  in  them  while 
operating.  The  handles  should  conform  in  so  far  as  possible,  to  the 
hand  of  the  operator.  By  constant  use  of  the  forceps  the  operator  soon 
becomes  accustomed  to  the  feeling  of  them  in  his  hands.  All  of  the 
forceps  for  the  superior  teeth  should  have  full-ended  handles  (Figs.  479 
to  485)  to  assist  the  operator  in  forcing  the  beaks  of  the  forceps  up  under 
the  free  margin  of  the  gums.  For  the  inferior  teeth  the  handles  should 
be  curved  so  as  to  fit  the  hand.  One  of  the  handles  should  be  shorter 
with  a  curved  end  to  the  handle  which  fits  over  the  little  finger  when  the 
forceps  are  put  into  application.  The  following  forceps  have  been 
selected  for  the  extraction  of  teeth  because  of  the  broad  range  of 
usefulness.  It  is  not  possible  nor  practicable  to  give  a  complete  descrip- 
tion of  all  of  the  forceps  that  might  be  used  in  the  extraction  of  teeth. 
It  is  believed  that  if  the  operator  will  perfect  his  technic  with  a  few  well 
selected  forceps  he  will  become  more  proficient. 


L._ 


IarcI 


Fig.  479 


39 


Fig.  480 


Fig.  481 


flARC 


Fig.  482 


Fig.  483 


IXSTBVMEXTS 


613 


Forceps  for  Superior   Trcfh. — For  the  superior  teetli  tlie    following 
forceps  are  essential: 


Fig.  484 


Fig.  4S5 


Standard  forceps  Xo.  1,  Fig.  479  for  central  lateral  incisors,  cuspids 
and  biscuspids.  Both  beaks  are  alike  and  set  in  line  with  the  axis  of 
the  handles. 


614    EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

Standard  forceps  No.  3R  and  ;3L,  right  and  left  (Figs.  4S0  and  481), 
for  first  and  second  molars.  These  forceps  may  be  used  also  for  the 
third  molars.  The  end  of  the  buccal  beak  comes  to  a  point  so  as  to  fit 
between  the  mesial  and  distal  buccal  roots.  The  lingual  beak  is  oval. 
The  beaks  are  set  about  two  centimeters  out  of  line  with  the  axis  of 
the  handle. 

Standard  forceps  No.  4  for  third  molars  (Fig.  482),  which  are  appli- 
cable to  both  sides  of  the  arch.  Both  beaks  are  alike  and  set  about 
two  centimeters  out  of  line  with  the  axis  of  the  handles. 

Standard  forceps  No.  2  and  Standard  forceps  No.  5  (Fig.  483),  for 
roots  of  all  of  the  upper  teeth.  Standard  forceps  No.  2  may  also  be 
used  for  the  extracting  of  the  upper  bicuspids.  Both  beaks  are  alike 
and  set  about  two  centimeters  out  of  line  with  the  axis  of  the  handles. 
Standard  forceps  No.  5,  has  long  and  narrow  beaks  which  are  slightly 
curved  in  their  mesio-distal  axis. 

Forceps  for  the  Inferior  Teeth. — Standard  forceps  No.  6  for  central 
lateral  incisors,  cuspids,  and  bicuspids  (Fig.  484) .  These  may  also  be 
used  as  alveolar  forceps  in  the  extraction  of  all  of  the  roots  of  the 
inferior  teeth.  Both  beaks  are  alike  and  set  at  an  obtuse  angle  with 
the  handles. 

Standard  forceps  No.  7  universal,  for  lower  molars  on  both  sides  of 
the  jaws  (Fig.  485) .  Both  beaks  are  alike  and  set  at  an  obtuse  angle 
with  the  handles. 

Elevators. — ^Elevators  may  be  used  to  advantage  in  the  removal  of 
lower  third  molars^  roots,  and  impacted  teeth.  Fig.  486  shows  the 
Cryer  elevator.  All  elevators  should  have  metal  handles  so  that  they 
may  be  sterilized  by  boiling.  This  elevator  is  used  in  the  extraction  of 
roots;  the  operator  using  the  point  to  engage  the  side  of  the  root  and 
with  the  alveolar  process  as  a  fulcrum  rotates  them  out.-  The  Lecluse 
or  spade  elevator  (Fig.  487) ,  is  useful  in  the  extraction  of  the  lower  third 
molar  and  for  rotating  out  impacted  teeth.  The  point  and  straight 
side  of  the  elevator  are  used  to  engage  the  side  of  the  root  or  tooth 
allowing  the  rounded  surface  to  rotate  on  the  alveolar  process  while 
the  tooth  or  root  is  being  forced  out  of  the  socket.  The  shank  of  this 
elevator  may  be  straight  or  it  may  be  canted  at  an  angle  to  conform 
with  the  position  of  the  mouth  in  which  it  is  used.  Fig.  488  shows  the 
Jones  elevator.  It  is  designed  somewhat  after  the  Lecluse  elevator. 
It  has  a  long  narrow  shank  with  a  thin  blade.  This  elevator  is  used  in 
the  removal  of  lower  third  molars.  The  blade  is  inserted  between  the 
second  and  third  molars  with  the  flat  surface  toward  the  third  molar, 
then  by  a  rotary  motion  the  third  molar  is  loosened  from  its  attach- 
ments. This  elevator  may  also  be  used  in  the  dislodgement  of  roots 
of  teeth  by  placing  the  point  of  the  elevator  between  the  alveolar 


INSTRUMENTS  615 

process  and  the  tooth,  engaging  the  tooth  root  with  the  point  of  the 
elevator,  and  forcing  the  root  from  its  socket.    Fig.   489  shows  the 


Fig.  486 


Heidbrink  elevator.    This  is  designed  especially  for  roots  in  the  ante- 
rior part  of  the  mouth  when  the  decay  has  so  far  progressed  that  the 


616     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

use  of  a  forcep  cannot  be  satisfactorily  employed.  It  is  used  by  insert- 
ing the  blade  in  the  interproximate  space  and  forcing  it  between  the 
alveolar  process  and  the  root,  or  it  may  be  used  between  the  buccal 
plate  of  the  alveolar  process  and  the  root  for  the  purpose  of  loosening 


Fig.  487 


Fig.  488 


INSTRUMENTS 


617 


the  root.     Fig.  490  shows  the  Crane  elevator.     This  elevator  has  the 
shape  of  an  ice  pick  and  can  be  used  advantageously  in  the  removal  of 


Fig.  489 


Fig.  490 


upper  thu-d  molars  by  forcing  the  point  of  the  elevator  through  the 
alveolar  process,  engaging  the  third  molar  v^ith  its  point,  and  with  a 
prying  motion  loosening  the  tooth  from  its  attachment. 


618     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

Chisels. — Yig.  491  shows  the  Lyons  chisel-elevators.  These  instru- 
ments may  be  employed  in  the  removal  of  impacted  third  molars. 
These  are  the  carpenter's  edge  chisels  and  are  so  designed  that  they 


INSTRUMENTS 


619 


may  be  used  as  ele^'ato^s  as  well  as  chisels.     They  may  be   used  as 
hand  chisels  or  vnth  the  mallet. 

Drills. — ^Fig.  492  shows  the  Henahan  surgical  bone  drill.  This  may 
be  used  for  the  piu-pose  of  cutting  away  the  alveolar  process  around 
tooth  roots  or  cutting  away  the  buccal  plate  around  the  alveolar 
process  siu-rounding  impacted  third  molars. 


Fig.  492 

Lancets. — ^Fig.  493  shows  a  gum  lancet.  It  should  be  of  all-metal 
construction  so  that  it  can  be  sterilized.  The  lancet  is  used  to  sever 
the  soft  tissues  around  the  teeth  ^o  as  to  prevent  laceration  of  the 
tissues  in  the  process  of  extraction  by  the  soft  tissues  adhering  to  the 
tooth.    Unless  we  have  reason  to  believe  that  the  soft  tissues  are 


Fig.  493 


adhering  to  the  tooth,  the  lancet  should  rarely  be  employed  previous 
to  the  extraction,  because  hemorrhage  from  the  incision  of  the  lancet 
might  interfere  with  the  operation. 

Gum  Scissors. — ^Fig.  494  shows  curved  scissors.  This  instrument 
may  be  used  advantageously  in  trimming  gimi  tissues  around  the 
alveolar  socket  follo^^■ing  extraction.     It  may  also  be  used  in  severing 


620    EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

the  soft  tissues  from  the  tooth  to  prevent  laceration.  The  scissors 
may  be  used  to  advantage  in  trimming  the  soft  tissues  following  the 
operation  of  alveolectomy. 


Fig.  494 


Mouth  Gags. — ^The  mouth  gag  is  a  very  valuable  and  indispensable 
instrument  for  the  dentist  to  have  when  extracting  under  a  general 
anesthetic.  Fig.  495  shows  a  soft  rubber  mouth  gag  which  is  very 
efficient  for  retaining  the  mouth  open  during  the  process  of  anesthesia. 
When  using  a  metal  mouth  gag,  it  is  advisable  to  have  a  rubber  protec- 
tion over  the  jaws  of  it,  so  as  to  prevent  injury  to  the  tooth  surfaces. 
Fig.  496  shows  a  metal  mouth  gag  which  is  very  satisfactory  when 
operating  around  the  mouth.     The  handles  are  away  from  the  field  of 


ACCIDENTS  DURING  THE  PROCESS  OF  EXTRACTING  TEETH     621 

operation,  and  will  not  interfere  with  the  mask  or  face-piece  in  the 
administration  of  a  general  anesthetic.  The  gag  should  be  applied 
always  on  the  side  opposite  the  field  of  operation. 


Fig.  495 

Fig.  497  shows  the  Bogle  curettes.  These  instruments  may  be  used 
following  the  extraction  of  abscessed  teeth  and  the  operation  of  apicoec- 
tomy  for  mechanically  eliminating  infected  areas.  They  may  be  used 
also  in  any  place  where  diseased  tissue  should  be  removed.  The 
handles  are  large  and  will  permit  of  considerable  pressure  upon  the 
blades  of  the  instruments.  The  blades  are  spoon  shaped  with  sharp 
cutting  edges. 

Accidents  During  the  Process  of  Extracting  Teeth. — Accidents  will 
happen  frequently  during  the  process  of  extracting  teeth,  and  the 
operator  should  be  familiar  with  all  of  the  features  of  such  accidents 
and  should  aim  to  prevent  them  whenever  possible.  There  are  many 
accidents  which  are  wholly  unavoidable  in  the  operation  of  extracting 
teeth.  There  are  many  more  which  are  avoidable  but  which  frequently 
happen  to  the  beginner.  When  these  accidents  occur,  the  operator 
should  not  become  confused,  but  should  remain  composed  so  as  not  to 
excite  the  patient.  When  it  is  necessary  the  patient  should  be  made 
acquainted  with  all  the  facts  concerning  the  accident;  this  procedure 
will  instill  assurance  and  confidence  in  the  patient.  One  of  the  most 
common  accidents  which  occurs  in  the  extraction  of  teeth  is  the 


622     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

fracture  of  a  root.  Such  accidents  may  be  avoided  by  making  a  careful 
survey  of  not  only  the  tooth,  but  the  anatomic  structures  surrounding 
the  tooth  before  proceeding  with  the  operation;  then  by  the  selection 
of  instruments  adapted  to  the  operation,  many  of  these  fractures  may 
be  avoided.    Much  will  depend  upon  the  proper  apphcation  of  the 


Fig.  496 


"forceps,  and  the  movements  which  are  required  to  loosen  the  tooth 
from  its  attachments.  Much  will  also  depend  upon  the  correct  posi- 
tion of  the  patient  in  the  chair.  In  all  cases  of  extraction,  the  operation 
should  not  be  done  too  rapidly  because  that  is  one  of  the  causes  of 
many  fractured  roots.    The  patient  may  interfere  with  the  proper 


ACCIDENTS  DURING  THE  PROCESS  OF  EXTRACTING  TEETH     623 


Fig.  497 


624     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

application  of  forces  by  the  operator,  by  grasping  the  operator's  hands 
or  arms  and  this  might  predispose  to  fracture  of  the  tooth.  The  roots 
of  the  teeth  may  be  abnormal  in  shape  which  fact  may  result  in  fracture 
of  the  roots  during  the  operation.  Whenever  a  fracture  of  a  tooth 
occurs,  the  roots  should  always  be  removed.  It  is  not  permissible  to 
leave  a  portion  of  the  tooth  root  in  the  socket,  on  account  of  the 
probable  chances  of  infection  following  later. 

Fracture  of  the  Alveolar  Process. — A  fracture  of  the  external  plate  of 
the  alveolar  process  is  not  an  infrequent  accident  following  the  extrac- 
tion of  upper  molar  teeth.  This  fracture  may  be  so  extensive  that  the 
antral  cavity  will  be  opened.  When  such  an  accident  occurs  the 
patient  should  be  made  aware  of  the  fact,  and  the  muco-periosteum 
covering  the  walls  of  the  antrum  should  be  sutured  back  in  normal 
position.  The  posterior  portion  of  the  alveolar  process  and  the 
maxillary  tuberosity  may  be  fractured  in  the  removal  of  an  upper 
third  molar  tooth.  This  may  occur  from  two  causes:  first,  if  the  beaks 
of  the  forceps  are  improperly  applied  to  the  tooth  so  that  the  beaks 
grasp  the  alveolar  plate  instead  of  the  tooth,  fracture  may  result  when- 
the  forces  of  extraction  are  applied;  second,  in  some  individuals  the 
alveolar  plate  is  so  thin  that  when  there  is  a  calcification  of  the  peri- 
cemental membrane  and  adhesion  of  the  membrane  to  the  alveolar 
process,  the  force  required  to  remove  the  tooth  may  fracture  the 
tuberosity.  These  injuries  should  not  be  considered  serious  as  com- 
plete repair  will  take  place  almost  as  rapidly  as  if  no  fracture  had  been 
made.  Such  a  fracture  can  easily  happen  under  a  general  anesthetic 
when  the  operator  may  be  operating  with  undue  haste. 

Another  accident  which  may  occur  on  account  of  a  hasty  operation 
is  that  of  extracting  the  wrong  tooth.  An  accident  of  this  kind  is 
wholly  unwarranted.  The  operator  should  be  very  careful  especially 
when  extracting  under  a  general  anesthetic,  to  see  that  the  beaks  of  the 
forceps  are  placed  upon  the  proper  tooth  before  using  the  forces  of 
extraction.  Even  when  this  has  been  done,  the  removal  of  a  tooth 
adjacent  to  the  tooth  to  be  extracted  may  occur.  The  roots  of  these 
teeth  may  be  partially  fused  together  or  the  roots  of  one  may  be  so 
shaped  that  they  will  engage  the  other,  thus  making  the  extraction  of 
one  without  the  other  extremely  difficult.  When  an  adjacent  tooth  is 
removed  accidentally,  it  should  be  immediately  replanted  and  ligated 
to  approximating  teeth.  Following  this  procedure,  the  pulp  of  the 
tooth  should  be  removed  and  the  canal  filled.  The  injury  of  unerupted 
permanent  teeth  may  occur  when  extracting  deciduous  teeth.  This 
may  occur  by  the  beaks  of  the  forceps  being  inserted  top  deeply  and 
engaging  the  crown  of  the  permanent  tooth.  In  rare  cases  the  roots 
of  the  deciduous  teeth  may  be  attached  or  engaged  to  the  crowns  of 


FRACTURE  OF   THE  ALVEOLAR  PROCESS  625 

the  permanent  teeth,  such  as  the  deciduous  molar  tooth  root  being 
attached  to  the  permanent  bicuspid,  and  the  removal  of  the  molar 
might  loosen  the  bicuspid  attachment  to  such  an  extent  that  both 
teeth  might  be  removed  together.  In  the  removal  of  a  superior  bicus- 
pid or  molar,  there  is  a  possibility  of  forcing  a  part  or  whole  of  the 
tooth  into  the  antral  cavity  by  permitting  the  forceps  to  slip  from  the 
tooth  or  root  in  the  process  of  extracting,  and  forcing  the  tooth  through 
the  thin  wall  of  the  antrum.  It  should  always  be  removed  even  though 
a  radical  antral  operation  be  performed.  It  is  never  permissible  to 
leave  such  a  foreign  body  in  the  maxillary  sinus.  This  accident  may 
occur  in  forcing  the  root  into  an  abscessed  cavity  which  has  been 
formed  in  either  upper  or  lower  jaws.  In  these  casss  the  ends  of  the 
roots  should  always  be  accounted  for,  and  the  cavity  should  be  suffi- 
ciently opened  to  permit  exploration  of  all  its  walls.  In  the  removal  of 
an  upper  third  molar,  the  operator  may  force  it  up  into  the  spheno- 
maxillary fossa  where  it  may  become  lodged  so  that  the  position  of  it 
can  be  ascertained  only  by  the  use  of  the  roentgen  ray.  When  such  an 
accident  occurs,  the  patient  should  be  apprised  of  the  conditions,  and 
the  tooth  should  be  removed.  In  either  the  upper  or  lower  jaws  it  is 
always  possible  to  force  a  tooth  between  the  soft  tissues  and  alveolar 
process.  In  the  lower  jaw  the  tooth  may  be  forced  as  deep  as  the 
submaxillary  fossa.  In  these  cases,  an  explorer  should  be  used  to 
locate  the  tooth,  then  by  a  properly  shaped  hemostatic  forcep  and 
curved  instruments,  the  tooth  should  be  teased  out.  In  those  accidents 
where  the  soft  tissues  are  lacerated,  it  is  good  practice  after  sterilizing 
the  wound,  to  suture  the  mucous  membrane  as  repair  will  take  place 
much  more  rapidly. 

A  quite  common  accident  which  occurs,  is  the  loosening  of  an  adja- 
cent tooth  or  teeth.  This  is  not  serious,  and  by  pressing  back  the  tooth 
into  its  position,  rapid  repair  will  take  place.  A  crown  or  inlay  may  be 
removed  easily  in  the  extraction  of  teeth.  By  close  examination 
previous  to  the  operation,  the  operator  may  see  the  possibility  of  such 
an  accident,  and  he  should  acquaint  the  patient  mth  the  possibility 
so  that  if  it  occurs,  the  patient  will  not  censure  the  operator.  A  porce- 
lain crown  may  be  fractured  easily  by  the  instruments  being  forcibly 
brought  in  contact  mth  it  during  the  operation.  During  the  adminis- 
tration of  general  anesthesia,  when  a  mouth  gag  is  used,  the  instriunent 
should  not  come  in  contact  vdth  porcelain  facings  on  account  of  the 
possibility  of  fracture.  Injury  to  the  lips  and  adjacent  tissues  by 
mouth  gags  should  always  be  avoided. 

The  breaking  of  a  point  of  an  elevator  or  other  instrument  in  the 
process  of  extraction  is  an  accident  that  occasionally  occm-s,  and  when 
it  does,  the  point  of  the  elevator  or  other  instrument  should  be  remo\'ed 
40 


626     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

entirely.  The  wounding  of  the  tongue,  cheeks  or  floor  of  the  mouth 
is  an  accident  that  may  occur  during  the  extraction  under  a  general 
anesthetic.  Such  accidents  occur  for  the  reason  that  the  mouth  is 
filled  with  blood  and  the  field  of  operation  is  obscured  so  that  the 
forceps  are  improperly  applied.  When  operating  under  a  general 
anesthetic  the  operator  should  always  have  a  clear  field  before  him. 
This  can  be  accomplished  by  the  use  of  sponges.  When  such  an 
accident  occurs  sutures  should  be  used  to  restore  the  parts  to  normal 
condition. 

Another  accident  that  may  occur  is  the  dislocation  of  the  mandible. 
This  may  happen  to  those  patients  who  are  subject  to  habitual  disloca- 
tion of  the  jaws,  or  it  may  occur  with  any  other  patient  where  undue 
force  is  exerted  in  the  endeavor  to  remove  a  lower  molar  tooth.  When 
this  occurs  a  reduction  of  the  dislocation  should  be  made  immediately. 
This  can  be  accomplished  by  placing  a  block  of  wood  between  the 
molars,  and  by  pressing  upward  on  the  symphysis,  and  at  the  same  time 
causing  considerable  backward  pressure,  the  head  of  the  condyle  thus 
being  forced  back  into  the  glenoid  fossa. 

Another  accident  that  may  sometimes  occur  in  the  removal  of  lower 
third  molars  is  a  fracture  of  the  mandible  at  the  angle  of  the  jaw. 
This  usually  occurs  on  account  of  too  much  force  being  applied  in  the 
attempt  to  dislodge  the  tooth.  Such  an  accident  may  also  occur  by 
cutting  away  so  much  of  the  mandible  in  an  endeavor  to  release  the 
tooth  that  it  becomes  weakened.  It  will  occur  more  frequently  in 
older  than  in  the  younger  patients.  When  this  accident  occurs,  the 
mandible  should  be  immobilized  by  interdental  ligation.  The  lower 
jaw  should  be  immobilized  for  a  period  of  four  or  five  weeks. 

Another  accident  that  may  occur  particularly  in  the  administration 
of  general  anesthesia  is  that  of  a  tooth  slipping  from  the  beaks  of  the 
forceps  in  the  process  of  the  operation  and  passing  into  the  pharynx. 
This  accident  may  be  avoided  by  operating  slowly  and  in  those  cases 
where  there  is  not  good  access  to  the  field  of  operation,  a  sponge  should 
be  placed  back  in  the  pharynx  during  the  operation  so  that  no  foreign 
body  may  drop  into  it.  In  the  extraction  of  teeth  under  a  general 
anesthetic,  when  there  is  considerable  hemorrhage,  it  is  best  to  use  an 
aspirator  for  the  purpose  of  keeping  the  blood  out  of  the  pharynx. 
Pneumonia  may  be  avoided  by  so  doing. 

Hemorrhage  Following  Extraction. — ^Hemorrhage  following  extraction 
may  be  arterial,  venous,  or  capillary  in  character,  depending  upon  the 
vessel  from  which  the  blood  escapes.  When  arterial,  it  is  usually 
located  in  the  socket  of  the  tooth  and  may  be  stopped  by  packing 
firmly  the  socket  with  medicated  gauze  or  absorbent  cotton.  Before 
inserting  the  cotton  or  gauze,  it  is  good  practice  to  roll  the  cotton  in 


HEMORRHAGE  FOLLOWING  EXTRACTION  627 

Monsel's  solution  or  in  tannic  acid,  or  use  it  in  connection  with  adrena- 
lin chlorid  for  the  purpose  of  contracting  the  arterial  walls.  Adrenalin 
chlorid  is  a  powerful  vasomotor  constrictor,  and  one  of  the  most  power- 
ful hemostatics  known.  Although  its  effects  do  not  last  long  after 
the  hemorrhage  has  once  ceased,  it  is  not  difficult  to  keep  it  under 
control.  A  pledget  of  cotton  rolled  to  the  shape  of  the  tooth  socket  and 
dipped  in  sterile  sandarac  varnish  is  very  efficient  in  blocking  off  the 
hemorrhage.  A  modeling  compound  impression  of  the  socket  may  be 
made  and  after  it  hardens  it  is  withdrawn  and  coated  with  soft  plaster 
of  paris  and  again  inserted  and  held  until  the  plaster  of  paris  hardens. 
This  packing  mil  completely  adapt  itself  to  any  part  of  the  socket 
and  block  ofi^  any  vessel.  It  T\dll  also  remain  in  the  socket  with- 
out retention  of  any  kind.  In  those  cases  in  which  it  is  necessary 
to  cause  pressure  upon  the  wound  in  order  to  control  the  hemorrhage, 
gauze  or  absorbent  cotton  should  be  placed  between  the  jaws  over  the 
wound,  using  a  figm-e-of-eight  or  Barton's  bandage  to  bind  the  jaws 
together. 

In  the  removal  of  several  teeth  there  may  be  considerable  hemor- 
rhage follo\dng,  particularly  in  anemic  individuals,  and  it  may  test  the 
ingenuity  of  the  operator  to  ascertain  the  best  means  of  control.  If 
the  hemorrhage  is  coming  from  more  than  one  tooth  socket,  that  fact 
should  be  ascertained,  and  each  socket  treated  separately  until  the 
hemorrhage  has  subsided.  In  cases  of  hemorrhagic  diathesis  the 
treatment  should  be  begun  before  extracting.  If  the  patient  presents 
with  a  history  of  bleeding,  then  he  shoidd  be  placed  under  the  care 
of  a  physician  for  two  or  three  weeks  previous  to  the  extraction  of 
the  teeth.  In  such  a  case,  the  blood  does  not  coagulate  normally  and 
will  be  very  slow  in  forming  a  clot.  It  is  also  possible  in  such  a  case 
that  the  walls  of  the  vessels  have  lost  their  tone  so  that  the  severed 
vessels  do  not  contract  normally  to  close  the  lumen.  ^Mien  the 
patient  is  in  good  health  a  hemorrhage  will  cease  usually  by  a  proper 
coagulation  and  the  normal  contraction  of  the  vessels.  This  abnormal 
condition  of  hemorrhagic  diathesis  is  brought  about  by  certam  diseases, 
and  an  early  examination  should  be  made  in  these  cases  by  a  physician 
before  operating  on  many  teeth. 

"Whenever  it  is  necessary  to  operate,  the  administration  of  calcium 
lactate  10  to  15  grains,  three  or  four  times  per  day  before  the  operation 
will  sometimes  be  of  aid  in  the  forming  of  prompt  coagulation.  When 
the  patient  presents  with  such  a  history,  it  is  not  best  to  open  too  much 
tissue  at  once;  extraction  of  a  single  tooth  at  a  time  is  always  best. 

If  the  hemorrhage  is  severe,  it  may  be  controlled  by  the  injection 
of  horse  serum  in  10  c.c.  doses.  This  promotes  coagidation.  Death 
rarely  follows  as  a  result  of  hemorrhage  after  the  extraction  of  a  tooth. 


628     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

However,  there  may  be  marked  constitutional  symptoms  as  the  result 
of  the  loss  of  blood.    In  these  cases  the  general  appearance  of  the 
patient  is  changed  from  the  normal.    The  lips,  ears,  conjunctiva,  as 
well  as  the  general  integument  are  of  a  yellow  color.    The  general 
appearance  of  the  patient  is  pinched  or  shriveled.    The  body  is  bathed 
in  a  general  sweat,  the  pupils  dilated.    Because  the  brain  is  anemic, 
humming  or  roaring  sounds  are  heard.    The  general  sensibility  is 
benumbed,  and  if  the  loss  of  blood  is  severe,  unconsciousness  follows. 
In  these  cases,  the  first  thing  to  do  is  to  control  the  hemorrhage,  after 
which  stimulants  are  to  be  given  the  patient  such  as  strong  whisky 
or  brandy.    When  the  patient  has  not  been  anesthetized,  ether  is  a 
good  stimulant  to  ward  off  syncope.    Atropia,  j^q  grain  doses  act  as 
a  respiratory.    External  heat  by  hot  water  bottles  should  be  used 
diligently.    Normal  salt  solution  100°  to  105°  F.  as  it  emerges  from  the 
needle  should  be  injected  into  a  vein  or  the  soft  tissue  of  the  breast, 
the  abdomen,  or  the  rectum.     Injection  into  the  breast  or  abdomen 
requires  no  special  apparatus  but  a  large  size  hypodermic  needle.     A 
great  loss  of  blood  may  bring  on  a  condition  commonly  known  as  shock.  - 
Pre-operative  Treatment  in  the  Extraction  of  Teeth. — ^Bacteria,  as  a 
rule,  gain  entrance  into  the  human  system  through  rupture  of  the 
tissues.    A  wound,  an  abrasion,  and  an  inflamed  or  injured  part  pre- 
pare the  way  for  bacteria  by  lowering  the  local  resistance.    After  this, 
if  followed  by  a  profound  constitutional  depression,  due  to  exposure, 
excesses  or  disease,  the  growth  of  bacteria  will  be  rapid  and  destructive. 
The  extraction  of  a  tooth  necessarily  opens  the  tissues  and  prepares  the 
way  for  the  entrance  and  propagation  of  microorganisms.     In  order 
to  limit  the  number  of  microorganisms  which  may  enter  the  system 
through  a  wound,  prophylactic  measures  should  be  instituted  previous 
to  the  extraction  of  a  tooth.    These  prophylactic  measures  should 
consist  of  spraying  out  the  mouth  with  a  normal  salt  solution  just 
previous  to  the  operation.    This  should  be  followed  by  painting  the 
field  of  operation  with  a  7  per  cent,  solution  of  tincture  of  iodin  to 
remove  the  gross  sepsis.     It  should  be  understood  that  all  instruments 
connected  with  extraction  of  teeth  should  be  sterilized  on  the  same 
plan  as  instruments  are  sterilized  for  any  other  surgical  operation. 
The  instruments  should  be  boiled  for  at  least  fifteen  minutes  previous 
to  using  them.    The  aim  should  be  to  reduce  the  number  of  micro- 
organisms that  might  possibly  enter  the  system  through  the  wound. 

Post-operative  Treatment. — ^Any  accident  that  may  have  occurred 
during  the  operation  of  extraction  should  be  recognized  at  once  by  the 
operator  and  treatment  instituted  as  circumstances  warrant.  All 
loose  portions  of  the  processes  or  loose  pieces  of  the  gum  tissues  should 
be  removed  following  the  extraction.    When  there  has  been  no  patho- 


POST-OPERATIVE  PAINS  629 

logic  condition  present,  when  the  gum  tissue  has  not  been  contused 
or  lacerated,  and  when  there  have  been  no  overhanging  ragged  edges 
of  the  alveolar  process,  irrigating  immediately  with  a  5  per  cent,  salt 
solution  will  usually  yield  good  results.  This  irrigation  will  flush  out  any 
debris  that  may  have  entered  and  lodged  in  the  tooth  socket.  The 
primary  hemorrhage  which  follows  the  extraction  will  usually  cease  in 
a  few  minutes  and  a  blood  clot  will  be  formed,  which  acts  as  a  scaf- 
folding, through  which  normal  repair  will  take  place.  The  blood  clot 
will  protect  the  wound  during  the  process  of  repair  so  that  in  these 
simple  cases  further  dressing  will  not  be  indicated. 

The  patient  should  be  instructed  to  irrigate  the  mouth  daily  with  a 
5  per  cent,  salt  solution.  Simple  cases  of  extraction  wliich  are  treated 
in  this  manner  will  usually  cause  no  further  trouble.  In  cases  of 
difficult  extraction  when  there  has  been  considerable  traumatism  to  the 
tissues,  a  condition  of  alveolitis  may  follow  the  operation.  Immediately 
following  such  an  operation,  the  socket  should  be  irrigated  with  a  5  per 
cent,  salt  solution  and  counter-irritants  such  as  aconite  and  iodin  or 
iodized  phenol  used  to  allay  the  inflammation.  The  patient  should 
return  every  day  for  treatment  until  the  Inflammatory  condition  subsides. 
In  these  cases,  it  is  necessary  to  keep  the  field  scrupulously  clean.  All 
of  the  body  eliminating  processes  should  be  made  active. 

When  there  has  been  a  stripping  off  of  the  muco-periosteum  to  any 
great  extent  over  the  alveolar  process,  it  should  be  sutured  back  into 
normal  position,  using  horse  hair  or  dermal  suture  for  this  pinpose. 
In  cases  of  extraction  of  teeth  with  alveolar  abscess,  the  sockets  should 
be  thoroughly  curetted  following  the  operation.  Spoon  shaped  hand 
curettes  are  the  most  desirable  for  this  procedure. 

In  a  case  of  extraction  of  a  tooth  with  a  granuloma  at  the  apical  end, 
the  same  procedure  should  be  instituted.  In  many  cases  it  will  be 
necessary  to  remove  the  buccal  plate  over  the  sockets  of  the  teeth  in 
curetting,  so  that  every  surface  of  the  abscess  cavity  may  be  explored. 
Following  the  curettage,  the  cavity  should  be  irrigated  and  the  treat- 
ment instituted  as  for  all  other  extractions.  In  case  pus  is  present 
following  extraction  of  an  abscessed  tooth,  packing  the  socket  for 
twenty-four  hours  with  iodoform  gauze  for  the  purpose  of  maintaining 
drainage  is  good  procedure,  after  which  the  same  treatment  as  in  other 
extractions  will  yield  good  results.  All  precautions  should  be  used  in 
the  extraction  of  teeth  to  prevent  infection  following  the  operation, 
but  if  infection  occurs,  it  should  be  treated  in  the  same  manner  as  an 
infection  that  is  present  at  the  time  of  extraction. 

Post-operative  Pains. — The  patients  should  be  acquainted  with  the 
fact  that  in  all  probability  there  will  be  some  pain  followhig  the 
operation  of  extracting  a  tooth.     They  should  be  informed  that  a 


630     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

wound  in  any  part  of  the  body  as  great  as  that  made  in  the  extraction 
of  a  tooth  will  cause  considerable  pain,  and  the  mouth  will  be  no  excep- 
tion. Usually  pain  from  simple  extractions  will  not  endure  for  any 
great  length  of  time.  There  are  several  conditions  that  will  bring 
about  post-operative  pain: 

1.  Extensive  traumatism  which  results  in  alveolitis. 

2.  Infection  either  present  at  the  time  of  the  operation  or  following 
the  operation. 

3.  A  fractured  root  with  a  portion  of  the  pulp  exposed  that  was  not 
removed. 

4.  Lack  of  normal  blood  supply  to  the  parts,  which  results  in  the 
formation  of  the  so-called  dry  socket. 

In  the  first  and  second  instances,  the  treatment  should  be  instituted 
as  indicated  above  for  alveolitis.  In  the  third  instance  all  particles 
of  the  tooth  root  should  be  removed  even  though  greater  traumatism  is 
produced.  In  the  fourth  instance  where  there  is  a  dry  socket  formed, 
a  curettage  of  the  tooth  socket  is  indicated  and  an  effort  made  to  pro- 
mote a  flow  of  blood  so  that  a  clot  may  be  formed  in  the  tooth  socket, 
and  the  normal  process  of  repair  permitted  to  proceed.  In  all  cases 
of  untoward  sequelae  following  the  operation  of  extraction  of  teeth, 
the  patient  should  be  kept  under  observation  by  the  operator  until 
normal  conditions  have  become  reestablished. 

Remedies  for  post-operative  pain  following  extraction  are  given 
under  "Post-Operative  Treatment  for  Impacted  and  Unerupted 
Teeth." 

IMPACTED  AND  UNERUPTED  TEETH. 

The  Impacted  Lower  Third  Molar. — ^This  condition  is  in  a  large  per- 
centage of  cases  caused  either  by  lack  of  normal  development,  or  by 
arrested  development  of  the  inferior  maxilla.  The  second  rnolar 
immediately  in  front  and  the  coronoid  process  behind  bound  the  space 
allotted  to  the  third  molar.  Each  tooth  which  has  no  deciduous 
predecessor  is  developed  beneath  the  base  of  the  coronoid  process. 
This  is  true  of  the  first,  second,  and  third  permanent  molars.  The 
only  manner  in  which  these  teeth  are  able  to  take  their  places  in  the 
normal  arrangement  of  the  teeth  in  the  jaw  is  by  the  physiologic 
resorption  of  the  anterior  surface  of  the  coronoid  process.  While  this 
process  of  resorption  is  going  on,  on  the  anterior  surface  of  the  coronoid 
process,  through  the  laws  of  compensation,  nature  has  provided  for  a 
deposition  of  bone  on  the  posterior  surface  of  the  condyloid  process. 
Through  these  two  physiologic  processes,  resorption  and  deposition  of 
bone  respectively,  all  of  the  molars  are  able  to  erupt  into  their  proper 


IMPACTED  AND   UNERUPTKI)   TEF/ril 


031 


positions.     Figs.  498,  499  and  500  show  (le\cloi)ineiitHl  stages  of  first, 
second,  and  third  molars. 


Fig.  498 


Fig.  499 


632     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

However,  when  either  or  both  of  these  physiologic  phenomena  in  the 
process  of  development  of  the  mandible  are  arrested,  the  interval 
between  the  anterior  surface  of  the  coronoid  process  and  the  last 
erupted  tooth  which  is  usually  the  second  molar,  will  be  insufficient  for 
the  normal  arrangement  of  the  presenting  third  molar.  Under  these 
conditions,  the  tooth  in  pressing  forward,  takes  a  direction  in  which 
the  least  resistance  to  its  progress  is  offered  and  a  condition  becomes 
manifest  which  is  termed  impaction. 


Fig.  500 


Another  condition  which  must  be  recognized  in  accounting  for  the 
mal-position  caused  by  the  impaction,  is  that  the  tooth  has  been  directed 
from  its  course  at  a  comparatively  early  period  of  development,  irrespec- 
tive of  resistance  offered  at  the  time  of  eruption.  This  condition  may 
be  accounted  for  by  a  change  in  the  character  of  the  cancellous  bone 
immediately  adjacent  to  the  developing  tooth.  If,  through  some 
inflammatory  process,  peculiar  to  the  individual,  or  by  the  same  process 
set  up  through  some  pathologic  disturbance,  or  trauma,  a  secondary 
deposit  of  dense  bone  is  laid  dowU;  around  the  developing  tooth,  a 


IMPACTED   AND    UNERUPTED   TEETlf  O-W 

change  in  the  (hrection  of  ernption  of  the  tooth  may  take  ])lace  or  tliere 
may  be  a  prevention  of  its  eruption.  This  retarded  condition  is  also 
due  to  the  fact  that  at  the  points  where  all  of  the  other  teeth  are 
located,  soft  spongy  bone  or  alveolar  process  is  found  and  resor])ti()n 
of  tissue  takes  place  more  readily  at  these  points  than  at  the  points  of 
eruption  of  the  third  molars  which  is  made  up  of  dense  cortical  or  true 
bone.  Frequently  the  third  molar  will  erupt  u?itil  it  comes  in  contact 
with  the  second  and  then  stop  on  account  of  insufficient  space,  in  which 
case  only  a  small  part  of  the  tooth  will  be  presented.  An  upper  third 
molar  presents  an  entirely  different  condition  on  account  of  the  dif- 
ference in  the  character  of  the  bones  in  the  superior  and  inferior  maxillae. 
When,  for  any  reason  there  is  a  retarded  development  of  the  superior 
maxilla  which  makes  it  shorter  in  its  anterior  posterior  diameter,  so 
that  there  is  not  sufficient  room  for  the  normal  eruption  of  the  third 
molar,  the  crown  of  this  tooth  will  point  toward  the  cheek,  taking  the 
direction  of  least  resistance  in  its  course.  It  slides  out  to  the  side,  being 
guided  by  the  second  molar,  which  is  already  in  place.  If  there  were 
sufficient  room,  both  upper  and  lower  third  molars  would  erupt  without 
pain,  but  this  is  rarely  the  case. 

The  cuspids  are  the  next  in  the  series  most  likely  to  be  impacted. 
The  etiology  of  this  condition  is  the  same  as  that  of  the  impacted  molars, 
namely,  insufficient  spaces  for  the  normal  presentation  of  the  teeth 
in  the  process  of  eruption.  The  cuspid  teeth  make  their  appearance 
long  after  the  eruption  of  the  lateral  incisors  and  sometime  after  the 
eruption  of  the  first  bicuspids.  In  case  of  retarded  development  of 
the  maxillse,  there  may  not  be  sufficient  room  between  the  lateral 
incisors  and  first  bicuspids  for  normal  eruption  of  the  cuspids  and  as  a 
result  impaction  occurs. 

On  account  of  the  tendency  of  erupting  teeth  to  follow  the  course  of 
least  resistance,  they  will  slide  out  to  the  buccal  or  into  the  lingual 
surfaces  of  the  maxillse.  It  is  also  true  that  at  an  early  period  of 
development  of  these  teeth,  a  secondary  deposit  of  bone  in  the  maxillse, 
due  to  an  inflammatory  process,  may  influence  a  change  of  direction 
in  the  developing  teeth  so  as  to  change  their  position  entuely  when  they 
erupt. 

While  the  thu-d  molars  and  cuspids  are  predisposed  to  impaction 
more  frequently  than  any  others,  yet  any  tooth  in  either  maxilla  may 
become  impacted  if  the  environment  is  not  such  that  normal  eruption 
can  be  made  possible. 

The  next  anomaly  which  may  be  considered  is  the  unerupted  or 
aberrant  tooth.  This  condition  may  be  present  in  any  part  of  either 
maxilla  and  any  tooth  may  be  the  offending  member. 

There  is  alwa}^s  a  reason  for  such  teeth  being  unable  to  erupt  norm- 


634    EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

ally.  The  developing  teeth  meet  some  obstruction  in  their  normal 
course,  such  as  supernumerary  teeth  or  normal  teeth  which  have 
previously  erupted  and  already  occupy  the  space  belonging  to  the 
erupting  teeth.  Again,  a  previous  inflammatory  condition  in  the 
cancellous  bone  may  have  set  up  secondary  deposits  of  dense  bone 
which  will  prove  an  obstruction  to  the  developing  teeth  and  deflect 
them  out  of  normal  alignment. 

Pathologic  Possibihties. — Some  of  the  pathologic  conditions  which 
are  induced  by  these  dental  anomalies  will  now  be  considered.  The 
impacted  lower  third  molars  will  be  taken  up  first. 

Perhaps  the  most  common  disturbance  to  be  encountered  is  local 
infection  of  the  soft  tissues  surrounding  the  teeth.  This  condition  is 
usually  present  in  the  partially  erupted  teeth  when  the  gum  tissue 
which  should  occupy  the  space  between  the  anterior  surface  of  the 
coronoid  process  and  third  molar  has  been  forced  out  over  the  disto- 
occlusal  surface  of  the  tooth  and  becomes  contused  in  mastication. 
Bacteria-laden  saliva  and  food  particles  are  forced  into  the  interstice 
between  the  tooth,  and  swollen  tissue  and  infection  take  place.  Inflam- . 
mation  is  set  up  and  maintained,  which  is  not  limited  to  the  injured 
parts,  but  more  commonly  extends  to  the  adjacent  structures  involving 
the  soft  textures  about  the  ascending  ramus  and  frequently  involving 
the  paratonsilar  region. 

Deglutition  becomes  painful  and  trismus  is  set  up.  Many  times  the 
patient  is  imable  to  open  the  jaws  more  than  two  or  three  millimeters. 
After  a  time  suppuration  takes  place  and  the  movements  of  the  jaws 
become  less  constrained. 

In  these  acute  conditions  immediate  surgical  procedure  is  contra- 
indicated.  The  treatment  indicated  is  to  apply  counter-irritants,  the 
application  of  cold  compresses  or  ice  to  the  face,  and  to  have  all  of  the 
body  eliminating  processes  active. 

After  the  inflammation  has  subsided  and  the  jaws  have  become  less 
constrained,  conditions  should  be  restored  to  normal  by  surgical  pro- 
cedure to  obviate  repeated  attacks.  This  condition  will  rarely  be  found 
around  other  impacted  teeth  than  the  lower  third  molars. 

A  pathologic  condition  which  may  occur  as  a  result  of  an  impacted 
tooth  is  pressure  resorption.  When  the  crown  of  one  of  these  teeth  is 
lodged  or  impacted  against  the  root  of  an  adjacent  tooth,  the  hard 
enamel  surface  of  the  impacted  tooth  will  cause  a  resorption  of  the 
tissues  of  lesser  resistance  of  the  other  one.  This  may  go  on  to  such  an 
extent  that  the  pulp  of  the  adjacent  tooth  will  be  encroached  upon. 

A  very  serious  condition  may  arise  from  an  impacted  lower  third 
molar  by  pressure  being  exerted  upon  the  inferior  dental  nerve.  The 
position  of  this  tooth  in  the  maxilla  predisposes  to  impingement  upon 


IMPACTED  AND   UNERUPTEl)   TEKTII  035 

the  inferior  dental  canal.  In  such  cases  a  reflected  ])aiii  may  be  set 
up  which  will  be  expressed  in  any  part  of  the  liead  wliicli  lias  its 
sensory  nerve  supply  from  the  fifth  or  trigiminal  nerve. 

Neuralgia  may  have  its  etiology  in  such  conditions.  The  late 
Dr.  Henry  S.  Upson,  former  professor  of  Neurology  in  the  Western 
Reserve  University,  ascribed  many  of  the  nervous  disorders  which 
"mankind  is  heir  to"  to  impacted  teeth.  He  stated  that  "certain 
types  of  nervous  disturbances  caused  by  dental  impactions  have  almost 
the  clearness  of  a  laboratory  experiment,  as  in  them  the  severest 
symptoms  are  set  up  by  the  simplest  irritant.  Pain  may  be  from  the 
beginning  to  the  end  quite  lacking."  It  is  the  constant  though  mild 
irritation,  perhaps  not  sufficient  to  produce  pain,  that  sets  up  some  of 
these  nervous  disturbances  which  may  of  themselves  take  on  a  \'iolent 
form. 

Alopecia  areata,  or  baldness  occurring  in  sharply  defined  patches, 
leaving  the  scalp  smooth  and  white,  is  a  condition  due  to  a  nervous 
disturbance.  An  impacted  tooth  must  be  considered  an  etiological 
factor  in  this  affection. 

During  the  last  few  years,  the  author  has  had  several  cases  of  this 
nature  that  showed  marked  improvement  after  the  removal  of  impacted 
teeth. 

Another  abnormal  condition  that  is  quite  frequently  found  associated 
with  the  presence  of  impacted  lower  third  molars  is  a  tendency  for 
these  teeth  in  their  effort  to  erupt  to  force  all  of  the  lower  teeth  forward. 
Orthodontists  have  found  it  almost  impossible  to  retain  normal  occlu- 
sion following  orthodontic  treatment  with  these  teeth  present  in  the 
jaws.  Many  fine  orthodontic  results  have  been  ruined  by  the  presence 
and  activity  of  impacted  teeth. 

What  are  the  pathologic  possibilities  of  unerupted  teeth?  It  is  a 
remarkable  fact,  and  one  which  has  not  been  fully  explained,  that 
unerupted  teeth  having  lain  dormant  for  years  in  the  jaws  suddenly 
become  the  seat  of  purulent  inflammation  wdth  sometimes  serious 
symptoms.  Such  cases  are  by  no  means  rare.  Some  lATiters  are  of  the 
opinion  that  under  certain  conditions  such  teeth  may  act  as  foreign 
bodies  and  may  even  fall  prey  to  resorption.  Under  these  conditions 
where  an  irritation  has  been  set  up  and  piuulent  inflammation  has 
become  seated,  a  bone  abscess  may  form  around  the  region  of  an 
unerupted  tooth.  This  abscess  may  develop  until  a  large  portion  of  the 
maxilla  becomes  involved. 

Another  condition  which  is  seen  frequently  in  the  mouths  of  men 
and  women  under  thirty  years,  is  the  cystic  growths  connected  with 
these  teeth  whose  eruption  is  retarded.  In  the  light  of  our  present 
knowledge  the  explanation  for  the  formation  of  these  cysts  is  largely 


636     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

theoretical.  Tomes  has  suggested  the  most  plausible  theory.  He 
states  that  when  the  development  of  the  enamel  of  a  tooth  is  com- 
pleted, its  outer  surface  becomes  perfectly  detached  from  the  investing 
soft  tissue  and  a  small  quantity  of  transparent  fluid  not  uncommonly 
collects  in  the  interval  so  formed.  This  fluid  ordinarily  is  discharged 
when  the  tooth  is  erupted,  but  when  from  some  cause  the  eruption  of 
the  tooth  is  prevented,  it  increases  in  quantity  and  gradually  distends 
the  surrounding  tissues,  causing  a  resorption  and  disintegration  of  the 
osseous  structures.  These  cysts  may  go  on  developing  until  a  large 
portion  of  the  maxilla  is  involved. 

Again,  an  unerupted  tooth  may,  by  coming  in  contact  with  the  roots 
of  the  normal  erupted  teeth,  cause  pressure  resorption  and  thus  produce 
a  permanent  injury  to  them.  When  this  tooth  lies  in  close  proximity 
to  a  nerve  trunk,  it  may  cause  undue  pressure  and  set  up  the  same 
obscure  nervous  disturbances  which  have  been  attributed  to  impacted 
teeth. 

Treatment.^ — ^We  have  considered  briefly  the  etiology  and  pathology 
of  some  of  these  dental  anomalies.    We  will  now  consider  the  treatment. 

An  unerupted  tooth  should  be  removed  when  it  is  suspected  of  any 
disturbance.  Successful  diagnosis  is  made  only  by  a  process  of 
elimination  and  when  such  a  tooth  is  present  in  the  jaws  and  the  patient 
is  suffering  from  obscure  nervous  disturbance,  the  removal  of  it  is 
indicated  in  order  to  eliminate  a  possible  source  of  trouble.  Its 
removal,  together  with  the  entire  cystic  lining  must  be  accomplished 
in  cases  of  dental  cysts.  This  should  not  be  attempted  without  a 
good  roentgenogram,  which  should  point  out  the  location  of  the  tooth 
and  the  dimensions  of  the  cyst. 

In  fact,  the  removal  of  any  unerupted  tooth  should  not  be  attempted 
without  a  good  roentgenogram  for  the  reason  that  any  unnecessary 
cutting  or  laceration  of  the  tissues  is  not  permissible  in  these  operations. 
In  the  removal  of  these  teeth  the  author  prefers  to  uncover  them  by 
means  of  a  chisel  and  mallet,  thus  the  landmarks  are  not  destroyed 
which  otherwise  might  be  the  case  in  the  use  of  the  bur  and  engine. 
After  the  location  of  the  tooth  and  the  character  of  its  environment 
have  been  determined,  the  use  of  the  bur  or  drill  is  permissible  in  the 
further  removal  of  the  osseous  tissues  and  in  the  dislodgment  of  the 
tooth. 

In  the  removal  of  an  impacted  tooth  other  than  the  lower  third 
molar,  no  definite  technic  can  be  followed  since  each  case  will  usually 
present  entirely  different  conditions. 

In  the  removal  of  the  impacted  lower  third  molar,  however,  the 
author  believes  that  it  is  possible  to  follow  a  definite  technic  in  prac- 
tically every  case.     In  other  words,  the  operator  should  have  a  clear 


IMPACTED  AND   UN  ERUPT  ED   TEETH  637 

conception  of  the  whole  situation  and  know  exactly  what  has  to  be 
accomplished  in  order  to  remove  the  tooth  with  the  least  amount  of 
traumatism.  In  a  large  percentage  of  cases  no  more  traumatic  injuries 
should  be  made  upon  the  osseous  tissue  than  in  the  extraction  of  the 
first  or  second  molars. 

The  difference  in  the  character  of  the  process  of  repair  of  the  two 
wounds  is  due  largely  to  the  extent  of  the  pre-operative  inflammatory 
process  present,  which  is  usually  very  much  greater  in  the  case  of  an 
impacted  molar. 

Technic  for  Removal  of  Impacted  Lower  Third  Molars. — After  the  field 
of  operation  has  been  sterilized  of  its  gross  sepsis  and  anesthetized,  an 
incision  1  centimeter  long  is  made  through  the  soft  tissues  over  the 
tooth.  Then  a  vertical  incision  is  made  about  2  millimeters  distal 
to  the  second  molar  and  extended  to  a  point  half  way  between  the 
gingival  margin  and  the  root  of  the  second  molar  (Fig.  501).  The 
triangular  flap  is  then  raised,  exposing  the  osseous  tissue  surrounding 
the  tooth  (Fig.  502). 

The  next  step  is  to  remove  by  the  chisel  and  mallet  a  section  of  the 
process  overljdng  the  tooth  to  an  extent  that  there  will  be  sufficient 
space  between  the  second  molar  and  the  osseous  structure  covering 
the  tooth  to  permit  it  to  be  displaced  (Fig.  503).  A  surgical  drill  is 
then  used  to  remove  a  section  of  the  cortical  bone  2  mm.  in  mdth 
contiguous  to  the  buccal  surface  of  the  tooth  (Fig.  504).  The  wedge 
of  cancellous  bone  between  this  surface  and  the  tooth  socket  is  readily 
removed  with  the  chisel.  Then  the  chisel  is  driven  between  the 
buccal  surface  of  the  tooth  and  buccal  plate  of  the  alveolar  process 
mth  the  bevel  of  the  chisel  next  to  the  buccal  plate,  and  by  a  prying 
motion  the  buccal  and  lingual  plates  are  sprung  apart  sufficiently  to 
loosen  the  tooth  (Fig.  505) .  Fig.  506  is  a  cross-section  of  an  impacted 
third  molar,  showing  the  thin  lingual  plate.  Then,  by  means  of  an 
elevator  (preferably  the  Lecluse)  the  tooth  is  rotated  backward  and 
out  (Figs.  507  and  508).  At  the  stage  in  the  operation  necessitating 
the  use  of  the  elevator,  the  chisel  may  be  used  as  an  elevator  and  the 
tooth  removed.  The  elevator  should  never  be  used  until  the  tooth  is 
seen  to  rotate  slightly  in  its  socket  under  the  stress  of  the  chisel.  Until 
this  time,  the  impaction  has  not  been  relieved,  and  any  attempt  to 
use  the  elevator  might  result  in  fracture  of  the  tooth  or  of  the  alveolar 
process,  or  even  of  the  mandible. 

The  same  principle  is  followed  with  any  degree  of  impaction  and 
also  with  a  tooth  that  is  not  only  impacted  but  unerupted  as  well. 
The  cutting  should  all  be  done  from  the  buccal  siu"face,  as  there  are  no 
vulnerable  tissues  at  this  point,  while  on  the  lingual  siuface  the  lingual 
nerve  and  artery  might  be  injm"ed  if  much  cutting  were  attempted. 


638    EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

Under  novocain  anesthesia  there  is  very  little  hemorrhage  and  this  is 
controlled  by  a  gauze  sponge  inserted  on  the  buccal  surface  adjacent 


Fig.  501 


Fig,  502 


to  the  operative  field.  There  is  one  point  for  the  operator  to  keep  in 
mind  and  that  is  that  the  impacted  tooth  is  wedged  into  the  jaw  and 
the  impaction  has  to  be  relieved  before  the  tooth  can  be  removed. 


IMPACTED  AND   UNERUPTED  TEETH 


639 


This  may  be  done  with  burs,  drills,  stones,  cutting  forceps  or  chisels. 
The  wound  made  from  the  chisel  is  a  clean  sharp  one  and  not  rough 


Fig.  503 


Fig.  504 


and  ragged  such  as  those  made  by  burs.  Conseciuently  repair  will 
take  place  around  a  wound  made  with  a  chisel  much  more  quickly 
than  if  the  tissues  are  lacerated  by  burs. 


640     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

Post-operative  Treatment. — ^The  procedure  which  has  been  very 
satisfactory  in  the  author's  hands  is  to  saturate  plain  or  iodoform 
gauze  with  euroform  paste  and  pack  the  socket  with  it  for  twenty-four 
hours  immediately  after  the  operation.     This  preparation  is  antiseptic 


Fig.  505 


and  its  sedative  action  is  most  beneficial.  At  the  end  of  twenty-four 
hours  the  dressing  is  removed  and  the  patient  instructed  to  use  a  warm 
5  per  cent,  salt  solution  as  a  mouth  wash.  Dentalone  on  absorbent 
cotton  rolls  inserted  into  the  socket  may  be  used  to  advantage. 


F 

^ 

1 

/ 

U 

^^S 

*l 

H 

¥ 

b.  '.  ,^ 

^ 

Fig.  506 


The  wound  should  be  kept  free  from  all  food  deposits  and  debris 
by  the  use  of  sprays  of  5  per  cent,  salt  solution,  until  repair  takes  place. 
No  curettage  is  necessary  in  these  cases  unless  an  abscessed  condition 


IMPACTED  AND   UNERUPTED   TEETH 


641 


is  present,  in  which  case  curettage  of  the  socket  is  indicated.  In  cases 
of  post-operative  pain,  asperin  15  grains  may  be  given  as  a  nerve 
sedative.     Pyramidon  in  5-grain  doses  acts  as  an  antip\Tetic  and  an 


Fig.  507 


Fig.  508 


analgesic  and  will  yield  good  results.  Dusting  of  anesthetic  powder 
such  as  novocain  powder,  novoesthene  or  parathesen  into  the  socket 
will  be  an  aid  incontrolling  post-operative  pain. 

41  . 


642     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

A  thorough  knowledge  of  the  pathologic  possibilities  of  these  dental 
anomalies,  a  definite  technic  for  their  elimination,  and  a  scientific 
treatment  for  pre-operative  and  post-operative  conditions  are  all 
essential  for  success.  The  personal  ability  of  the  operator  will  be  the 
predominating  factor  in  the  success  or  failure  in  their  diagnosis  and 
treatment. 


Fig.  509 


External  Alveolectomy.^ — In  cases  of  prognathism  it  is  sometimes 
very  desirable  to  remove  the  external  alveolar  plate  in  either  the  upper 
or  lower  jaws,  or  both,  following  the  operation  for  the  extraction  of 
teeth.  By  so  doing,  a  more  efficient  denture  can  be  obtained.  This 
operation  can  be  done  either  under  local  or  general  anesthesia,  and 
should  be  done  immediately  following  the  operation  for  the  extraction 
of  teeth  when  indicated.    Fig.  509  shows  a  case  in  which  such  an 

1  The  author  is  indebted  to  Dr.  Wm.  L.  Shearer,  of  Omaha,  Nebraska,  for  the  valuable 
illustrations  in  the  external  alveolectomy  and  the  modified  external  alveolectomy. 


IMPACTED  AND   UNERUPTED   TEETH 


643 


operation  is  indicated.  After  the  extraction  of  the  teeth  the  muco- 
periosteum  is  reflected  back  by  means  of  a  flat  periosteal  ele\'ator 
to  a  point  opposite  the  apices  of  the  tooth  sockets.  This  is  shown  in 
Fig.  510.  Then  by  Rongeur  forceps  (Fig.  511)  the  external  plate  of  the 
alveolar  process  is  entirely  removed.  At  the  same  time  the  border  of 
the  internal  plate  is  made  straight  and  smooth  (Fig.  512).  Following 
this,  the  internal  and  external  margins  of  the  periosteal  flaps  are 
trimmed  so  that  even  margins  are  obtained.  The  flaps  are  then 
brought  together  and  sutured,  bringing  the  outer  and  inner  muco- 
periosteal  flaps  into  normal  position  over  the  exposed  bone,  as  illus- 
trated in  Fig.  513.     The  sutures  should  be  left  in  for  a  period  of 


Fig.  510 

about  eight  days.  This  operation  can  be  used  advantageously  in  any 
case  following  extraction  of  all  the  teeth.  The  operator  can  so  shape 
the  ridge  of  the  mouth  as  to  make  an  artificial  denture  more  efficient. 
Modified  External  Alveolectomy.— INIodification  of  the  operation  of 
external  alveolectomy  may  be  made  successfully  in  cases  where  exten- 
sive curettage  is  indicated.  Fig.  51-1  illustrates  a  case  where  the  buccal 
plate  of  the  alveolar  process  is  involved  through  to  the  muco-perios- 
teum.  Such  a  case  usually  represents  an  infectious  process  of  long 
standing,  or  what  is  termed  chronic  dento-alveolar  abscess.  In  some 
of  these  cases  by  raising  the  muco-periosteal  flap,  as  illustrated,  the 
granuloma  will  be  raised  with  the  flap  and  it  is  sometimes  ^•ery  adherent 


J 


V. 


Fig.  511 


IMPACTED  AND   UNERUPTEf)   TEF/rif 


645 


«l»s^^ 

il 

w/ 

l^^ 

WW 

aT^ 

1 

FiG.'512 


Fig.  513 


Fig.  514 


Fig.  515 


646    EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

by  a  tough  fibrous  tissue  attachment.  After  raismg  the  muco-periosteal 
flap,  all  diseased  areas  should  be  curetted  thoroughly  as  shown  in  Fig. 

515.  This  procedure  is  of  advantage  to  the  operator  since  he  can  see 
when  he  has  curetted  down  to  healthy  tissue.  The  muco-periosteal 
flap  is  then  returned  to  normal  position  and  sutured  as  shoT\Ti  in  Fig. 

516.  These  sutures  should  be  removed  after  six  or  eight  days. 


,  ^ 

J^ 

Ipip^^    /- 

-^_ 

¥i 

^^k 

1 

I 

Clte^ 

1 

\ 

Im 

^^c>^ 

iH^rC'' 

^p^ 

1  nS&^fitf 

/ 

Mm: 

1 

1 

^/f' 

4' 

■  \  - 

1 

Fig.  516 


The  post-operative  treatment  for  both  the  external  alveolectomy, 
and  the  modified  external  alveolectomy  consists  of  keeping  the  sm"faces 
absolutely  clean  with  sprays  of  5  per  cent,  salt  solution  and  painting 
the  surfaces  with  20  per  cent,  solution  of  argyrol. 

Apicoectomy. — The  author  has  previously  referred  to  apicoectomy  as 
a  means  of  eradicating  infection  aromid  certain  teeth.  It  has  seemed 
advisable  to  treat  this  subject  followdng  that  of  extraction  of  teeth. 

Indication  and  Contra-indication  for  Apicoectomy. — ^For  many  years 
ends  of  roots  of  teeth  have  been  excised  under  the  names  of  root 
amputation,  root  excision,  maxillotomy,  apiectomy,  apicoectomy, 
and  root  resection.     As  early  as  1884  the  technic  of  the  operation  was 


IMPACTED  AND   UNERUPTED  TEETH  647 

described  by  Farrar.  Many  writers  since  that  time  have  written  on 
one  phase  or  another  of  the  subject  until  today  it  would  seem  that 
this  is  an  operation  that  should  become  an  important  one  in  every  well 
conducted  dental  practice. 

Dental  and  medical  science  have  made  it  clear  that  pathologic 
conditions  of  the  pericemental  membrane  and  diseased  ends  of  the 
roots  of  the  teeth  are  a  contributing  factor  to,  and  frequently  the 
primary  cause  of,  general  systemic  distiu-bances.  Dentistry  must 
now  assume  the  tremendous  responsibility  of  eliminating  these  morbid 
conditions,  either  by  the  extraction  of  the  teeth  followed  by  a  curettage 
or  by  some  other  surgical  or  therapeutic  procedure. 

It  is  a  well  known  fact  that  with  the  present  methods  of  root  canal 
therapy  few  of  these  morbid  conditions  can  be  eliminated.  Assimiing 
then  that  our  deductions  are  correct,  there  is  only  one  course  left  open, 
namely,  surgical  procedure. 

The  surgical  procedure  can  be  accomplished  in  one  of  two  ways — 
either  by  the  extraction  of  the  tooth  and  ciu*ettage,  or  by  opening 
through  the  alveolar  process,  excising  the  diseased  root  end,  and 
thoroughly  curetting  the  diseased  area. 

The  question  now  arises,  how  are  we  to  make  a  correct  diagnosis  of 
the  case  so  as  to  govern  our  surgical  procedure? 

No  hard  and  fast  lines  can  be  drawn  as  to  just  where  apicoectomy  is 
indicated  and  w^here  extraction  of  the  tooth  should  be  the  operation 
of  choice. 

Apicoectomy  is  by  no  means  a  "cure  all"  for  all  conditions  of 
chronic  alveolar  abscess  when  medicinal  therapy  has  failed.  Indeed 
it  is  the  opinion  of  the  author  that  in  many  of  these  cases  the  patient's 
welfare  will  be  better  taken  care  of  if  extraction  of  the  tooth  followed 
by  curettage  is  resorted  to. 

What  then  are  to  be  the  signs  and  symptoms  which  mil  govern  in 
the  selection  of  the  operation  that  is  indicated? 

A  correct  diagnosis  of  each  case  is  not  at  all  a  simple  matter.  The 
first  thing  to  take  into  consideration  is  the  present  state  of  health, 
past  illness,  and  the  possible  recuperative  or  reserve  force  of  the 
patient.  The  lowering  of  the  vitality  through  chronic  alcoholism  or 
such  diseases  as  tuberculosis,  s^q^hilis,  and  diabetes  which  lead  to  a 
state  of  constitutional  dyscrasia  will  have  a  profound  influence  in 
preventing  repair  after  these  operations.  In  such  cases  the  operation 
of  choice  in  eliminating  the  pathologic  conditions  around  root  ends  is 
extraction  of  the  offending  tooth  followed  by  thorough  curettage  of 
the  bone.  Age  may  be  a  factor  which  should  be  considered  in  deter- 
mining the  indications  and  contra-indications  for  apicoectomy.  In  the 
aged  the  process  of  repair  is  slow  and  the  prognosis  for  bone  repair  is 


648    EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

not  so  good  as  in  the  young  or  in  the  middle-aged.  In  a  patient  of 
advanced  years  it  would  be  a  question  whether  the  cavity  following 
this  operation  would  be  filled  in  with  normal  tissue.  Particularly  would 
this  be  true  if  there  were  much  involvement  of  the  apical  area,  conse- 
quently the  operation  would  be  undertaken  with  considerable  hazard. 

The  normal  or  abnormal  circulation  of  the  blood  is  another  factor 
that  plays  a  very  important  role  in  the  success  or  failure  of  the  opera- 
tion. It  is  an  established  surgical  fact  that  without  a  certain  definite 
blood  supply  to  a  part,  repair  of  tissue  will  not  take  place.  Notwith- 
standing the  fact  that  the  teeth  and  surrounding  tissues  have  a  very 
rich  blood  supply,  in  certain  types  of  individuals  and  under  certain 
pathologic  disturbances  such  as  in  the  anemic  and  poorly  nourished, 
there  is  not  sufficient  blood  supply  to  the  apical  area  to  insure  repair 
of  the  parts  after  the  operation.  This  condition  is  found  in  the  young 
as  well  as  in  the  aged,  and  the  clever  diagnostician  will  discover  it 
before  making  his  decision  as  to  whether  apicoectomy  or  extraction 
is  indicated. 

It  is  unfortunate  that  many  men  are  depending  entirely  upon  the 
roentgenogram  in  diagnosing  mouth  infection  and  are  governing  their 
whole  course  of  treatment  on  this  knowledge  alone.  They  seem  to 
overlook  the  fact  that  the  roentgenogram  is  merely  the  shadow  of 
conditions  in  the  bone  and  does  not  show  a  picture  of  the  pathology 
involving  the  parts. 

In  making  the  diagnosis  which  will  lead  to  an  operation  such  as 
apicoectomy,  the  roentgenogram  must  be  used  as  only  one  of  our 
means  of  forming  our  conclusions.  The  roentgenogram  may  show  the 
appearance  of  greater  pathology  than  is  actually  present  and  again 
the  tooth  root  may  be  interposed  between  the  ray  and  the  morbid 
area  in  such  a  way  that  it  may  appear  that  little  or  no  pathology  is 
present;  therefore  the  extent  of  the  pathologic  involvement  that  will 
appear  to  be  present  will  depend  upon  the  angle  from  which  the  roent- 
genogram is  taken.  This  you  will  readily  conceive  is  not  sufficiently 
definite  to  rely  upon  wholly  in  forming  a  judicious  and  conservative 
diagnosis.  The  roentgenogram  then  should  be  considered  only  one 
link  in  the  chain  of  evidence  upon  which  we  must  base  our  decision. 
Then  again,  there  may  have  been  some  involvement  and  rarefaction 
of  the  tissues  before  therapeutic  measures  were  resorted  to,  which  the 
patient's  natural  power  of  immunity  and  resistance  will  clear  up  after 
the  infection  has  been  eliminated  from  the  canal  and  tubuli  of  the 
tooth. 

If  we  can  be  satisfied  that  the  end  of  the  root  is  not  denuded  of  its 
pericemental  membrane,  then,  in  the  author's  opinion,  the  case  may  be 
watched  and  a  series  of  roentgenograms  taken  at  stated  intervals  and 


IMPACTED  AND   UNERUPTED  TEETH  649 

compared.  The  patient  should  be  apprised  of  the  fact  that  this  par- 
ticular tooth  is  under  suspicion.  Here  again  the  general  state  of  health 
of  the  patient  must  be  considered,  and  the  technic  of  sterilizing  and 
filling  the  root  canal  must  be  a  part  of  the  chain  of  evidence  which 
governs  our  procedure. 

If  the  case  be  an  alveolar  abscess  of  long  standing  or  an  imperfectly 
filled  root  canal  with  granuloma  where  all  the  evidence  points  to  dis- 
ease and  death  of  the  pericemental  membrane  in  the  apical  area,  it  is 
the  opinion  of  the  author  that  surgical  procedure  rather  than  dental 
therapy  is  indicated. 

The  character  of  the  surgical  procedure  may  be  apicoectomy  in 
favorable  teeth  and  extraction  of  the  teeth  in  unfavorable  cases. 
What  are  to  be  considered  favorable  cases  for  apicoectomy? 

The  operation  is  often  done  with  the  view  of  saving  a  nice  piece  of 
bridge  work  and  no  attempt  is  made  to  eliminate  the  source  of  the 
infection.  It  should  be  a  matter  of  routine  that  the  canals  and  tubuli 
be  sterilized  and  filled  just  previous  to  the  operation.  We  are  not  doing 
good  surgery  when  this  is  not  done. 

The  most  favorable  teeth  for  this  operation  are  single  rooted  teeth. 
This  limitation  has  been  made  for  two  reasons.  First,  because  of  the 
accessibility  of  these  teeth,  a  clean  surgical  operation  can  be  performed. 
Second,  sterilization  and  filling  of  the  root  canals  can  be  made  more 
accurate. 

In  multi-rooted  teeth  the  patient's  welfare  will  be  better  taken  care 
of  by  extraction  of  the  tooth  followed  by  curettage  of  the  bone.  In  no 
case  should  this  operation  be  resorted  to  when  the  tissues  are  diseased 
beyond  the  apical  third  of  the  root  of  the  tooth. 

The  success  of  the  operation  will  depend  upon  whether  or  not  the 
diagnosis  has  been  correct.  The  welfare  of  the  patient  should  be  the 
first  consideration  and  a  hasty  diagnosis  may  lead  to  an  operation 
rather  than  a  successful  treatment  of  the  condition. 

Surgical  Technic  of  Apicoectomy. — ^The  foundation  upon  which  the 
success  or  failure  of  this  operation  rests,  is  the  condition  of  the  root 
canals  and  tubuli,  and  the  extent  of  pathologic  involvement.  It  is 
imperative  that  the  canals  and  tubuli  be  sterilized  and  the  canals  filled 
just  preceding  the  operation.  The  possibilities^  of  reduced  silver  in  the 
preparation  of  roots  for  resections,  seem  most  encouraging. 

The  silver  solution  used  for  rapid  reduction  is  made  up  as  follows: 
silver  oxid  is  precipitated  from  a  silver  nitrate  solution  with  KOH  or 
NaOH.  This  is  carefully  washed  to  remove  all  impm-ities  and  kept 
moist  in  a  small  amber-colored  bottle.     In  this  condition  reduction  is 

1  This  is  a  modification  of  a  method  advocated  by  Howe  for  silver  reduction. 


650     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

so  slight  that  it  can  be  kept  for  a  long  time  without  much  change. 
If  a  small  amount  is  insoluble  in  excess  of  ammonia,  there  has  been  too 
much  reduction  and  the  silver  oxid  should  be  freshly  prepared.  This 
is  the  stock  solution  and  it  will  be  seen  that  it  is  more  desirable  than 
the  ammoniacal  solution  made  from  silver  nitrate,  because  it  is  free 
from  nitric  acid  and  other  impurities. 

When  rapid  reduction  is  desired  as  for  apicoectomy,  the  silver  oxid 
is  added  to  a  drop  or  two  of  ammonium  hydroxid  to  the  point  of 
saturation.  This  forms  silver  ammonium  oxid.  In  this  state  the 
ammoniacal  solution  is  reduced  easily.  The  case  in  which  reduction 
takes  place  with  this  solution  is  so  marked  that  bm-nishing  with  a 
warm  glass  rod  is  sufficient  to  reduce  it  to  the  lustrous  metallic  silver. 
A  precaution  that  should  be  mentioned  is  that  after  a  few  hours,  ful- 
minates of  silver  may  be  formed  from  the  ammoniacal  solutions,  which 
are  very  explosive.  Serious  accidents  are  possible  from  even  wet 
solutions.  Only  very  small  amounts  of  ammoniacal  solutions  should 
be  made  and  the  unused  portion  discarded  immediately  after  treat- 
ment. After  complete  reduction  there  is  no  danger  and  only  old  ammo- 
niacal solutions,  especially  after  drying,  are  to  be  avoided. 

The  following  technic  is  the  one  used  preparatory  to  resection:  the 
canals  are  opened,  using  the  rubber  dam,  and  the  silver  solution  is 
introduced  to  the  very  apex.  Five  or  ten  minutes  are  allowed  for 
penetration  before  the  reducing  agent  is  applied.  This  treatment  is 
applied  several  times.  The  canals  are  then  very  carefully  filled  by 
packing  with  small  pieces  of  gutta-percha  points  softened  by  gently 
heating  or  other  acceptable  material. 

Assuming  now  that  the  root  canals  and  dental  tubuli  have  been 
sterilized  and  the  root  canals  properly  filled,  what  is  the  modus  operandi 
of  apicoectomy? 

In  the  first  place,  this  operation  consists  of  invading  the  soft  tissues 
as  well  as  the  alveolar  process,  and  a  recognition  of  the  difference 
between  surgical  and  dental  cleanliness  must  be  made.  If  this  opera- 
tion is  •  to  take  a  place  in  conservative  practice,  the  same  surgical 
asepsis  must  be  maintained  not  only  in  the  field  of  operation,  but  with 
the  operator  as  well,  as  would  be  necessary  in  any  surgical  work  in  the 
same  or  a  similar  field. 

Local  anesthesia,  either  conduction  or  infiltration,  is  the  anesthetic  of 
choice  for  this  operation  on  account  of  the  ability  to  secure  the  coopera- 
tion of  the  patient  and  to  control  the  hemorrhage.  These  are  factors 
not  to  be  ignored.  Clinical  experience  has  demonstrated  that  an 
isotonic  anesthetic  solution  if  properly  used  does  not  interfere  with  the 
process  of  repair. 

After  the  field  has  been  anesthetized,  the  first  step  in  the  operation 


IMPACTED  AND   UNERUPTED   TEETH  651 

is  to  remove  the  gross  sepsis  from  the  field  of  operation.  Tliis  is 
accompHshed  by  the  use  of  alcohol  to  dry  the  surface  over  the  field  of 
operation,  followed  by  swabbing  with  7  per  cent,  tincture  of  iodin. 

A  curved  incision  is  then  made  over  the  point  where  the  tooth  is  to 
be  resected,  about  2  centimeters  in  length  with  the  convexity  toward 
the  cervical  line.  The  incision  should  be  made  through  the  muco- 
periosteum  to  the  alveolar  plate.  The  muco-periosteum  is  then  raised 
by  blunt  periosteal  elevators  to  form  a  muco-periosteal  flap.  By  so 
doing,  the  outer  plate  of  the  alveolar  process  over  the  infected  area  is 
exposed.  In  some  cases  the  outer  plate  will  have  become  disintegrated 
so  that  the  raising  of  the  periosteal  flap  will  expose  the  apical  end  of  the 
tooth  root.  In  other  cases,  when  the  outer  plate  of  the  alveolar 
process  is  intact,  the  apical  end  of  the  tooth  root  may  be  exposed  by 
the  use  of  sharp  hand  chisels,  using  them  to  cut  away  the  outer  plate 
until  the  root  end  is  exposed.  The  author  prefers  the  chisels  for  expos- 
ing the  root  end  on  account  of  the  ability  to  preserve  the  landmarks 
during  the  entire  operation. 

A  sufficient  area  of  the  outer  plate  should  be  removed  so  that  the 
infected  crypt  and  the  apical  end  of  the  tooth  root  are  exposed.  The 
resection  of  the  apical  end  of  the  root  is  made  at  the  floor  of  the  crypt 
and  the  root  of  the  tooth  is  cut  down  to  healthy  tissue. 

The  Henahan  surgical  drill  No.  4  is  a  very  eflacient  instrument  for 
the  purpose  of  resecting  the  root.  The  resected  end  is  now  lifted  out 
of  the  crypt  and  the  pocket  thoroughly  curetted  with  spoon-shaped 
bone  curettes.  A  large  round  bur  is  next  used  to  smooth  off  the  sharp 
edges  of  the  alveolar  plate  and  to  cut  the  end  of  the  root  and  base  of 
the  crypt  down  to  healthy  tissue.  The  cavity  and  root  end  is  then 
polished  with  a  gold  finishing  bur  or  stone. 

Many  procedures  have  been  resorted  to  in  the  past  to  secure  a 
protection  for  the  exposed  root  end.  Amalgam  has  been  used  with 
more  or  less  success.  Encapsulation  with  gutta  percha  has  been  used. 
Filling  the  apical  end  of  the  canal  with  gold  has  been  tried.  Filling 
the  whole  canal  with  lead  canal  points  and,  after  resecting,  burnishuig 
the  lead  over  the  end  has  been  practiced.  All  of  these  methods  have 
met  with  objections.  None  has  accomplished  the  full  requirement  of 
completely  sealing  over  the  exposed  root  end. 

Silver  reduced  over  the  exposed  ends  of  the  root  seems  to  meet  the 
requirements  of  completely  sealing  the  end  of  the  root  and  does  not 
seem  to  interfere  in  any  way  with  the  process  of  repair. 

The  technic  for  reducing  silver  over  the  resected  end  is  as  follows: 
the  silver  ammonium  oxid  is  applied  by  suitable  pipettes  to  the  dry 
resected  end  of  the  root.  It  is  left  there  for  from  three  to  five  minutes 
after  which  a  small  amount  of  some  reducing  agent  such  as  eugenol  is 


652     EXTRACTION  OF  TEETH  AND  SURGICAL  PROCEDURES 

added  and  left  for  one  minute.  The  excess  is  removed  and^the  resected 
end  burnished  with  a  warm  burnisher.  The  treatment  may  be  repeated 
until  there  is  a  dense  black  layer  of  silver  deposited  over  the  root  end. 

After  the  process  of  reducing  silver  over  the  exposed  end  of  the  root 
is  completed,  the  next  question  to  decide  upon  is  whether  it  is  better 
to  bring  the  edges  of  the  flaps  together  and  suture  or  to  pack  the  wound 
and  let  the  process  of  repair  take  place  by  granulation.  Clinical 
experience  has  shown  that  when  the  crypt  has  not  been  too  extensive, 
repair  will  take  place  more  rapidly  and  with  less  pain  when  the  wound 
has  been  sutured  than  when  left  open,  Horse  hair  or  fine  dermal  suture 
seems  to  be  preferable  to  other  materials  for  this  purpose.  Twenty 
per  cent  solution  argyrol  used  as  a  spray  over  the  wound  immediately 
afterward  and  every  twenty-four  hours  is  indicated  for  postoperative 
treatment. 

In  extensive  cases  when  it  is  deemed  best  not  to  close  the  wound, 
but  to  depend  upon  granulation  for  repair,  iodoform  gauze  packed 
lightly  into  the  crypt  for  twenty-four  to  forty-eight  hours  and  then 
removed  and  the  wound  irrigated  every  twenty-four  hours  thereafter 
with  5  per  cent,  salt  solution  until  repair  is  complete  has  been  the 
treatment  that  has  been  followed  in  the  author's  clinics. 

In  checking  up  with  the  roentgenogram  following  the  operation  of 
apicoectomy,  the  fact  must  not  be  overlooked  that  the  roentgenogram 
is  merely  the  shadow  of  conditions  present.  In  some  cases  it  is  not  at 
all  probable  that  the  regeneration  of  the  new  tissue  will  have  the  same 
density  as  the  original,  consequently  there  may  be  for  sometime  a 
difference  in  the  density  of  the  shadow  and  to  the  inexperienced  this 
may  be  misleading. 

If  this  operation  is  to  take  its  place  in  conservative  dental  practice, 
the  diagnosis  of  the  case  will  play  a  greater  role  in  the  success  or  failure 
than  will  the  technic  of  the  operation.  In  the  final  analysis,  methods 
of  procedure  in  the  operation  play  only  a  small  part,  and  the  methods 
which  are  successful  in  one  man's  practice  might  be  a  failure  in 
another's. 

After  all,  the  final  results  are  the  determining  factors.  There  are 
four  cardinal  points  to  keep  in  mind:  (1)  a  correct  diagnosis  of  the 
case;  (2)  recognition  and  maintenance  of  surgical  asepsis;  (3)  elimina- 
tion of  the  infection;  (4)  complete  sealing  of  the  end  of  the  exposed  root. 

If  these  principles  are  carried  out  in  every  case,  the  results  will  take 
care  of  themselves. 


CHAPTER   XV. 

PRINCIPLES  OF  ORTHODONTIA  FOR  THE  GENERAL 
PRACTITIONER. 

By  FREDERICK  B.  NOYES,  B.A.,  D.D.S. 

The  author's  purpose  in  the  preparation  of  this  chapter  is  to  make  as 
clear  a  statement  as  possible  of  the  fundamental  principles  upon  which 
the  development  of  modern  orthodontia  has  been  based.  It  is  not 
expected  that  it  will  furnish  a  sufficient  basis  for  the  practice  of  ortho- 
dontia, but  that  it  will  give  the  general  practitioner  a  sufficiently  clear 
grasp  of  the  subject  for  him  to  cooperate  intelligently  with  the  special- 
ist to  the  very  great  atlvantage  of  his  pat'ent.  The  general  practi- 
tioner usually  has  the  opportunity  to  see  cases  in  their  early  stages,  at 
the  time  when  treatment  should  be  begun  and  before  so  marked  a 
deformity  has  developed  as  to  attract  the  attention  of  the  laity.  It 
becomes  a  most  important  duty  of  the  general  practitioner  to  recognize 
deviations  from  the  normal  developmental  mechanism,  so  that  during 
the  period  of  dentition  normal  occlusion  may  construct  a  normal 
denture  and  a  balanced  face.  It  is  also  hoped  that  it  may  give  a 
sufficient  statement  of  principles  for  the  beginning  of  his  study  if  he  is 
attracted  to  this  field  of  dental  science. 

The  development  of  modern  orthodontia  from  the  chaotic  condition 
of  fifty  years  ago  may  fairly  be  said  to  have  begun  with  the  recognition 
of  normal  occlusion  as  the  basis  of  the  science.  For  this  the  dental 
profession  is  indebted  to  Dr.  Edward  H.  Angle.  Dr.  Angle  has  defined 
orthodontia  as  "that  science  which  has  for  its  object  the  correction  of 
mal-occlusion  of  the  teeth,"  and  he  follows  the  definition  immediately 
by  the  statement  that  "occlusion  is  the  basis  of  the  science  of  ortho- 
dontia." To  combine  these  statements  in  one  definition,  orthodontia 
might  be  defined  as  the  science  of  occlusion  and  the  art  of  correcting 
mal-occlusion.  One  of  the  most  important  phases  of  the  science  of 
occlusion  is  the  study  of  the  relation  of  the  teeth  to  the  development 
of  the  face. 

Occlusion. — Occlusion  has  been  defined  as  the  relation  of  the  occlusal 
inclined  planes  of  the  teeth  when  the  jaws  are  closed.  Normal  occlu- 
sion is  the  normal  relation  of  these  planes  (Figs.  517,  518  and  519); 
mal-occlusion  is  any  deviation  from  the  normal  relation.     The  study 

(653) 


654     PRINCIPLES  OF  ORTHODONTIA   FOR  THE  PRACTITIONER 

of  normal  occlusion  from  the  orthodontic  standpoint  has  led  to  a  very 
great  development  of  our  understanding  of  the  meaning  and  importance 
of  the  relation  of  the  occlusal  inclined  planes  of  the  teeth.    This  is 


Fia.  517. — Typical  occlusion.     (BroomeU.) 


Fig.  518. — Typicarocclusion;  lingual  view.     (Cryer.) 


OCCLUSION— THE  DEVELOPMENTAL   MECHANISM 


655 


seen  to  be  not  merely  the  relation  of  cusps  for  the  purpose  of  the 
mastication  of  food,  but  a  mechanism  for  the  development  of  the 
denture  as  a  whole  and  the  maintenance  of  it  in  oerfect  function. 
Occlusion  becomes  therefore  not  simply  a  means  of  mastication  but  a 
developmental  mechanism,  through  which  all  of  the  forces  of  function 
are  distributed  in  perfect  balance,  bringing  about  the  normal  develop- 
ment of  the  bones  of  the  face,  the  development  of  the  denture  as  a 
unit  and  the  maintenance  of  each  tooth  in  its  perfect  position. 


Fig.  519. — Typical  occlusion  of  molars;  transverse  view.     (Cryer.) 


OCCLUSION.     THE  DEVELOPMENTAL  MECHANISM. 

In  considering  occlusion  as  a  developmental  mechanism  there  are 
two  phases  to  be  studied:  first,  the  relation  of  the  occlusal  inclined 
planes  of  the  teeth,  which  receive  and  distribute  the  forces  of  function; 
second,  the  forces  of  function,  which  are  distributed  through  the 
occlusal  inclined  planes  of  the  teeth  and  bring  about  the  normal 
development  of  the  supporting  bones.  A  perfect  denture  and  a  normal 
face  therefore  can  only  be  developed  by  a  perfect  mechanism  and 
normal  functional  forces.  If  the  relation  of  the  inclined  planes  is 
abnormal  the  forces  of  function  will  drive  that  tooth  farther  and 
farther  from  its  normal  position  and  unless  the  forces  of  function  are 
normal  in  amount  and  in  proper  balance  the  supporting  bones  will  not 
be  developed  so  as  to  carry  the  teeth  to  their  proper  relation  to  the 
skull  as  a  whole. 

From  the  orthodontic  standpoint  the  unit  of  the  mechanism  is  a 
single  cusp.  Each  cusp  may  be  represented  as  a  four-sided  pjTamid, 
presenting  four  inclined  planes:  (a)  mesio-buccal;  (6)  disto-buccal; 
(c)  mesio-lingual ;  {d)  disto-lingual. 

For  instance,  the  buccal  cusp  of  the  lower  second  bicuspid  occludes 


656     PRINCIPLES  OF  ORTHODONTIA   FOR   THE  PRACTITIONER 

with  the  four  cusps  of  the  upper  bicuspids,  its  mesio-buccal  slope 
antagonizing  the  disto-lingual  slope  of  the  buccal  cusp  of  the  upper 
first;  its  mesio-lingual  slope  antagonizing  the  disto-buccal  slope  of  the 
lingual  cusp  of  the  upper  first;  its  disto-buccal  slope  meeting  the  mesio- 
lingual  slope  of  the  buccal  cusp  of  the  upper  second  bicuspid;  and  its 
disto-lingual  slope,  the  mesio-buccal  slope  of  the  lingual  cusp  of  the 
second  bicuspid.  It  is  therefore  wedged  in  position  both  mesio-distally 
and  bucco-lingually.  The  more  powerful  the  forces  of  function  the  more 
perfectly  the  tooth  is  held  in  position.  In  the  entire  denture,  therefore, 
each  cusp  is  the  unit  upon  the  perfect  relationship  of  which  is  dependent 
the  perfect  development  and  maintenance  of  the  denture.  No  single 
slope  can  be  lacking  without  producing  its  modification  in  the  support 
of  the  entire  machine.  The  problem  of  orthodontia  becomes  that  of 
establishing  and  maintaining  the  normal  relation  of  these  inclined 
planes  and  the  development  of  the  normal  forces  which,  distributed 
in  perfect  balance,  bring  about  the  normal  development  of  the  features, 
the  perfect  development  of  the  masticating  apparatus,  the  health  of  the 
supporting  tissues  and  constitute  the  most  important  factor  in  nature's" 
method  of  cleansing  the  surfaces  of  the  teeth  by  the  mastication  of 
food,  and  consequently  the  prevention  of  caries.  The  beginning  of  the 
study  of  orthodontia,  therefore,  must  be  the  thorough  and  detailed 
study  of  the  relation  of  the  inclined  planes  of  the  cusps  of  the  teeth  in 
the  fully  developed  and  ideal  denture.  This  is  just  as  important  for 
the  general  practitioner  as  for  the  orthodontist,  for  the  preservation 
of  the  denture,  the  health  of  the  supporting  tissues  and  the  prevention 
of  caries  depend  upon  the  preservation  or  restoration  of  the  cusps  of  the 
teeth  and  all  their  inclined  planes.  In  the  past  the  dental  profession 
has  been  too  prone  to  be  satisfied  with  "having  teeth  meet"  without 
regard  to  their  cusp  relationship. 

The  Development  of  the  Denture. — ^Every  practitioner  of  dentistry 
should  have  as  clear  an  idea  as  possible  of  the  development  of  the 
normal  denture  and  a  grasp  of  the  complicated  and  interrelated  forces 
which  are  at  work  throughout  this  whole  period  of  growth.  The  most 
important  factors  in  this  process  car  best  be  studied  from  a  series  of 
skulls  from  infancy  to  adult  life.  At  birth  the  maxillary  bones  contain 
the  germs  for  all  of  the  temporary  teeth  and  all  the  permanent  ones 
except  the  second  and  third  molars.  The  growth  of  these  teeth  in  their 
crypts  exerts  forces  which  are  most  important  factors  in  the  develop- 
ment of  the  bones.  Fig.  520  shows  the  maxillary  bone  of  a  child  of 
about  one  year,  with  the  outer  plate  removed  so  as  to  expose  the  devel- 
oping teeth.  Fig.  521  shows  one  at  about  one  and  a  half  years.  The 
incisors  have  erupted  and  the  growth  of  the  unerupted  cuspid  and  molars 
exerts  forces  which  tend  to  carry  them  in  an  occlusal  and  outward 


OCCLUSION— THE  DEVELOPMENTAL  MECHANISM         G57 

direction.     The  multiplication  of  cells  in  the  formation  of  the  roots 
is  a  very  important  source  of  force  which  is  transmitted  from  the 


Fig.  520. — -Maxillae  at  about  one  year. 


^^^r             ^^^ft  '*  "*'*>'  ^^^^1 

^^^^^^^k^ 

Fig.  521. — Maxillae  at  one  and  one-half  years. 

erupting  teeth  to  the  teeth  already  in  position.     In  Fig.  522  from  the 
skull  of  a  child  in  the  second  year  the  second  temporary  molars  are  seen 

42 


658     PRINCIPLES  OF  ORTHODONTIA  FOR  THE  PRACTITIONER 

to  be  exerting  forces  which  carry  the  incisors  and  cuspids  occlusally 
and  outwardly.  In  this  process  the  entire  bone  is  undergoing  rapid 
transformations,  increasing  the  distance  from  the  floor  of  the  nose  to 
the  incisal  edges  of  the  teeth  and  the  thickness  of  the  mandible  from  the 
lower  border  upward.  In  all  of  this  period  the  action  of  all  of  the 
muscles  attached  to  and  surrounding  the  bones  exerts  pressures  which 
help  to  mold  this  growth.  At  about  three  years  the  temporary  denture 
is  complete.  A  comparison  of  Fig.  523  with  the  previous  figures  shows 
the  changes  in  the  bone.     During  the  period  of  the  function  of  the 


Fig.  522. — Maxillae  in  the  second  year,  showing  the  relation  of  the  erupting  teeth. 
Note  the  relation  offjthe  crypt  of  the  second  molar  to  the  inferior  dental  canal. 

temporary  denture,  from  three  to  six  years  of  age,  while  the  teeth  retain 
their  same  relation  to  each  other,  they  do  not  retain  the  same  relation 
to  the  skull.  During  this  entire  period  they  are  constantly  moving  in 
three  dimensions  of  space,  under  the  influence  of  muscular  pressures 
and  forces  exerted  by  the  development  of  the  permanent  teeth.  For 
the  present  we  shall  consider  only  the  forces  exerted  by  the  developing 
teeth.  Each  permanent  tooth  is  enclosed  in  a  bony  wall  or  crypt. 
The  multiplication  of  cells  within  this  crypt  pushes  the  wall  back  until 
the  resistance  below  is  greater  than  the  resistance  above.     Between 


OCCLUSION— THE  DEVELOPMENTAL  MECHANISM         659 

five  and  six  years  of  age  the  first  permanent  molars  in  their  crypts  exert 
forces  at  the  distal  of  the  temporary  denture,  carrying  all  of  the  tem- 
porary teeth  forward  and  occlusally  until  room  has  been  made  for  their 
eruption.  The  second  temporary  molars  guide  them  into  relation 
with  their  antagonists,  but  there  is  a  period  when  they  are  coming  into 
occlusal  relation,  during  which  comparatively  slight  variations  from 
normal  muscular  pressures  and  action  may  cause  their  cusps  to  lock 
abnormally  and  pervert  the  whole  future  development.  The  first 
permanent  molars  should  erupt  and  lock  their  cusps  in  normal  relation 
before  the  first  temporary  tooth  is  shed,  and  during  the  whole  period  in 


Fig.  523. — The  complete  temporary  dentition  (about  three  years),  showing  the 
relation  of  the  developing  permanent  teeth. 

which  the  permanent  teeth  are  being  substituted  for  the  temporary 
ones  the  first  molars  maintain  the  relation  of  the  maxilla  and  mandible. 
The  importance  of  the  normal  locking  of  these  teeth  will  therefore  be 
recognized  at  once.  The  abnormal  relation  not  only  shifts  the  position 
of  the  mandible  with  reference  to  the  maxilla  but  changes  the  balance 
of  muscular  forces,  which  modify  the  development  of  the  entire  man- 
dible. Every  child  should  be  examined  when  the  first  molars  are 
erupted  to  see  that  they  lock  their  cusps  in  normal  relation. 

Between  the  ages  of  five  and  seven  the  most  active  growth  is  in  the 
region  of  the  incisors,  increasing  the  arc  from  cuspid  to  cuspid  and 


660     PRINCIPLES  OF  ORTHODONTIA   FOR   THE  PRACTITIONER 

making  the  room  required  for  the  increased  size  of  the  permanent 
incisors.  While  at  four  years  the  temporary  incisors  should  be  in 
contact  with  each  other  on  their  mesial  and  distal  surfaces,  before 
they  are  shed  they  should  be  standing  wide  apart  with  large  spaces 
between  them.  This  is  brought  about  by  the  development  of  the 
permanent  incisors  and  cuspids,  and  the  relationship  of  the  root  of 


Fig.  524. — Front  view  of  the  skull.     Note  the  relation  of  the  permanent  incisors  and 
cuspids  to  each  other  and  the  roots  of  the  temporary  teeth. 

the  temporary  cuspid  to  the  tip  of  the  developing  permanent  cuspid 
is  a  most  important  factor.  The  normal  relationship  is  shown  in  Fig. 
524.  As  the  permanent  teeth  develop  they  carry  the  temporary  teeth, 
alveolar  process  and  all,  in  an  occlusal  and  outward  direction.  The 
loss  of  any  factor  in  the  relationship  will  result  in  the  failure  of  the 
proper  distribution  of  forces.     For  instance  a  slight  shifting  of  the 


OCCLUSION— THE  DEVELOrMENTAL   MECHANISM         001 

temporary  cuspid  distally  because  of  the  loss  of  teuiporary  molars, 
ill  whole  or  in  part,  will  cause  its  root  to  lose  the  normal  relation  to  the 
permanent  cuspid  and  the  growth  of  the  long  cuspid  root  will  not  bring 
about  the  normal  development  of  bone  in  this  region  (Fig.  525). 


Fig.  525. — Dentition  in  the  eighth  year.     Note  the  position  of  the  cuspids  and 
compare  with  Fig.  526. 


Between  the  ages  of  six  and  eight  the  permanent  incisors  come  into 
place  and  take  their  normal  relationship.  Between  the  ages  of  eight 
and  eleven  growth  is  most  active  in  the  region  from  the  cuspid  to  the 
second  molar  and  is  largely  dependent  on  the  development  of  the 
bicuspids,  which  force  the  temporary  molars  occlusally,  and  on  the 
development  of  the  second  molars,  pushing  at  the  distal  of  the  first 
(Figs.  526,  527,  528  and  529).    It  is  important  to  emphasize  that  dur- 


662    PRINCIPLES  OF  ORTHODONTIA  FOR   THE   PRACTITIONER 

ing  the  entire  period  of  development  the  teeth  are  moving  under  the 
influence  of  developmental  forces  and  are  being  carried  into  new  posi- 
tions with  relation  to  the  skull  by  the  growth  of  bone.  The  process  is 
dependent  upon  the  maintenance  of  each  tooth  until  the  normal  time 
for  its  loss,  and  the  extraction  of  a  tooth  does  not  make  more  space  but 


Fig.  526. — Dentition  in  the  eleventh  year.     Note  the  growth  of  the  cuspids  and 
bicuspids.     The  second  molar  is  about  to  erupt. 

less.  It  would  seem  unnecessary  to  emphasize  the  importance  of  the 
temporary  molars.  Nature  provides  a  slightly  greater  mesio-distal 
diameter  of  the  temporary  molars  as  compared  with  the  bicuspids  so 
as  to  allow  space  for  their  eruption.  If  the  temporary  molar  is  pre- 
maturely lost  the  second  permanent  molar  will  crowd  the  first  molar 
mesially  before  the  bicuspid  can  take  its  place. 


OCCLVmOM—TlIl^  DEVELOPMENTAL  MECHAnISM         663 

After  the  eruption  of  the  second  molars  and  bicuspids  the  movement 
of  all  of  the  teeth  in  the  denture  should  continue  under  the  influence 
of  muscular  pressure  and  the  growth  of  the  third  molars.  Compare 
in  Figs.  527  and  529  the  distance  from  the  tip  of  the  upper  incisor  root 
to  the  floor  of  the  nose  and  of  the  lower  incisors  and  cuspids  to  the 
lower  border  of  the  mandible,  between  the  ages  of  thirteen  and  a  fully 
developed  adult.  This  growth  seems  to  be  dependent  upon  the  vigor 
of  muscular  action  which  stimulates  cell  activity  in  the  bone  not  only 
by  mechanical  influence  but  by  the  increase  of  blood  circulation. 


^^^^^^^H 

w                     ^      ^^^^1 

w  -"^                              ^^  ^^^1 

l[»-'^^f|^'  .-              -*^'  ;  ^H 

^      y   J   \     ^^     -  ^l^ 

^■^'^"'^^^^ 

^'"^         ■*-     jJ|      f      i  ^^^^1 

^       ''^A'  f-S  i^  .^H 

B^^^^jH 

Fig.  527. — Dentition  in  the  thirteenth  year.     Note  the  relation  of  the  bicuspid 
crown  to  the  roots  of  the  lower  temporary  molar. 

The  Forces  Governing  Occlusion. — The  forces  governing  occlusion 
are  defined  as  those  forces  which  tend  to  guide  the  teeth  into  their 
normal  relation  to  each  other  and  their  normal  position  with  refer- 
ence to  the  skull.  They  may  be  divided  into  two  classes — potential 
forces  and  dynamic  forces.  The  potential  forces  are:  (1)  the  occlusal 
inclined  planes  of  the  teeth,  which  distribute  through  the  opposing 
planes  the  forces  of  function  and  growth;  (2)  the  contact  of  approxi- 
mating surfaces  of  the  teeth,  which  distribute  through  the  entire  den- 
ture the  forces  of  developing  and  unerupted  teeth;    (3)  the  resultant 


664     PRINCIPLES  OF  ORTHODONTIA   FOR  THE  PRACTITIONER 

harmony  in  the  size  and  relation  of  the  arches.     Through  these  poten- 
tial agencies  the  dynamic  forces  are  distributed. 

The  dynamic  forces  are:  (a)  cell  activity;  (6)  muscular  action  and 
pressure:  (1)  respiration;  (2)  deglutition;  (3)  mastication;  (4)  speech; 
(5)  expression;  (6)  atmospheric  pressure;  (7)  attention  and  muscular 
tone. 


Fig.  528. — The  dentition  of  a  young  adult.     The  third  molars  have  not  erupted. 
(About  fifteen  years.) 

(a)  Cell  Activity. — It  has  long  been  known  that  in  the  multiplication 
of  cells  very  considerable  forces  are  generated.  The  sprouting  seed 
forces  its  way  through  the  earth;  growing  rootlets,  entering  between 
stones,  force  them  apart.  The  forces  generated  by  the  multiplication 
of  plant  cells  have  been  studied  and  more  or  less  accurately  measured 


OCCLUSION— THE  DEVELOPMENTAL  MECHANISM         005 

by  botanists.  The  same  forces  in  the  niukiphcation  of  c-ells  in  the 
growth  of  the  tooth  germ  and  in  the  development  of  the  tooth  roots 
are  important  sources  of  dynamic  energy  in  the  development  of  the 
denture.  Not  much  is  known  of  their  nature,  but  they  are  evidently 
dependent  upon  general  nutrition  and  vital  energy.  We  see  many 
instances,  especially  in  frail  individuals,  in  which  the  cellular  activities 
do  not  manifest  sufficient  energy  to  exert  their  normal  forces. 


Fig.  529. — Adult  dentition.     Note  the  distance  from  the  apices  of  the  incisors  to 
the  lowest  border  of  the  mandible  and  the  floor  of  the  nose. 

(6)  Muscular  Action  and  Pressure. — All  of  the  forces  generated  by 
muscular  action  in  the  performance  of  function  are  distributed  through 
the  potential  forces  and  the  growth  of  the  supporting  bones  is  a  response 
to  these  mechanical  stimuli.  The  positions  which  the  teeth  come  to 
occupy  are  dependent  upon  the  vigor  and  balance  of  these  functions. 
Failure  of  normal  action  or  abnormal  balance  of  action  results  in  pro- 
portional underdevelopment  of  bone  and  modification  of  the  dentm-e, 
and  may  lead  to  the  perversion  of  the  potential  forces.  It  may  be 
worth  while  to  examine  somewhat  in  detail  the  action  of  the  individual 
functions. 


666     PRINCIPLES  OF  ORTHODONTIA  FOR  fHE  PRACflTlONm 

1.  Bespiration. — Respiration  is  probably  the  most  important  func- 
tion with  reference  to  the  development  of  the  denture,  for  it  is  in  con- 
stant action.  Nature  intended  man  to  breathe  through  the  nose.  In 
order  to  exert  its  normal  influence  respiration  must  be  not  only  normal 
in  performance  but  sufficiently  vigorous  in  action.  In  forced  respira- 
tion the  muscles  attached  to  the  hyoid  bone  are  vigorously  contracted, 
drawing  the  tongue  upward  and  forward,  forcing  it  against  the  lingual 
surfaces  of  the  teeth  and  the  supporting  bones.  This  is  one  of  the 
most  important  factors  in  the  development  of  the  dental  arches.  The 
author  has  been  amazed  at  the  instruction  given  by  physical  directors 
in  high  schools  in  training  boys  for  track  teams  to  have  them  breathe 
through  the  mouth. 

2.  Deglutition. — The  normal  individual  who  breathes  through  the 
nose  swallows  about  once  in  two  minutes,  night  and  day.  In  this  act 
the  muscles  attached  to  the  hyoid  bone  are  also  contracted,  and  pres- 
sures are  exerted  as  in  forced  respiration.  One  need  only  to  close  the 
lips  and  swallow  voluntarily  to  be  conscious  of  the  pressures  exerted. 
When  breathing  is  carried  on  normally  the  secretions  collect  in  the 
mouth  and  are  expelled  by  swallowing,  so  that  this  impulse  to  growth  is 
repeated  at  frequent  intervals,  night  and  day,  and  becomes  an  impor- 
tant factor  in  development.  If  respiration  is  carried  on  through  the 
mouth  the  secretions  are  evaporated  by  the  air,  swallowing  is  omitted 
and  this  impulse  to  growth  is  lost,  with  consequent  lack  of  development 
in  the  dental  arches. 

3.  Mastication. — ^While  mastication  is  the  first  functional  force  to  be 
thought  of  in  connection  with  the  development  of  the  dental  arches  it  is 
undoubtedly  not  the  most  important,  for  it  is  most  intermittent  in 
action.  On  the  other  hand  its  action  has  the  most  direct  influence 
upon  the  bone  of  the  alveolar  process,  stimulating  both  its  blood  supply 
and  its  cell  activity.  It  is  the  grinding  motions  of  the  teeth  which 
exert  the  most  influence  in  modifying  the  form  of  the  dental  arches. 
In  this  action  the  lower  teeth  are  forced  against  the  lingual  slopes  of  the 
buccal  cusps  of  the  upper  teeth  in  such  a  way  as  to  tend  to  widen  and 
round  the  dental  arches.  This  is  markedly  seen  in  the  study  of  the 
relation  of  the  diet  to  the  form  of  the  denture  in  different  races.  The 
meat-eater  tends  to  have  a  long  narrow  arch;  the  vegetable-eater,  a 
broad,  round  arch.  Many  cases  of  mal-occlusion  would  never  develop 
if  the  child  ate  the  shredded  wheat  biscuit  and  drank  the  cream  instead 
of  soaking  the  cereal  and  swallowing  it  without  mastication. 

4.  Speech. — Space  will  not  permit  the  detailed  examination  of  the 
influence  of  speech  on  the  development  of  the  denture  and  the  bones  of 
the  face,  but  it  exerts  an  important  influence,  especially  in  the  forces 


OCCLUSION— THE  DEVELOPMENTAL  MECHANISM         667 

acting  upon  the  labial  and  buccal  surfaces  of  the  teeth  and  bones. 
It  is  interesting  to  note  that  anthropologists  have  long  since  pointed 
out  that  the  development  of  the  chin  begins  with  the  power  of  speech, 
and  all  forceful  speakers  have  a  well-developed  chin.  Training  in 
elocution  sometimes  becomes  a  help  in  the  correction  of  mal-occlusion. 

5.  Expression. — Most  mental  states  are  accompanied  by  action  of 
the  facial  muscles,  which  react  through  the  potential  forces  in  the 
molding  of  the  bones.  Certain  mal-occlusions  are  undoubtedly  related 
to  habitual  mental  states,  and  in  a  very  literal  way  every  thought  molds 
not  only  the  expression  but  the  framework  of  the  face. 

6.  Atmospheric  Pressure. — Atmospheric  pressure  is  closely  related 
to  the  function  of  deglutition  and  nasal  breathing.  In  swallowing  with 
the  lips  closed  the  air  and  liquid  contents  of  the  mouth  cavity  are 
expelled,  the  soft  palate  is  brought  into  contact  with  the  posterior 
portion  of  the  tongue,  and,  as  the  muscular  action  relaxes,  a  partial 
vacuum  is  produced,  which  exerts  a  downward  pressure  upon  the  roof 
of  the  mouth,  a  pressure  of  the  lips  against  the  labial  surfaces  of  the 
incisors,  and  pressure  against  the  lingual  surfaces  of  the  buccal  teeth. 
In  nasal  respiration,  inhalation  and  exhalation,  in  proportion  to  their 
vigor,  produce  alterations  of  atmospheric  pressure  in  the  nasal  spaces 
and  their  accessory  sinuses,  which,  exerted  against  the  walls  of  these 
cavities,  bring  about  their  normal  development. 

7.  Attention  and  Muscular  Tone. — In  recent  literature  we  have  often 
seen  the  statement  that  the  occlusal  surfaces  of  the  teeth  are  not  held 
in  contact.  This  statement  is  literally  true  of  the  idiot  but  not  of  the 
normal  individual.  In  proportion  as  the  attention  is  dhected  and 
concentrated  the  teeth  are  brought  firmly  in  contact.  To  demon- 
strate this,  one  need  only  see  a  child  sitting  in  a  dreamy  state  with  the 
lips  parted  and  jaw  dropped,  and  speak  to  him  quickly  or  sharply  and 
see  the  lips  tighten  and  the  teeth  come  together  with  a  click.  The  lack 
of  concentration  arid  attention  as  a  general  state  is  responsible  for  a 
lowering  of  muscular  tone,  not  only  in  the  muscles  of  the  face,  but  of 
the  entire  body.  It  is  important  to  remember  that  we  cannot  expect 
to  have  the  normal  muscular  tone  in  the  muscles  which  mold  the 
denture  if  it  is  absent  in  the  general  muscular  system. 

In  the  consideration  of  the  forces  governing  occlusion,  therefore,  we 
see  in  the  potential  forces  a  machine  which,  actuated  by  the  power 
generated  by  the  dynamic  forces,  molds  the  entire  development  of  the 
features.  In  order  that  the  face  may  become  the  expression  of  the 
individual  and  an  index  of  his  personality,  we  must  maintain  through 
the  developmental  period  the  perfect  action  of  the  machine  and  the 
normal  balance  of  the  forces. 


668     PRINCIPLES  OF  ORTHODONTIA   FOR   THE  PRACTITIONER 

ETIOLOGY  OF  MAL-OCCLUSION. 

1.  Mechanical. 

(a)  Loss  or  perversion  of  the  potential  forces  governing  occlusion. 

(b)  Premature  loss  of  temporary  teeth  in  whole  or  in  part. 

(c)  Prolonged  retention  of  temporary  teeth. 

(d)  Loss  or  absence  of  permanent  teeth. 

(e)  Improper  or  imperfect  restorations. 

2.  Abnormal  functional  habits. 

(a)  Abnormal  breathing  and  lack  of  sufficient  vigor  of  breathing. 
(6)  Loss  of  normal  swallowing. 
(c)  Snuffles  and  similar  habits. 

3.  Abnormal  nervous  habits. 

(a)  Thumb  sucking. 

(b)  Lip  and  tongue  habits. 

4.  Psychological. 

(a)  Associated  with  mouth-breathing. 

(b)  Mental  states. 

5.  Pathologic  conditions. 

(a)  Destruction  of  supporting  tissues. 
(6)  Pathologic  growths. 

6.  Accidents  and  injuries. 

(a)  Mutilations. 

(b)  Burns. 

7.  Freaks  and  deformities. 

From  the  study  of  the  development  of  the  normal  denture  it  is 
apparent  that  the  causes  of  mal-occlusion  are  but  the  perversion  of 
nature's  plan.  The  purposes  of  this  chapter  do  not  allow  for  the 
elaboration  of  these  in  detail. 

NOMENCLATURE  AND  CLASSIFICATION. 

Seven  words  and  their  combinations  will  describe  accurately  any 
position  that  a  tooth  out  of  harmony  with  the  line  of  occlusion  may 
occupy.  These  terms  are  generally  accepted  and  used  in  the  literature 
of  orthodontia. 

1.  Labial  or  buccal  occlusion. 

2.  Lingual  occlusion. 

3.  Mesial  occlusion, 

4.  Distal  occlusion. 

5.  Infra  occlusion. 

6.  Supra  occlusion. 

7.  Torso  occlusion. 


NOMENCLATURE  AND  CLASSIFICATION  669 

Two  or  even  three  of  them  may  be  combhied  in  the  description  of  the 
position  of  a  single  tooth.  For  instance,  a  canine  nearer  the  median 
line  and  farther  to  the  labial  than  normal,  and  at  the  same  time  turned 
on  its  axis,  would  be  said  to  be  in  mesio-labio-torso  occlusion. 

Classification. — The  Angle  classification  has  undoubtedly  been  one  of 
the  very  important  factors  in  the  development  of  orthodontia,  since  for 
the  first  time  in  the  history  of  the  subject  it  gave  a  scientific  grouping 
of  cases  upon  which  the  procedures  in  treatment  could  be  based.  The 
Angle  classification  is  great  because  it  is  not  an  arbitrary  grouping  of 
cases  by  the  mesio-distal  relation  of  two  teeth,  but  the  mesio-distal 
relation  of  the  first  permanent  molars  is  recognized  as  the  most  impor- 
tant single  factor  in  the  development  of  the  denture,  and  therefore  it  is 
made  the  basis  of  the  grouping.  Whatever  modification  there  may  be 
in  it  in  the  future  it  will  undoubtedly  remain  fundamentally  unchanged. 

Before  giving  the  classification  of  mal-occlusion  I  want  to  quote  this 
paragraph  from  Dr.  Angle's  book,  stating  the  basis  of  classification. 
He  says: 

"These  classes  are  based  on  the  mesio-distal  relations  of  the  teeth, 
dental  arches  and  jaws,  which  depend  primarily  upon  the  positions 
mesio-distally  assumed  by  the  first  permanent  molars  on  their  erupt- 
ing and  locking.  Hence,  in  diagnosing  cases  of  mal-occlusion  we  must 
consider,  first,  the  mesio-distal  relations  of  the  jaws  and  dental  arches 
as  indicated  by  the  relation  of  the  lower  first  molars  with  the  upper 
first  molars — the  keys  to  occlusion;  and  second,  the  positions  of  the 
individual  teeth,  carefully  noting  their  relations  to  the  line  of  occlusion. 

Class  I. — Arches  in  normal  mesio-distal  relations,  as  indicated  by 
the  first  molars. 

Class  H. — Lower  arch  distal  to  normal  in  its  relation  to  the  upper 
arch,  as  indicated  by  the  first  molars. 

Division  H. — Bilaterally  distal,  protruding  upper  incisors.  Pri- 
marily, at  least,  associated  with  mouth-breathing. 

Subdivision. — Unilaterally  distal,  protrudmg  upper  incisors.  Pri- 
marily, at  least,  associated  with  mouth-breathing. 

Division. — Bilaterally  distal,  retruding  upper  incisors.  Normal 
breathers. 

Subdivision. — Unilaterally  distal,  retruding  upper  incisors.  Normal 
breathers. 

Class  HI. — Lower  arch  mesial  to  normal  in  its  relation  to  upper 
arch,  as  indicated  by  the  first  molars. 

Division . — Bilaterally  mesial. 

Subdivision. — Unilaterally  mesial. 

Every  practitioner  of  dentistry  should  be  thoroughly  familiar  with 
this  classification  and  able  to  recognize  any  mal-occlusion  at  once,  and 


670     PRINCIPLES  OF  ORTHODONTIA   FOR  THE  PRACTITIONER 

name  the  divisions  or  subdivisions  to  which  it  belongs.  It  is  so 
simple  and  so  easily  grasped  that  a  very  little  consideration  will  enable 
anyone  to  do  this. 

FUNDAMENTAL  PRINCIPLES  OF  TREATMENT. 

Growth  Not  Tooth  Movement. — The  first  great  fundamental  principle 
that  must  be  clearly  grasped  in  considering  treatment  is  that  during 
the  entire  period  of  growth  the  teeth  are  moving  in  three  dimensions 
of  space  by  the  development  of  bone  under  the  influence  of  natural 
forces.  This  movement  in  no  way  differs  from  ideal  movement  by 
artificial  force,  and  the  tissue  changes  in  the  two  are  identical.  The 
author  could  show  in  sections  identical  reactions  of  bone  to  natural 
forces  and  to  properly  controlled  and  directed  artificial  forces  exerted 
upon  the  teeth  by  mechanical  appliances.  The  teeth  are  not,  or  should 
not  be,  pushed  through  the  tissues,  but  are  carried  by  tissue  activity  into 
their  normal  positions  and  relations. 

Treatment  must  force,  or,  better,  enable  nature  to  carry  out  her  ideal 
or  intention,  and  so  teeth  should  move  in  the  direction  and  the  manner 
of  the  normal  process.  To  illustrate,  a  dental  arch  is  to  be  widened  at 
the  first  bicuspids.  While  the  teeth  are  moving  buccally  they  are  also 
moving  occlusally.  Incisors  are  to  be  moved  labially,  but  while  they 
are  moving  in  that  direction  they  are  also  moving  incisally,  increasing 
the  distance  from  the  floor  of  the  nose.  It  has  been  the  tendency  to 
think  of  tooth  movement  in  terms  of  two  dimensions.  It  should  be 
thought  of  in  three  dimensions.  The  tissues  respond  better  and  more 
easily  to  stimulation  to  growth  in  their  normal  directions  than  to 
forces  opposed  to  them. 

In  natural  processes  growth  is  intermittent.  A  period  of  rapid 
advance  is  followed  by  one  of  organization  and  the  gathering  of  forces 
for  a  new  advance.  In  the  stimulation  of  growth  by  artificial  forces 
the  stimulus  should  not  be  repeated  more  rapidly  than  the  tissue  can 
organize  and  prepare  for  a  new  growth.  Time  was  when  orthodontic 
appliances  were  tightened  every  day  or  two.  No  tissue  could  maintain 
such  a  pace. 

Whatever  the  form  of  appliance  used  to  generate  the  force  the  force 
must  be  positive  in  character,  constant  in  direction,  moderate  in  amount 
and  limited  in  range  of  action.  Inflammation  is  at  once  set  up  in  the 
tissue  if  the  tooth  is  allowed  to  move  back  and  forth  or  if  the  force 
is  constantly  changing  direction.  It  is  surprising  how  quickly  soreness 
can  be  set  up  when  these  conditions  occur. 

Time  of  Treatment. — As  soon  as  a  definite  fault  in  the  mechanism 
of  development  which  makes  its  further  normal  action  impossible  is 


FUNDAMENTAL  PRINCIPLES  OF  TREATMENT  G71 

discovered  it  should  be  corrected,  so  that  the  natural  forces  may  con- 
tinue normal  development.  Mal-occlusion  in  the  temporary  denture  is 
comparatively  rare,  but  if  it  occurs  it  should  be  corrected  at  once  and 
every  effort  made  to  establish  and  maintain  the  normal  developmental 
mechanism.  ^Yhile  the  author  is  heartily  in  favor  of  early  treatment 
the  most  common  mistake  that  is  being  made  at  present  is  the  wearing 
of  inefficient  appliances  continuously  for  long  periods.  There  are 
definite  periods  in  which  certain  things  should  be  done.  The  work 
should  be  accomplished  rapidly  with  a  positive  and  efficient  appliance, 
the  results  maintained,  and  then  nature  given  a  chance  to  carry  on  her 
work  under  the  normal  influences  of  growth. 

Periods  of  Active  Treatment. — In  the  development  of  the  denture  there 
are  certain  periods  of  danger,  and  especially  active  gro-^-th.  These 
should  be  the  periods  of  active  treatment. 

1.  The  Eruption  of  the  First  Permanent  Molars. — If  when  these 
teeth  erupt  they  do  not  lock  normally,  appliances  should  be  placed 
on  the  teeth  and  the  necessary  movements  accomplished  to  lock  them 
normally.  They  should  then  be  retained  in  their  normal  relation  until 
their  cusps  have  been  firmly  locked,  when  all  appliances  should  be 
removed  and  nature  allowed  to  proceed. 

2.  When  the  Permanent  Incisors  Erupt. — If  the  development  in  this 
region  is  deficient  appliances  should  be  placed,  the  necessary  develop- 
ment accomplished  and  retained  for  a  comparatively  short  time  and 
nature  allowed  to  proceed  again. 

3.  While  the  Bicuspich  and  Second  Molars  are  Erupting. — ^This 
should  be  the  final  period  of  treatment.  Very  often  work  during  this 
period  is  commenced  too  soon  and  as  a  result  it  is  necessary  to  wear 
appliances  for  a  long  time,  waiting  for  the  eruption  of  some  tooth. 

Time  of  Completion  of  Treatment. — All  orthodontic  treatment  should 
be  completed  by  the  time  the  second  molars  are  in  full  occlusion,  but 
because  of  the  deficiency  of  the  forces  which  should  cause  the  develop- 
ment in  the  width  of  the  arches  it  is  often  necessary  to  use  some  simple 
method  of  maintaining  the  width  for  a  long  time. 

Means  of  Treatment. — ^There  are  tw^o  means  of  treatment  at  the 
command  of  the  orthodontist: 

1.  The  use  of  artificial  forces  derived  from  mechanical  appliances. 

2.  The  development  and  stimulation  of  natural  forces  of  function. 
In  the  past  it  is  certainly  true  that  too  much  attention  and  reliance 

have  been  placed  on  the  first  and  too  little  on  the  latter.  It  is  much 
easier  to  make  an  appliance  to  replace  or  supplement  a  deficient  natural 
function  than  to  develop  it  to  normal  power.  During  active  treatment 
positive  and  efiicient  appliances  should  accomplish  definite  results  as 
rapidly  as  possible.     During  retention  and  between  periods  of  active 


672     PRINCIPLES  OF  ORTHODONTIA  FOR   THE  PRACTITIONER 

treatment  attention  should  be  given  to  the  development  of  the  natura. 
forces,  for  it  must  be  remembered  that  throughout  life  the  teeth  remain 
only  in  the  position  in  which  all  of  the  forces  to  which  they  are  sub- 
jected are  balanced. 

Complications  of  Treatment. — Caries. — Caries  during  orthodontic 
treatment  is  a  serious  matter  and  requires  the  cooperation  of  the 
orthodontist,  the  dentist,  the  parents  and  the  patient.  With  reason- 
able cooperation  of  all  there  is  no  reason  for  damage  to  the  teeth. 
With  the  modern  appliance  the  teeth  can  be  kept  clean  with  reasonable 
effort.     Three  things  are  most  important: 

1.  The  care  of  the  teeth  by  the  dentist  before  treatment  and  in 
intervals  between  active  treatments. 

2.  The  systematic  instruction  and  training  of  the  patient  in  cleansing 
the  mouth. 

3.  The  insistence  upon  carrying  out  of  the  instruction. 

Loss  of  Dental  Pulys. — Pulps  may  be  destroyed  by  unreasonable  and 
improper  application  of  force  through  orthodontic  appliances,  but  it 
seems  equally  certain  that  reasonable  use  of  appliances  will  not  endanger' 
the  life  and  activity  of  the  pulp.  Many  cases  of  pulp  destruction  during 
treatment  are  in  no  way  related  to  the  treatment.  In  the  last  few 
years  the  author  has  seen  several  instances  in  which  pulp  destruction 
occurred  during  treatment  in  teeth  that  had  never  had  any  artificial 
force  applied  to  them  and  the  occurrence  could  not  possibly  be  referred 
to  the  treatment. 

Inflammation  of  the  Gums. — Hypertrophic  inflammation  of  the  gum 
margins  caused  by  filth  is  not  uncommon  in  children  from  eight  to 
twelve  years  of  age.  The  same  condition  sometimes  occurs  during 
orthodontic  treatment.  It  is  caused  by  lack  of  proper  mouth  hygiene, 
but  may  be  augmented  by  sloven  technic  in  the  application  of  bands. 
When  it  occurs  the  bands  must  be  removed  and  the  conditions  reduced. 
If  it  cannot  be  prevented  when  the  appliances  are  replaced  the  treat- 
ment should  be  abandoned  until  the  patient  can  be  made  to  keep  the 
mouth  clean. 

Absorption  of  Permanent  Tooth  R,oots. — ^This  is  probably  due  to 
improper  application  of  force,  the  attempt  to  move  teeth  in  an  impos- 
sible direction  or  improper  control  of  force.  Such  absorptions  occur, 
however,  in  rare  instances  when  there  has  been  no  orthodontic  treat- 
ment, and  caution  should  be  used  in  blaming  the  treatment  for  it 
without  good  evidence.  When  it  is  caused  by  the  orthodontic  appliance 
the  author  believes  that  it  is  usually  the  result  of  lack  of  constancy  in 
the  direction  of  the  force,  or  by  forcing  the  root  against  some  such 
impossible  resistance  as  the  root  of  another  tooth. 


PRINCIPLES  OF  ORTHODONTIC  TECHNIC  673 

PRINCIPLES  OF  ORTHODONTIC  TECHNIC. 

The  first  requirements  in  orthodontic  procedure  or  examination  are : 

1 .  Perfect  models  from  accurate  plaster  impressions  which  show  not 
only  the  teeth  and  their  occlusal  relations  but  the  details  of  bone  struc- 
ture as  far  as  the  attachments  of  the  soft  tissues  will  permit. 

2.  Photographs  of  the  face  showing  correctly  the  features  in  repose, 
both  front  view  and  profile,  and 

3.  Roentgenograms  showing  the  roots  of  the  teeth  and  unerupted 
teeth.  Instruction  in  technical  methods  is  beyond  the  scope  of  this 
chapter.  For  such  instruction  those  interested  are  referred  to  the 
standard  text-books. 

The  record  of  the  original  conditions  is  the  foundation  of  all  treat- 
ment, and  no  adjustment  should  ever  be  made  without  first  determining 
the  distance  and  direction  in  which  the  tooth  has  been  moved  and 
exactly  what  is  to  be  accomplished  by  the  adjustment  contemplated. 
If  fewer  adjustments  were  made  and  each  were  studied  more  carefully 
orthodontic  treatment  would  be  accomplished  faster  and  better. 

Soldering. — Orthodontia  has  developed  a  soldering  technic  which  is 
fundamentally  different  from  that  used  generally  in  dentistry.  In 
dentistry  large  masses  of  solder  are  used  to  unite  masses  of  metal  often 
widely  separated.     The  principles  of  orthodontic  soldering  are: 

1.  Perfect  contact  of  the  metal  surfaces  to  be  united. 

2,  Perfect  union  with  the  smallest  amount  of  solder.  Strength 
depends  upon  perfection  of  contact  and  area  of  surface  united. 

Sloppiness  in  soldering  is  a  common  cause  of  inefficiency  in  an 
appliance.  For  instruction  in  soldering  technic  the  student  is  referred 
to  text-books  on  orthodontia,  but  the  beginner  must  realize  that  he  is 
to  master  a  new  set  of  principles  not  generally  used  in  dentistry. 

Appliances. — It  is  not  the  appliance  but  the  intelligence  with  which 
it  is  used  that  accomplishes  results  in  orthodontia.  Undoubtedly 
results  may  be  obtained  with  very  clumsy  and  inefficient  appliances 
used  with  skill  and  knowledge.  The  rational  method  is  to  find  the 
appliance  that  will  furnish  the  most  positive  and  efficient  force  under 
the  most  perfect  control  and  then  learn  to  apply  it  with  knowledge, 
judgment  and  skill.  Satisfactory  results  will  never  be  attained  by  using 
a  different  appliance  in  each  case. 

In  the  author's  opinion  the  ribbon  arch  and  bracket  band  appliance 
possesses  the  above  requirements  to  a  greater  degree  than  any  instru- 
ment yet  devised,  but  it  will  never  be  used  with  success  except  by  those 
who  exercise  the  most  painstaking  accuracy  and  skill  in  its  adjustment 
and  the  highest  degree  of  knowledge  and  judgment  in  its  application. 
An  inefficient  appliance  is  less  dangerous  in  careless  and  inexperienced 
43 


674      PRINCIPLES  OF  ORTHODONTIA  FOR  THE  PRACTITIONER 

hands  than  an  efficient  one,  for  it  will  produce  results  so  slowly  that 
undesirable  results  may  be  noted  before  serious  damage  has  been  done 
while  improper  adjustment  of  an  efficient  instrument  produces  bad 
results  with  the  same  precision  that  proper  adjustment  does  in  bringing 
about  the  desired  end. 
Retention. — ^There  are  three  periods  in  retention: 

1.  Fixation. 

2.  Antagonizing  tendency  to  return  to  old  position. 

3.  Establishment  of  the  normal  balance  of  forces. 

After  teeth  have  been  moved  from  a  position  of  mal-occlusion  into 
harmony  with  the  line  of  occlusion  they  must  be  fixed  in  the  new  posi- 
tion for  a  very  brief  period — just  long  enough  for  the  primary  readjust- 
ment and  reorganization  of  the  supporting  tissues.  This  is  best  accom- 
plished by  allowing  the  working  appliance  to  remain  in  a  state  of  rest 
for  a  short  time. 

If  appliances  are  removed  the  teeth  will  rapidly  return  to  their 
original  positions.  The  retaining  device  should  antagonize  this  tend- 
ency to  return,  but  limit  the  freedom  of  the  teeth  in  no  other  way, 
leaving  them  exposed  to  all  the  action  of  the  normal  forces.  If  in 
the  new  position  the  forces  are  balanced  the  supporting  tissue  will 
rapidly  be  completely  reorganized.  The  obtaining  of  the  normal 
balance  of  force  is  often  the  most  difficult  problem,  especially  when 
it  involves  the  breaking  up  of  old  and  long-established  abnormal 
functional  habits  and  the  establishment  of  new  and  normal  ones. 

In  concluding  this  chapter,  which  has  sought  to  give  the  general 
practitioner  an  elementary  statement  of  the  fundamental  principles 
of  orthodontia,  it  may  be  said  that  orthodontia  is  a  part  of  dentistry 
only  in  the  sense  that  it  has  to  do  with  the  teeth  and  mouth.  Dentistry 
is  the  study  and  treatment  of  the  diseases  of  the  mouth  and  their 
relation  to  the  health  of  the  individual.  Orthodontia  is  the  study  of 
the  development  of  the  denture  and  the  correction  of  deviations  from 
normal.  Dentistry  has  to  do  with  pathologic  processes,  orthodontia 
with  normal  developmental  processes.  Orthodontia  is  in  no  sense  a 
part  of  prosthetic  dentistry,  and  the  fundamental  principles  upon  which 
its  practice  is  based  are  not  involved  in  the  practice  of  dentistry.  If 
the  general  practitioner  can  grasp  this  idea  there  will  be  better  coopera- 
tion between  the  dentist  and  the  orthodontist  for  the  good  of  the 
patient  and  humanity. 


CHAPTER  XVI. 

ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY. 

By  KURT  H.  THOMA,  D.M.D. 

One  of  the  greatest  aids  in  examination  of  the  mouth  and  teeth, 
in  diagnosis  of  oral  lesions  and  in  the  discovery  of  obscure  defects 
and  abnormalities,  is  the  roentgen  method.  Its  usefulness  has 
increased  to  such  an  extent  that  today  it  is  a  necessary  part  of  modern 
dental  practice,  not  only  for  the  purpose  of  examination  but  also  to 
check  up  the  result  of  mechanical  procedures  and  surgical  treatment. 
The  diagnosis  from  a  roentgen  picture  alone,  however,  should  not 
be  relied  upon,  it  does  not  replace  any  of  the  other  means  of  exami- 
nation, but  should  be  considered  in  conjunction  with  other  methods 
of  diagnosis. 

The  value  of  the  diagnosis  made  from  a  roentgen  picture  depends 
of  course,  entirely  upon  correct  interpretation  and,  therefore,  on  the 
experience  and  skill  of  the  roentgenologist.  It  would  seem  advisable, 
on  this  account,  for  the  general  practitioner  to  refer  his  patient  to 
the  roentgen  specialist,  who  would  naturally  have  a  much  wider 
experience  and  a  specialized  training  in  this  branch  of  dentistry. 
On  the  other  hand  the  specialist  cannot  always  have  a  full  knowledge 
of  the  problem  which  is  referred  to  him,  and  he  cannot,  therefore, 
always  produce  the  picture  best  suited  to  the  case  in  question.  There 
is  no  doubt  whatever  that  the  patient,  as  a  rule,  will  receive  greater 
benefit  if  the  dentist,  for  routine  work,  makes  his  own  roentgen 
pictures,  except  in  cases  of  an  extensive  nature  and  for  unusual  con- 
ditions requiring  extraoral  exposures.  A  roentgen  machine  large 
enough  to  take  good  dental  films  in  from  three  to  five  seconds  would 
therefore  be  sufficient  for  his  needs  and,  being  close  at  hand,  would 
lead  to  more  frequent  use  than  if  the  patient  had  to  be  sent  to  someone 
else.  The  possibility  of  taking  roentgenograms  promptly  when  the 
need  arises  and  of  getting  the  result  in  a  short  time  enables  the  dentist 
to  use  this  method  extensively  for  routine  work. 

ROENTGEN  NOMENCLATURE. 

There  are  a  great  many  roentgen  terms  in  use,  and  there  has,  so 
f9,r,  been  no  st9,nda,rdiza,tion  in  dental  literature.     In  this  book  the 

(075) 


676       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

terms  employed  are  those  which  have  been  adopted  by  the  American 
Roentgen-ray  Society,  October  1,  1913,  and  accepted  by  the  Journal 
of  the  American  Medical  Association.  The  Committee  on  Nomen- 
clature of  the  American  Institute  of  Dental  Teachers  also  recom- 
mends their  use: 

Roentgen  Ray. — A  ray  discovered  and  described  by  Wilhelm  Conrad 
Roentgen. 

Roentgenology. — ^The  study  and  practice  of  the  roentgen  ray,  as 
applied  to  medical  science. 

Roentgenologist. — One  skilled  in  roentgenology. 

Roentgenogram. — A  shadow  picture  produced  by  the  roentgen  ray 
on  a  sensitive  plate  or  film. 

Roentgenograph  (verb). — ^To  make  a  roentgenogram. 

Roentgenography. — ^The  art  of  making  roentgenograms. 

Roentgen  Diagnosis. — A  diagnosis  made  by  means  of  roentgeno- 
grams. In  addition  to  these  terms  the  following  words  have  been 
made  use  of,  the  three  latter  having  been  supplied  by  Dr.  Ottolengui 
to  meet  a  long  felt  need  adequately  to  express  certain  properties:  - 

Radiahility. — ^The  property  of  an  object  to  transmit  the  roentgen 
ray. 

Radioparent  (Radioparency) . — Offering  no  barrier  to  the  roentgen 
ray. 

Radiolucent  (Radiolucency) . — Offering  slight  resistance  to  the 
roentgen  ray. 

Radiopaque  {Radiopacity) . — Impervious  to  the  roentgen  ray. 

THE  PRODUCTION  OF  ROENTGEN  RAYS. 

It  needs  but  little  practice  to  manipulate  a  roentgen  machine, 
detailed  instructions  being  always  furnished  by  the  manufacturers. 
The  way  to  produce  suitable  roentgen  rays  for  the  best  results  is 
soon  learned,  once  the  principle  is  thoroughly  understood.  The  first 
requirement  is  to  produce  the  most  suitable  type  of  ray.  The  quality 
of  the  rays  varies  according  to  the  vacuum  in  the  gas  tube  and  accord- 
ing to  the  temperature  of  the  filament  in  a  Coolidge  tube.  The  more 
perfect  the  vacuum  in  a  gas  tube  and  the  colder  the  filament  in  a 
Coolidge  tube  the  greater  the  resistance  offered  to  the  current  passing 
through  them.  A  tube  with  high  resistance  emits  "hard  rays"  while 
a  tube  with  low  resistance  generally  gives  what  is  called  "soft  rays." 
The  quality  of  the  rays,  therefore,  can  be  altered  at  will  by  changing 
the  resistance  of  the  tube.  In  the  gas  tube  (Fig.  530)  this  is  accom- 
plished by  letting  a  very  weak  current  pass  through  the  regulating 
chambers.    The  heat  generated  produces  gases  from  the  chemicals 


PRODUCTION  OF  ROENTGEN    RAYS 


677 


contained  therein,  which  pass  into  the  tube,  lowering  the  vacuum  and 
decreasing  the  resistance.  When  at  rest  the  vacuum  returns  to  its 
normal  state.  New  tubes  have  recently  been  constructed  which, 
together  with  other  improvements,  "come  back"  in  a  comparatively 


Fig.  530.— Gas  tube. 


Fig.  531. — Nitroken  tube. 


"•PI---"-' 


"^       -^!t=E=p-«|.- 


FiG.  532.— Coolidge  tube. 

short  time  to  their  original  vacuum,  which  is  very  much  higher  than 
in  the  old-style  gas  tube.  The  advantage  of  this  is  that  the  same 
tube,  by  proper  adjustment  before  each  exposure,  can  be  used  for  the 
production  of  either  hard  or  soft  rays.    The  regulator  is  said  to  be 


678        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

designed  so  that  overreduction  is  impossible.  An  example  of  this 
tube  is  the  Nitroken  tube  shown  in  Fig.  531.  In  the  Coolidge  tube 
(Fig.  532)  the  resistance  is  changed  by  heating  the  filament  in  the 
cathode  by  means  of  a  low-tension  current.  A  rheostat  is  used  to 
produce  the  change  which  affects  the  temperature.  At  a  certain 
temperature  of  the  filament  not  more  than  a  certain  number  of  milli- 
amperes  can  pass  through  the  tube,  regardless  of  how  high  the  output 
of  the  machine.  The  penetration  of  the  rays  increases  as  the  voltage 
is  increased  above  that  needed  for  the  current  value. 

Soft  rays  are  of  a  bluish-green  color  and  have  little  penetrating 
quality.  The  hard  rays,  which  have  a  much  greater  penetrating 
power,  are  suitable  for  bone  and  dental  work.  Too  much  penetration, 
however,  gives  a  picture  with  very  little  contrast,  a  fault  which  renders 
it  worthless  for  making  a  diagnosis  of  pathological  conditions,  which 
often  cause  only  a  slight  difference  in  the  radiability  of  the  tissues. 

METHOD  OF  TAKING  ROENTGEN  PICTURES  OF  THE 

TEETH. 

Roentgenograms  of  the  teeth  may  be  taken  by  either  the  extra-oral 
or  the  intra-oral  methods.  The  former  is  used  in  making  a  general 
survey,  so  as  to  get  an  idea  of  the  relation  of  the  neighboring  structures 
to  the  teeth  and  pathological  conditions  which  may  affect  them. 
Malposed  teeth,  extensive  bone  infection,  cysts  and  fractures  are  not 
infrequently  overlooked  when  only  small  dental  films  are  used.  The 
latter,  however,  show  details  of  the  teeth  and  alveolar  structures 
with  much  greater  accuracy  for  the  simple  reason  that  they  can  be 
placed  closer  to  the  tissue  which  is  to  be  investigated  and  because 
there  is  less  distortion  and  fewer  superimposed  shadows.  The  large 
size  (2|  X  3")  intra-oral  films  are  very  useful  for  more  extensive  pictures 
of  the  tissues  of  the  upper  jaw,  especially  in  the  anterior  region,  which 
cannot  be  clearly  reproduced  in  an  extra-oral  plate  or  film.  The  film 
is  placed  between  the  teeth,  as  far  back  as  possible,  with  the  sensitive 
side  directed  against  the  upper  jaw.  The  same  method  is  sometimes 
useful  for  the  lower  jaw,  especially  to  locate  calculi  or  foreign  bodies 
in  the  fioor  of  the  mouth.  For  the  latter  the  head-rest  of  the  chair 
must  be  so  adapted  that  the  patient  can  tip  the  head  way  back,  allow- 
ing sufficient  space  to  get  the  right  position  of  the  tube  in  front  of  the 
patient.  The  sensitive  side  of  the  film  is  placed  downward  toward 
the  part  to  be  roentgenographed.  The  small  dental  films  are  most 
generally  used  in  operative  dentistry.  A  new  dental  film  put  on 
the  market  recently  by  the  Buck  X-Ograph  Company,  St.  Louis, 
Missouri  can  be  recommended  very  highly.     It  is  far  superior  to 


METHOD  OF  TAKING  ROENTGEN  PICTURES  OF  TEETH     679 

the  original  Eastman  films  on  account  of  its  improved  method  of 
packing.  The  rounded  corners  make  it  possible  to  get  the  film  much 
closer  to  the  tissue,  and  when  once  placed  they  are  less  liable  to  slip 
from  their  original  position  than  the  Eastman  films. 

For  taking  the  roentgen  picture  the  patient  is  seated  in  the  chair. 
The  position  of  the  head  makes  no  great  difference,  although  it  is 
advisable  to  have  all  patients  in  the  same  position,  as  this  makes  it 
possible  to  develop  a  routine  and  so  get  uniform  results.  The  author 
always  has  the  patient  placed  so  that  the  lower  border  of  the  mandible 
lies  in  a  horizontal  plane. 


Elongation  of  picture 


-Ray 


Fig.  533 


Fig.  534 


Finding  the  Correct  Angle. — The  angle  at  which  the  rays  are  directed 
toward  the  object  is  of  the  greatest  importance  and  varies  consider- 
ably, not  only  for  different  teeth  but  for  different  patients.  The 
anatomic  make-up  of  the  inside  of  the  mouth  shows  many  variations, 
which  govern  the  placing  of  the  film.  If  the  patient  has  a  high  vault 
and  a  long  alveolar  process  the  film  can  be  placed  almost  parallel  with 
the  teeth  in  the  upper  jaw,  while  in  a  mouth  with  a  flat  palate  the  film 
may  be  at  a  decided  angle  to  the  teeth.  The  question  then  arises 
whether  the  rays  should  be  directed  vertically  to  the  teeth  or  to  the 
film.     Fig.  533  shows  the  result  of  directing  the  rays  vertically  to  the 


680'       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

object  (22  mm.),  producing  an  elongation  (24  mm.).  Fig.  534  shows 
the  rays  directed  vertically  to  the  film,  which  foreshortens  the  picture 
(IS  mm.).  The  rays  should  be  directed  vertically  to  an  imaginary 
plane  lying  exactly  half-way  between  the  plane  of  the  object  and  the 
plane  of  the  film.  This  gives  a  picture  of  natural  size  (22  mm.) 
(Fig.  535). 

This  principle  applies  to  all  single-rooted  teeth,  both  m  the  upper 
and  lower  jaws.  Multi-rooted  teeth  present  a  more  complex  problem. 
If  it  is  necessary  to  get  a  picture  showing  the  exact  condition  and 
correct  length  of  all  the  roots  it  is  often  necessary  to  take  two  or  three 
pictures  from  different  points  of  view.  A  picture  is  taken  of  each 
root,  the  angle  being  calculated  as  if  a  single  rooted  tooth  were  being 
roentgenographed.  In  addition  one  must  choose  a  direction  which 
prevents  overlapping.     The  teeth  which  present  the  greatest  diffi- 


Imaginary  plane 
Plane  offilnA  .  'Plane  of  object 


Fig.  535 

culties  are  the  upper  molars,  especially  the  first  and  second  molars. 
An  entirely  different  angle  is  necessary  for  the  palatal  root  and  the 
buccal  roots.  For  the  former  the  rays  are  directed  from  a  high  posi- 
tion of  the  tube,  which  gives  a  foreshortening  of  the  buccal  roots 
and  a  clear  picture  of  almost  the  entire  palatal  roots  (Figs.  536  and 
537).  The  buccal  roots  are  taken  with  a  more  horizontal  direction 
of  the  rays,  Figs.  538  and  539,  and  as  there  is  nearly  always  super- 
imposition  of  the  palatal  over  one  of  the  buccal  roots,  it  is  necessary 
to  take  one  picture  from  a  mesial  aspect  to  isolate  the  disto-buccal 
root,  and  one  from  a  distal  point  of  view  bringing  out  the  mesio- 
buccal  root,  in  case  it  is  not  fused  to  the  palatal  one  (Figs.  540  and 
541).  This  method  also  overcomes  another  anatomic  difficulty,  which 
often  occurs.  This  is  the  zygomatic  process,  which  may,  at  a  certain 
angle,  obscure  the  picture  (Fig.  542). 


METHOD  OF  TAKING  ROENTGEN  PICTURES  OF   TEETH     681 


The  upper  bicuspids  frequently  present  special  problems.  If 
roentgenographed  from  a  straight  buccal  aspect  it  frequently  appears 
as  if  there  were  but  one  root  canal  and  in  first  bicuspids  only  one 
root,  even  when  there  are  two  quite  distinct  and  divergent  ones. 
Generally  it  is  only  necessary  to  take  one  exposure  of  these  teeth  if  a 
slightly  mesial  direction  is  chosen  (Fig.  543).  Should  the  tooth,  how- 
ever, be  twisted  so  as  to  face  buccally  to  a  slight  extent  with  its  distal 
surface  it  will  be  found  that  a  disto-buccal  view  gives  a  better  picture. 


Fig.  536 


Fig.  537 


Fig.  538 


Fig.  539 


In  root-canal  work  the  operator  may  want  to  know  which  is  the  buccal 
and  which  the  lingual  root.  This  can  be  easily  determined.  If  the 
picture  is  taken  from  a  mesial  aspect  the  buccal  root  is  projected 
distally,  that  is,  nearer  the  second  bicuspid,  the  lingual  root  mesially, 
or  next  to  the  cuspid.  The  same  holds  true  for  the  root  canals  in  both 
teeth  (Fig.  544).  In  the  lower  jaw  the  technic  is  less  complicated. 
If  there  be  two  canals  In  a  molar  root  they  can  be  identified  by  means 
of  a  slightly  mesio-buccal  or  disto-buccal  direction  of  the  rays  exactly 
as  has  been  explained  for  the  upper  bicuspids. 


682       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


Fig.  540 


Direction  for 
Mesio-Buccal  root 


Direction  for 
Disto-Buccal  root 


Fig.  541 


\  Buccal  root 
\Lingual  root 


Fig.  542 


Fig.  543 


aK^s:i?aH«&"'.'S33»:!»r 


Fig.  544 


METHOD  OF   TAKING  ROENTGEN  PICTURES  OF   TEETH     683 

Length  of  Exposure. — ^Various  factors  govern  the  time  of  exposure. 
The  greatest  variations  are  due  to  the  type  and  output  of  the  machine 
and  the  make  of  tube.  It  is  therefore  a  matter  which  will  have  to  be 
ascertained  in  the  individual  case  and  may  be  determined  after  a 
little  experimentation.  It  will  be  found,  however,  that  after  a  while 
a  slight  increase  in  time  is  needed  unless  the  output  of  the  machine 
can  be  increased  to  overcome  a  decrease  of  the  efficiency,  which  comes 
with  the  use  of  the  induction  coil  and  the  aging  of  the  tube. 

The  milliamperage  of  the  current  passed  into  the  tube  is,  perhaps, 
the  most  important  factor.  The  time  of  exposure  can  be  decreased 
in  proportion  to  the  increase  of  the  milliamperage.  If  the  milliamper- 
age is  doubled  the  time  of  exposure  is  cut  down  one-half. 

A  variation  in  the  distance  of  the  target  from  the  plate  also  changes 
the  length  of  the  exposure,  the  change  being  in  proportion  to  the 
square  of  the  distance.  If,  for  example,  the  target  distance  should 
be  doubled  it  would  be  necessary  to  make  the  exposure  four  times  as 
long.  If  with  a  known  exposure  time  of  T  seconds  and  a  target  dis- 
tance of  Da  inches  a  new  target  distance  (Db)  be  chosen,  the  new 
exposure  time  (X)  can  be  calculated  by  the  following  equation: 


iW 


Variations  in  the  object  to  be  roentgenographed  have  to  be  con- 
sidered both  in  regard  to  changing  the  penetrating  quality  of  the  rays 
as  well  as  the  length  of  the  exposure.  Thick  and  dense  bone  needs 
greater  penetration,  a  higher  vacuum  in  the  tube  and  a  longer  exposure. 
It  skpuld  be  remembered  that  bone  varies  not  only  in  different  parts 
of  the  jaws  but  also  according  to  the  build  of  the  bony  frame  of  the 
individual.  In  old  people,  again,  we  find  a  higher  degree  of  calcifica- 
tion than  in  a  child. 

Further  factors  are  the  sensitiveness  of  the  roentgen  film  or  plate. 
The  different  makes  vary  and  there  are  both  fast  and  slow  films  on 
the  market.  The  latter  usually  give  better  results  because  slight 
mistakes  will  not  result  in  poor  pictures.  The  fast  films  permit  only 
slight  variations.  A  slow  film,  if  overexposed,  can  be  saved  in  the 
developing  process.  The  length  of  exposure  can  also  be  greatly 
decreased  by  the  use  of  intensifying  screens.  These  are  most  useful 
for  extra-oral  exposures,  especially  for  sinus  pictures.  The  new 
Eastman  double-coated  films,  which  are  used  for  head  work  in  the 
sizes  6x8  or  8  x  10  give  splendid  pictures  when  used  with  double 
screens  in  special  screen  holders  or  cassettes,  the  purpose  of  which 
is  to  bring  the  film  into  close  contact  with  the  screens.    The  action 


684        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


of  the  intensifying  screen  depends  upon  a  fluorescence,  which  is  pro- 
duced on  the  surface  of  the  screen  when  the  roentgen  rays  pass  through. 
The  actinic  hght,  which  the  screens  emit,  will  continue  to  act  on  the 
emulsion  even  after  the  exposure  is  completed.  With  double  screens 
the  length  of  exposure  can  be  decreased  to  at  least  one-fourth  of 
the  normal  time. 

The  effect  of  the  developing  must  also  be  considered  sometimes 
when  viewing  a  thin  picture.  It  may  appear  to  have  been  under- 
exposed when  the  real  fault  lay  in  the  development.  If  the  developer 
is  too  weak  or  too  cold  the  picture  will  not  be  as  good  as  could  be 
expected. 

Table  Giving  Time  of  Exposure. 


Object. 

Target 
distance 
in  inches. 

Resistance 
of  tube  back 
up  in  inches. 

Milliam- 
peres. 

Time  of 
expos- 
ure. 

Milliam- 

peres, 
seconds. 

For 

change 

in  target 

distance 

Db 

CooUdge  tubes 
figure  niilHam- 
pere  seconds. 

Letters     used     in 
equation 

Da 

V 

A 

T 

AxT 

AxT 

150 

Teeth  intra-oral    . 

15 

4 

30 

5 

150 

210 

1  AxT 

Jaws  intra-oral     . 

18 

4 

35 

6 

210 

260 

|AxT 

Jaws  extra-oral     . 

20 

4 

35 

7 

260 

P' 

|AxT 

Sinuses,    anterior- 
posterior 

22 

4i 

40 

8 

320 

320 
/22\  2 

i  AxT 

Development  of  Roentgen  Films. — The  films  are  developed  in  a  dark- 
room or  developing  cabinet.  Three  porcelain  bowls,  approximately 
five  inches  wide,  are  used  to  contain  the  developer,  the  iixing-bath 
and  the  rinsing  water.  Special  clips  (Fig.  545)  are  designed  to  use 
with  such  bowls.  They  facilitate  the  management  of  the  films  and 
make  it  possible  to  do  the  developing  without  immersing  the  fingers 
in  staining  chemicals.  A  clip  is  attached  to  each  film,  and  care 
should  be  taken  to  wash  the  clips  well  after  use.  The  developing 
fluid  is  best  prepared  from  powders,  which  are  manufactured  by 
concerns  like  the  Eastman  Company.  After  using  it  should  be 
poured  back  into  a  bottle  or  covered  over  to  prevent  free  access  of  air 
which  causes  oxidation.     It  is  a  good  plan  to  add  a  certain  amount 


METHOD  OF  TAKING  ROENTGEN  PICTURES  OF  TEETH     685 

of  new  developer  when  it  is  used  again,  as  the  chemicals  become  less 
active  with  age  and  use.  The  fixing  fluid  can  be  used  for  a  con- 
siderable length  of  time  and  may  safely  be  kept  in  an  open  bowl. 
The  films  must  be  well  rinsed  after  they  are  taken  from  the  developer 
before  being  transferred  to  the  fixing-bath.  The  temperature  of  the 
developing  fluid  affects  the  picture  considerably,  and  in  winter  it  is 
often  necessary  to  heat  it  slightly.  The  proper  temperature  is  about 
65°  F.  In  hot  weather  the  films  are  often  spoiled  because  the  emul- 
sion becomes  too  warm  and  melts  or  causes  blisters  to  appear  on  the 
surface  of  the  film  or  frills  on  the  margin.  It  is  often  advisable  to  use 
ice  water  for  the  washing  and  to  cool  the  solution.  The  author  prefers 
to  add  a  teaspoonful  of  alum  to  the  bowl  of  fixative,  as  well  as  into  the 
washing  water.     The  astringent  action  preserves  the  film. 


Fig.  545 

Roentgen  films  are  developed  in  the  same  manner  as  photographic 
negatives,  and  one  who  has  some  experience  in  photography  will  be 
able  to  save  a  good  many  pictures  which  have  not  been  quite  properly 
exposed.  The  inexperienced  operator  will  probably  at  first  get  most 
satisfactory  results  if  he  times  the  developing.  With  the  Eastman 
developer  for  dental  films  the  time  is  five  minutes,  after  which  the 
film  is  rinsed  in  clear  water  and  placed  in  the  fixing-bath  until  it  is 
entirely  transparent  when  held  to  the  light.  A  film  may  be  left  in 
the  fixing-bath  any  length  of  time  without  spoiling  it.  After  being 
fixed  the  film  should  be  washed  in  running  water  for  about  fifteen 


686        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

minutes  or  in  standing  water  for  an  hour,  during  which  time  the 
water  should  be  changed  several  times.  It  should  be  finally  hung 
up  by  the  hook  of  the  clip  until  dry,  when  it  is  finished.  The  drying 
process  may  be  hastened  by  putting  the  film  into  alcohol  for  a  few 
seconds  after  washing  it. 

There  are  various  opinions  as  to  the  appearance  of  a  perfect  roentgen 
negative.  Some  roentgenologists  like  them  very  dark,  so  as  to  neces- 
sitate holding  in  front  of  a  strong  light,  while  others  prefer  light,  but 
contrasting  pictures,  which  may  be  examined  in  ordinary  daylight,  as, 
for  example,  in  front  of  a  window.  The  author  prefers  the  latter 
type,  which  are  made  with  a  fairly  high  penetration,  but  backed  up 
by  enough  milliampere  seconds  to  give,  if  properly  developed,  an 
entirely  black  picture  of  the  radioparent  parts  and  a  very  translucent 
picture  of  the  parts  which  are  radiopaque. 

Recognition  of  the  Cause  of  Poor  Results. — It  is  generally  difficult 
for  the  student  to  determine  the  cause  of  a  poor  picture  and  to  find 
the  reason  for  his  failure  to  get  as  good  results  as  someone  else.  Quite 
frequently  he  blames  the  machine,  when  the  fault  is  clearly  a  matter 
of  technic.  When  trying  to  trace  the  cause  of  the  failure  it  is  best 
to  think  the  matter  over  carefully  and  to  consider  first  the  roentgen 
machine.  It  can  be  easily  and  quickly  tested  by  attaching  it  to  a 
tube  with  a  certain  back-up  and  taking  the  reading  of  the  milliampere- 
meter.  If  the  reading  is  less  than  usual  it  is  a  sign  that  the  output 
of  the  machine  has  been  decreased.  This  may  be  due  to  a  drop  in  the 
incoming  street  current  or  improper  functioning  of  the  interrupter 
or  induction  coil,  of  the  transformer  or  commutator,  or  other  parts, 
according  to  the  type  of  machine. 

The  tube  may  not  be  working  properly.  Gas  tubes  often  become 
freakish,  flitter  and  become  soft  during  the  exposure.  If  the  tube  is 
too  high  the  picture  will  not  show  enough  contrast  and  will  appear 
flat  (Fig.  546) .  If  the  tube  is  too  low  in  vacuum  there  is  not  enough 
penetration  of  the  hard  tissue  and  the  resulting  picture  will  be  thin 
(Fig.  547).  In  Fig.  548  the  patient  moved  and  the  picture  therefore 
is  not  very  clear. 

The  result  of  overexposing  or  underexposing  can  often  be  corrected 
by  proper  development.  Such  errors  are  due  to  exposing  the  film 
too  long  or  for  too  short  a  time  or  to  the  use  of  too  large  or  too  small 
a  milliamperage.  If  too  many  milliampere  seconds  are  employed 
and  the  picture  is  developed  the  normal  length  of  time  it  becomes 
very  black  and  may  be  so  dense  as  to  make  it  impossible  to  read  it, 
even  by  a  very  strong  artificial  light  (Fig.  549).  An  overexposed 
picture  develops  almost  instantly  and  can  only  be  saved  by  imme- 
diately diluting  the  developer  and  removing  the  film  fis  soon  ^s  it  is 


METHOD  OF  TAKING  ROENTGEN  PICTURES  OF  TEETH    687 


Fig.  546 


Fig.  547 


Fig.  548 


LJ 


Fig.  549 


Fig.  550 


Fig.  551 


\       ^ 


Fig.  552 


Fig.  553 


Fig.  554 


Fig.  555 


Fig.  556 


Fig.  557 


688       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

finished.  Overexposed  pictures  may  also  be  improved  by  the  use 
of  a  reducing  fluid,  such  as  can  be  bought  from  any  photographic 
supply  house.  If  too  few  milliampere  seconds  are  used  the  picture 
develops  very  slowly,  the  radioparent  parts  fail  to  become  black 
enough  and  if  the  development  is  forced,  that  is,  if  it  is  continued  much 
longer  than  usual,  the  negative  becomes  fogged  and,  after  being 
fixed,  often  has  a  yellowish  color  (Fig.  551).  Fig.  550  shows  a  normal 
roentgenogram  for  comparison. 

The  effects  of  development  have  already  been  described.  When 
the  developer  is  too  cold  the  result  is  a  very  thin  picture,  as  shown  in 
Fig.  552.  A  similar  condition  may  be  produced  by  a  developer  which 
is  too  old  or  by  underdevelopment  of  the  negative  (Fig.  553).  An 
overdeveloped  picture  looks  about  the  same  as  an  overexposed  one 
(Fig.  554). 

Other  poor  results  may  be  produced  by  movement  of  the  patient, 
vibrating  of  the  tube  or  slipping  of  the  film,  which  cause  the  picture 
to  become  indistinct,  losing  in  sharpness.  If  the  supply  of  films  is 
not  properly  stored  they  may  become  fogged  (Fig.  555) .  Films  should 
be  kept  in  a  lead  box  so  as  to  protect  them  from  the  rays  when  expo- 
sures are  being  made.  Daylight  will  not  affect  them  so  long  as  the 
packing  is  intact,  but  if  the  packing  becomes  torn,  or  if  light  is  allowed 
to  strike  the  film  through  carelessness  before  or  during  the  develop- 
ment the  picture  may  be  partly  defective,  fogged  or  entirely  spoiled 
(Fig.  556) .  Hot  weather  often  causes  the  emulsion  on  the  film  to  melt 
as  seen  in  Fig.  557. 


INTERPRETING  ROENTGEN  PICTURES. 

To  interpret  a  roentgen  picture  correc^"ly  is  the  most  important 
work  of  the  roentgenologist.  It  is  absolutely  necessary  that  he 
should  have  careful  training  and  special  knowledge  in  the  anatomy, 
histology  and  pathology  of  the  parts  he  is  to  examine.  If  he  is  a 
dental  roentgenologist  he  should  also  be  familiar  at  least  with  the 
various  dental  procedures  and  problems  of  dentistry  or  he  will  not 
be  able  to  cooperate  with  the  general  practitioner  sufficiently  to  give 
him  the  greatest  possible  benefit  from  his  services.  The  author 
cannot  forego  this  opportunity  to  lament  the  fact  that,  on  account 
of  inefficient  laws,  roentgen  laboratories  have  been  established  in 
most  of  the  larger  cities  by  laymen  who  not  only  make  roentgen 
pictures  but  also  supply  most  elaborate  reports.  Through  advertis- 
ing they  attract  patients  and,  worse  still,  otherwise  reputable  dentists 
who  refer  their  own  patients  to  them.     Such  practitioners  lower  the 


INTERPRETING  ROENTGEN  PICTURES  689 

standard  of  this  important  specialty  and  of  the  dental  profession  in 
general,  to  say  nothing  of  exposing  their  patients  to  false  advice,  based 
upon  the  opinion  of  an  ignorant  person. 

The  value  of  roentgen  diagnosis  depends  upon  correct  interpretation 
of  the  picture,  and  such  interpretation  can  only  be  made  from  a  good 
roentgenogram.  When  reading  a  picture,  however,  one  should  not 
forget  the  history  of  the  case  and  the  clinical  findings.  The  roentgen- 
ogram does  not  picture  disease.  It  only  records  changes  in  the  radia- 
bility  of  the  tissues,  which  have  been  brought  about  by  pathologic 
processes  as  well  as  surgical  and  medicinal  treatment.  Such  changes 
in  the  outlines;,  or  radiability,  are  correct  and  accurate  pictures  of 
grosser  structural  abnormalities;  finer  pathologic  conditions,  such 
as  those  seen  under  microscope,  cannot  be  recognized.  A  roentgen 
diagnosis  is,  therefore,  made  by  drawing  deductions  from  the  records 
made  by  the  roentgen  examination  and  the  roentgenologist  must 
become  proficient  in  associating  roentgen  signs  with  corresponding 
diseased  conditions.  In  a  roentgenogram  of  a  tooth,  for  example, 
the  picture  of  the  pulp  is  the  same,  whether  diseased  or  normal;  but 
if  a  dark  area,  indicating  decay,  is  shown  in  the  crown  of  the  tooth, 
and  if  this  area  comes  close  to  the  pulp,  one  may  suspect  pulp  disease. 
If  there  be  symptoms,  or  clinical  evidence  of  pulp  disease,  the  diag- 
nosis is  fairly  certain.  If,  in  addition  to  the  above,  the  picture  shows 
changes  around  the  apex  of  the  tooth  which  are  associated  with  infec- 
tion the  roentgenologist  can,  from  this  evidence  alone,  without  clinical 
indications,  draw  conclusions  which  lead  to  the  diagnosis  of  pulp 
disease. 

With  advances  in  technic  and  improvement  in  the  quality  of  the 
pictures  it  is  possible  to  demonstrate  finer  changes,  while  experience, 
careful  observation  and  systematic  study  of  a  large  number  of  similar 
cases,  as  well  as  comparison  of  roentgen  diagnosis  with  post-operative 
findings,  or  results  of  pathologic  examinations,  wall  make  it  possible 
to  carry  the  roentgen  diagnosis  to  a  finer  and  finer  point.  As  an 
example,  take  the  difi^erentiation  between  granulating  ostitis  and  a 
radicular  cyst.  In  both  cases  a  large  dark  area  may  be  shown  in 
the  film,  due  to  the  increased  radiability  of  the  area  w^here  loss  of  bone 
has  occurred.  Granulating  ostitis  is  distinguished  from  the  cyst  by  the 
appearance  of  the  outline  of  the  diseased  part  in  the  picture.  An 
irregular  margin  and  gradual  change  from  the  diseased  to  the  healthy 
part  indicates  ostitis,  while  a  clear  demarcation  of  definite  outline 
indicates  that  the  bone  itself  has  not  become  infected,  but  th,at  pres- 
sure absorption  has  occurred,  the  bone  cavity  having  been  reinforced 
by  a  dense  layer  of  normal  cortical  bone. 

A  roentgen  picture  is  a  record  upon  a  photographic  plate  or  film 
44 


690       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

of  the  radiability  of  tissues  through  which  the  rays  are  passed.  Soft 
tissue  is  very  radiolucent  and,  if  not  too  thick,  transmits  the  rays 
almost  as  well  as  air.  Bone  containing  a  large  percentage  of  calcium 
salts  is  very  much  less  radiolucent  and  enamel,  containing  almost  no 
organic  matter,  is  the  most  opaque  tissue  in  the  body.  Gold,  silver, 
lead  and  other  metals  are  almost  entirely  radiopaque.  Figs.  558,  559 
and  560  illustrate  changes  in  radiability.  Fig.  558  shows  the  normal 
molars  in  the  lower  jaw.  A  cavity  drilled  into  the  buccal  surface  of 
the  second  molar  increases  the  radiability  and,  since-the  obstruction  to 
the  passage  of  the  rays  is  decreased,  a  dark  shadow,  corresponding  to 
the  size  and  outline  of  the  hole,  appears  on  the  film  (Fig.  559) .  Metal 
placed  into  this  cavity  renders  the  area  impervious  to  the  roentgen 
rays  and  a  light  area  is  shown  in  the  picture  (Fig.  560). 

When  examining  a  roentgenogram  look  first  for  any  departure 
from  the  normal,  such  as  irregularity  in  size  or  outline  of  the  object 
or  any  change  in  its  normal  radiability.  It  is  of  great  advantage  to 
compare  the  part  under  observation  with  the  corresponding  part  on 
the  other  side  of  the  individual,  especially  when  there  is  any  doubt- 
when  the  appearance  of  the  condition  in  the  picture  is  not  pronounced 
and  not  readily  recognizable.  The  age  of  the  patient  should  also  be 
considered.  An  unerupted  tooth,  for  example,  is  a  normal  condition 
in  a  child,  while  in  the  adult  it  deserves  serious  consideration. 

Misconceptions  may  arise  from  distortion  of  the  angle  at  which 
the  picture  is  taken,  from  faulty  technic  in  the  development,  lack 
of  sufficient  knowledge  to  recognize  pictures  of  anatomic  structures, 
such  as  the  mental  foramen,  the  incisive  foramen  and  the  maxillary 
sinuses,  or  shadows  of  interposing  parts,  such  as  the  coronoid  process 
of  the  ramus  in  the  upper  third  molar  region  or  the  nose  and  nostrils 
in  front  of  the  upper  jaw.  The  picture  of  the  mental  foramen  may 
be  projected  so  that  it  comes  exactly  over  the  apex  of  a  bicuspid  root, 
appearing  the  same  as  would  an  apical  abscess.  The  mandibular 
canal,  however,  may  usually  be  traced  to  it,  which  helps  in  the  identi- 
fication. The  incisive  foramen  will  often  give  a  picture  superimposed 
over  that  of  the  apex  of  the  central  incisor,  especially  if  the  exposure  is 
made  from  a  slightly  lateral  angle.  A  new  film,  taken  from  a  difi^erent 
viewpoint,  will  usually  clear  up  all  doubt.  Beginners  often  mistake 
parts  of  the  maxillary  sinuses  for  extensive  diseased  conditions. 
Occasionally  a  case  is  referred  to  the  author  for  extraction  of  an 
upper  third  molar  tooth  root,  which  is  only  the  shadow  of  part  of 
the  ramus,  taken  from  a  fairly  vertical  direction  and  an  extremely 
(iistal  point  of  view, 


INTERPRETING  ROENTGEN  PICTURES 


691 


Fig.   558 


Fig.  559 


Fig.   560 


692       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

GENERAL  ROENTGEN  EXAMINATION  OF  THE  TEETH. 

The  method  of  examination  of  the  mouth,  as  practiced  by  the 
average  dentist  in  the  past,  is  thoroughly  inadequate.  As  a  rule, 
little  care  is  taken  to  consider  the  mouth  as  a  whole,  and  even  in 
localized  conditions  there  is  a  tendency  to  try  various  methods  of 
treatment  before  ascertaining  the  cause  and  the  exact  nature  of  the 
trouble.  In  a  general  way  we  may  say  that  we  have  two  kinds  of 
patients  to  examine,  those  who  come  with  a  definite  complaint  and 
those  who  want  a  general  examination  of  the  mouth.  It  is  with  the 
first  class  that  most  of  our  mistakes  are  made.  Take,  for  instance 
the  patient  who  wants  to  have  one  particular  tooth  extracted  because 
he  thinks  it  is  the  cause  of  some  systemic  disturbance;  the  folly  of 
extracting  this  one  tooth,  even  if  it  were  an  infectious  focus,  without 
thoroughly  investigating  the  condition  of  the  rest  of  the  teeth  is 
obvious.  It  is  extremely  unwise  to  jump  at  conclusions.  The  most 
proficient  diagnosticians  seldom  depart  from  a  systemic  plan  of  exami- 
nation, and  it  is  always  well  to  adopt  a  certain  routine  and  follow  it" 
in  every  case. 

It  is  advisable  to  inquire  into  the  patient's  general  health,  for  it  must 
be  borne  in  mind  that  the  teeth  are  not  isolated  organs  but  are  in 
immediate  relation  to  other  important  structures  and  closely  asso- 
ciated with  the  rest  of  the  body.  The  mouth  may  be  the  seat  of 
secondary  lesions  of  general  diseases,  such  as  the  eruptive  fevers, 
tuberculosis  and  syphilis,  and,  on  the  other  hand,  infectious  lesions 
in  the  mouth  may  be  the  primary  or  contributory  cause  of  somatic 
disturbances.  If  there  be  some  special  local  condition  of  which  the 
patient  complains  an  exact  history  should  be  taken.  The  mouth 
should  then  be  inspected,  the  condition  of  the  teeth  being  noted  first 
to  see  whether  they  are  healthy  or  neglected  or  whether  they  show 
signs  of  dental  work,  either  good  or  poor.  The  lips,  cheeks,  palate  and 
gums  should  be  examined  next.  Inflammatory  changes,  swellings  and 
fistulse  are  also  noted. 

Unless  it  is  evident  that  the  teeth  are  perfectly  healthy,  that  there 
are  no  large  fillings,  crowns  or  bridges,  a  roentgen  examination  is 
indicated.  A  patient  seen  for  the  first  time,  or  an  old  patient  whose 
teeth  have  never  been  roentgenographed,  should  have  a  routine 
examination — that  is,  pictures  of  all  the  teeth  (Figs.  561  to  577). 
If  this  is  systematically  carried  out  one  will  often  be  surprised  to 
find  definite  diseased  conditions  on  teeth  which  would  have  passed 
by  in  a  superficial  examination.  Indications  of  decay  under  fillings 
or  of  cavities  concealed  under  the  gums  are  frequently  discernible; 
unerupted  teeth  may  be  discovered  and  the  conditions  of  root  canal 


GENERAL  ROENTGEN  EXAMINATION  OF   TEETH  693 


Fig.  561 


Fig.  562 


Fig.  563 


Fig.  564 


Fig.  565 


Fig.  566 


Fig.  568 


Fig.  569 


Fig.  570 


604       ROENTGEN  DIAGNOSIS  iN  OPERATIVE  DENTISTRY 


fillings  and  status  of  devitali/.ed  teeth  are  disclosed.  Pus  pockets  due 
to  faulty  contact  points,  overhanging  fillings  and  other  mechanical 
irritations  become  clearly  visible,  together  with  their  cause,  and  in 


GENERAL  ROENTGEN  EXAMINATION  OF   TEETH 


(m 


pyorrhea!  conditions,  valuable  information  can  be  gathered  as  to  the 
amount  of  bone  destruction  and  deposit  of  serumal  calculus  in  the 
pockets.  The  roentgen  examination  is  of  further  value  in  leading  to 
the  discovery  of  other  conditions  which  cannot  be  definitely  demon- 
strated in  the  picture,  but  the  appearance  of  which  arouses  suspicion 
and  indicates  the  necessity  of  further  clinical  study. 

The  pictures,  after  completion,  should  be  mounted  on  a  film  mount 
designed  to  hold  the  entire  set,  so  that  the  views  of  the  whole  mouth 
can  be  seen  at  once  and  carefully  studied  before  the  patient  comes 

Dentist 
,Phj 
(File 


Original^  for   ,  pu„„i-:„n 
Copy     1    the  i  i-^'JP'"^*^ 


RIGHT  ^ 

FLOOR  0P\ 
ANTRUM 


LEFT 

FLOOR  OP 


Peiiapical-Alveolar  abscess     9. 

Canal  not  filled  10. 

Absorption  of  apex  ii. 

Apex  not  filled  12. 

Apex  filling  projects  13. 

Wire-Broach  in  canal  14. 

Perforation  of  canal  15. 

Irritation,  shell  crown  16. 


Irritation,  filling 
Pericementitis   (Lame  tooth) 
Alveolar  Absorption — pyorrhea 
Gingivitis 
Cavity 

Unextracted  root 
Fracture  of  root 
Unerupted  tooth 


17.  Supernumerary  tooth   25. 


18.  Impacted  tooth 

19.  Fracture  of  jaw 

20.  Process  fractured 

21.  Cementoma 

22.  Pulp  stone 

23.  Bone  "whorl" 

24.  Bone  cyst 


Bone  tumor 
Root  in  antrum 
Antral  empyema 
Apex  amputated 
Test  vitality 
Amputate  root 
Extraction  indicated 
Contact  point. 


(Dr.  Bryon  C.  Darling  Dental  Chart.) 


Copyrighted,  1918. 
Fig.  578 


The  Peck  Press,  New  York. 


in  again.  Records  should  then  be  made  on  an  examination  chart. 
The  trouble  with  the  majority  of  dental  examination  charts  is  that 
they  are  designed  to  indicate  only  the  condition  of  the  crowns  of  the 
teeth.  Darling's  dental  chart,  seen  in  Fig.  578,  may  be  used  by 
the  roentgenologist.  For  the  general  practitioner  of  dentistry  this 
chart  does  not  give  enough  room  for  the  recording  of  cavities  and 
fillings  in  all  the  tooth  surfaces.  The  Potter  chart  (Fig.  579),  which 
is  more  elaborate,  makes  it  possible  to  include  a  record  of  all  dental 
conditions.     This  chart  has  been  carefully  worked  out  by  Professor 


696       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


GENERAL  ROENTGEN  EXAMINATION  OF   TEETH 


mi 


698        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

William  H.  Potter  from  originals  of  historical  interest  by  Carabelli. 
The  back  of  the  chart  is  arranged  for  bookkeeping.  The  films  should 
be  kept  mounted  on  file  until  the  patient  is  finally  dismissed,  and 
at  each  visit  the  pictures  should  be  before  the  operator.  After  the 
work  is  completed  the  film  may  be  dismounted  and  filed  in  envelopes 
with  the  patient's  record. 

ROENTGEN  EXAMINATION  OF  THE  JAWS  IN   SOMATIC 

DISEASE. 

It  is  not  within  the  scope  of  this  contribution  to  discuss  the  relation 
of  oral  infections  to  somatic  disease.  There  is  no  reason  why  dental 
diseases  are  not  as  likely  to  be  the  cause  of  focal  infection  as  diseased 
tonsils,  infected  sinuses  or  gastro-intestinal  disturbances.  With  the 
roentgen  method  it  is  possible  to  discover  infections  in  the  jaws  which 
cause  no  symptoms  and  cannot  be  diagnosed  by  any  other  means,  but 
whether  such  infectious  lesions  in  the  mouth  are  the  original  foci,  or 
one  of  several  from  which  bacteria  have  migrated  to  other  organs; 
whether  it  is  only  absorption  of  toxins  from  these  foci  which  cause 
the  secondary  disease,  or  whether  the  dental  infections  and  the  sys- 
temic conditions  are  simply  coexistent  and  not  directly  related  to  each 
other,  are  questions  which  must  be  considered  separately  for  every 
case.  Also  positive  statements  cannot  be  made  with  absolute  certainty 
as  to  thie  probable  benefit  from  removing  the  focus,  since  the  secondary 
lesion  or  disease  may  be  of  such  long  standing  that  the  removal  of 
the  original  focus  has  but  little  effect,  the  secondary  lesion  not  having 
received  proper  attention,  or  the  tissue  changes  may  be  so  extensive 
that  restoration  to  the  normal  can  no  longer  be  expected.  The  best 
results  are  obtained  in  cases  of  short  duration  and  especially  in  those 
in  which  the  secondary  disease  is  due  to  a  toxemia  rather  than  to 
bacterial  migration.  After  finding  oral  lesions  in  a  patient  who  com- 
plains of  symptoms  caused  by  diseases  conceded  to  be  due  to  focal 
infection  the  patient  should  first  be  carefully  examined  by  an  internist. 
It  is  for  him  to  decide  the  nature  of  a  given  case  and  whether  focal 
absorption  of  toxins  or  bacteria  may  be  an  etiological  factor. 

Another  aspect  of  this  problem  is  the  question  as  to  whether  it  is 
perfectly  safe  for  an  otherwise  healthy  patient  to  retain  teeth  which 
on  account  of  their  chronic  character,  give  no  local  disturbance,  but 
which  show  infectious  processes  at  the  ends  of  the  roots  when  roentgen- 
ographed.  While  there  is  little  doubt  in  most  cases  as  to  what  should 
be  done  with  badly  infected  teeth,  there  are,  nevertheless,  cases  in 
which  we  should  like  to  recommend  and  try  more  conservative  methods 
if  we  could  be  sure  that  no  absorption  was  taking  place.     In  cases  of 


ROENTGEN  EXAMINATION  OF  JAWS  IN  SOMATIC  DISEASE      699 

long  standing,  in  which  apical  necrosis  and  absorption  are  discovered 
in  the  roentgen  picture,  indicating  clearly  that  Nature  wants  to  elimi- 
nate such  an  obnoxious  foreign  body,  extraction  is  indicated  from  a 
purely  dental  point  of  view.  No  one  w^ho  has  studied  the  tooth  and 
bone  pathology  of  old  pus-soaked  teeth,  or  who  has  experienced  the 
odor  of  one  which  has  been  removed,  would  ever  hesitate  to  recom- 
mend extraction  simply  for  the  sake  of  cleanliness.  But  in  cases 
of  short  standing,  especially  in  younger  patients,  treatment  and 
retention  of  the  tooth  would  seem  advisable  if  the  roentgenographic 
indications  are  favorable  to  root-canal  work.  Two  tests  have  recently 
been  used  by  the  author,  with  the  kind  cooperation  of  Dr.  Cotton, 
of  the  New  Jersey  State  Hospital,  and  Dr.  Charles  Lawrence,  of 
Boston,  to  demonstrate  whether  or  not  products  of  bacterial  activity 
have  been  absorbed.  Dr.  Cotton^  recommends  the  complement- 
fixation  test  for  streptococci  for  this  purpose,  with  which  he  has 
made  extensive  experiments.  The  skin  test,  as  used  for  proteid 
poisoning,  is  more  readily  available,  and  if  it  continues  to  prove 
reliable  when  verified  by  the  complement-fixation  test  and  bacterio- 
logical study  of  the  tooth  roots  it  will  be  of  the  greatest  value. 

The  most  common  oral  diseases  from  which  absorption  takes  place 
are  alveolar  abscesses,  pus  pockets,  pyorrheal  infections,  infections 
around  impacted  teeth,  as  well  as  more  extensive  bone  infections  in 
the  jaws,  such  as  ostitis,  osteomyelitis  and  infected  cysts.  A  sys- 
tematic roentgen  examination  of  the  teeth  and  jaws  is  necessary  in  all 
these  conditions,  and  with  few  exceptions  a  complete  set  of  dental 
films  should  be  taken. 

The  case  of  Mr.  G.  is  a  good  illustration:  he  complained  of  pain 
in  his  back  and  shoulders,  which  incapacitated  him  for  w^ork,  as  he 
was  a  chauffeur.  Roentgen  examination  of  the  shoulders  and  spine 
revealed  no  bony  changes,  which  led  to  the  conclusion  that  the  disease 
was  of  recent  standing.  He  had  a  careful  physical  examination  and 
no  cause  was  found  to  which  his  trouble  might  have  been  attributed. 
A  complement-fixation  test  of  the  blood  showed  a  3+  reaction  to 
hemolytic  streptococci,  3+  to  Streptococci  viridantis  and  3+  to  the 
colon  bacillus.  The  skin  test  reacted  positively  to  hemolytic  strepto- 
cocci. Streptococci  viridantis  and  pneumococci.  No  skin  test  was  made 
for  the  colon  bacillus.  Roentgen  pictures  were  taken  of  all  the  teeth, 
which  showed  many  abscesses,  as  seen  in  Figs.  580  to  589.  The  left 
upper  first  and  second  molars,  the  left  lower  first  and  second  molars, 
the  right  upper  central  and  lateral  incisors  and  the  first  molar  and 
the  right  lower  first  and  second  molars  were  extracted.     Pure  cultures 

1  Cotton,  Henry  A. :  The  Relation  of  Oral  Infection  to  Mental  Diseases,  The  Journal 
of  Dental  Research,  vol.  i,  No.  3,  p.  269. 


700       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


Fig.  580 


Fig.  581 


Fig.  582 


Fig.  583 


Fig.  584 


Fig.  585 


e-i-} 


i    4 


Fig.  586 


Fig.  587 


I 


L'J 


Fig.  588 


Fig.  589 


ROENTGEN  EXAMINATION  OF   THE   TEETH 


701 


of  Streptococci  viridantis  and  hemolytic  streptococci  were  obtained. 
The  patient  improved  very  rapidly,  so  that  he  was  able  to  go  to  work 
very  soon,  and  is  now  driving  a  truck. 

ROENTGEN  EXAMINATION   OF  THE  TEETH  IN  DISEASES  OF  THE 
MAXILLARY  SINUSES. 

Maxillary  sinusitis  in  its  various  forms  is,  according  to  Brophy, 
in  about  75  per  cent,  of  the  cases  due  to  diseases  of  the  teeth.  Acute 
infections   may   be  caused  by  careless  instrumentation  (Fig.  591), 


Fig.  590 


Fig.  591 


Fig.  592 


Fig.  593 


or  pushing  of  an  infected  root  into  the  antrum.  Chronic  abscesses 
on  the  upper  teeth  very  frequently  cause  chronic  infection  of  the  antra, 
with  polypoid  degeneration  of  the  mucous  membrane.  This  condi- 
tion often  develops  without  the  patient's  knowledge  and  is  discov- 
ered only  in  routine  examination.  If  large  abscesses  are  seen  in  the 
roentgen  pictures  of  the  upper  molars  and  bicuspids,  as  shown  in  Figs. 
590  to  592,  sinus  disease  should  always  be  considered  as  a  possibility. 
Roentgen  pictures  of  the  head  should  be  taken  for  investigation  of  the 
sinuses  (Figs.  594  and  595),  and,  on  the  other  hand,  in  cases  of  sinus 
symptoms  or  sinus  disease  the  teeth  should  not  be  neglected  and  their 


702        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

condition  must  be  investigated  roentgenographically.  Maxillary  sinu- 
sitis caused  by  a  tooth  and  cured  by  its  extraction  is  illustrated  in  the 
following  case :  The  tooth  in  question,  a  right  upper  bicuspid,  had  been 
devitalized  for  several  years  on  account  of  an  exposure  made  when  pre- 
paring the  tooth  for  a  cohesive  gold  filling.  About  one  year  ago  a 
roentgenogram  was  taken,  which  showed  a  very  slight  bone  infection. 
The  root  canal  was  treated  experimentally  by  various  modern  methods 
and  then  filled  under  strict  asepsis.    Later  a  bridge  was  attached  to  the 


Fig.   594 


tooth,  which  became  slightly  tender,  and  one  morning  three  months 
later  a  fulness  and  throbbing  sensation  was  felt  in  the  region  of  the 
right  maxillary  sinus  when  stepping  hard  arid  a  small  amount  of 
gelatinous  substance  was  discharged  through  the  right  nostril.  An 
anterior-posterior  roentgen  picture  taken  the  same  day  (Fig.  594) 
showed  the  right  sinus  to  be  dense,  and  on  transillumination  it  was 
entirely  dark.  The  tooth  shown  in  Fig.  593  was  extracted  at  once  and 
a  probe  passed  into  the  alveolar  socket,  which  showed,  however,  that 


ROENTGEN  EXAMINATION  OF   THE   TEETH 


703 


there  was  no  opening  through  the  floor  of  the  antrum.  No  further 
treatment  was  resorted  to;  the  symtoms  disappeared  and,  after  seven 
weeks,  the  sinus  was  clear  on  transillumination  and  in  the  roentgen 
picture  (Fig.  595). 


Fig.  595 


ROENTGEN  EXAMINATION  OF  THE  TEETH  IN  TRIFACIAL 
NEURALGIA. 

The  extensive  area  of  distribution  of  the  trifacial  nerve  and  its 
frequent  communications  with  other  cranial  nerves  and  the  sympathetic 
system  explains  the  clinical  manifestations  that  pa;in  and  irritation 
originating  from  some  dental  or  oral  cause  may  be  referred  to  very 
distant  parts  of  the  face  and  head,  including  the  ear  (otalgia  dentalis), 
the  eye,  the  nose  and  accessory  sinuses.  Such  pain  may  be  continu- 
ous, intermittent  or  periodic;  it  may  be  intense,  sharp,  throbbing  or 
dull,  and  it  may  be  a  sensation  of  obscure,  indefinable  pressure.  It 
sometimes  results  in  more  serious  nervous  disorders,  such  as  insomnia, 
melancholy  and  epilepsy. 


704       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

The  suffering  that  goes  with  these  conditions  is  often  intense,  and 
if  of  sufficient  duration  wears  the  patient  out.  The  cause  may  be 
difficult  to  ascertain  and  the  condition  calls  for  a  careful  study  with 
temperature  and  electrical  tests  as  well  as  painstaking  roentgen 
examination  both  of  the  entire  side  of  the  affected  jaws  and  the  teeth. 
Frequent  etiologic  factors  are  impacted  and  unerupted  teeth,  obscure 
pericemental  infections  and  affections  of  the  dental  pulp,  such  as 
irritation  from  improperly  fitting  bridges,  poor  fillings,  pulp  nodules 
(Fig.  596)  and  infection  from  decay  starting  either  underneath  the 
gum  or  continuing,  on  account  of  insufficient  sterilization,  after  the 
tooth  has  been  filled.     An  illustration  is  to  be  found  in  the  follow- 


FiG.  596 


Fig.  597 


Fig.  598 


ing  case  report.  Mrs.  V.  G.  L.  had  attacks  of  neuralgia  on  the  left 
side  of  the  face  at  intervals.  For  three  days  she  had  been  in  severe 
pain,  which  was  especially  located  in  the  ear  and  zygomatic  region. 
Roentgen  examination  (Fig.  597)  showed  a  large  radiolucent  area 
also  a  radiolucent  area  indicating  infection  at  the  apex  of  the  tooth. 
From  these  findings  we  conclude  that  the  pulp  is  diseased.  The 
operative  findings  revealed  a  pulp  which  was  necrotic.  In  another 
case  the  cause  was  found  in  the  upper  jaw.  Miss  R.  had  had  periodic 
headaches  in  the  back  of  the  head  for  several  years.  They  were 
quite  severe  and  always  on  the  right  side.  Sometimes  the  whole  half 
of  the  head  would  ache.     Roentgen  examination  (Fig.  598)  showed 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DLSEASES       705 

infection  of  the  right  upper  first  and  second  molars,  with  formation  of 
a  small  cyst,  also  an  unerupted,  impacted  third  molar.  The  pressure 
exerted  by  this  tooth  caused  the  well-illustrated  tipping  of  the  second 
molar.  A  frontal  plate  of  the  sinuses  was  negative.  Extraction  of  the 
three  molars  was  decided  upon,  and  during  the  operation  the  antrum 
was  opened  and,  after  u-rigation,  closed  with  sutures.  The  treatment 
relieved  the  symptoms. 

SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES. 

It  has  already  been  stated  that  a  roentgenogram  is  not  a  picture  of 
disease  but  a  record  of  the  changes  in  the  radiability  of  the  tissues, 
brought  about  by  pathologic  processes  or  surgical  interference.  In 
interpreting  a  roentgen  picture  the  history  and  clinical  manifesta- 
tions should  also  be  considered,  as  they  often  will  be  of  great  help. 
One  of  the  best  means  of  learning  to  read  roentgen  pictures  is  by 
carefully  studying  typical  illustrations  in  a  text-book,^  which  are 
reproduced  with  the  full  history,  symptoms  and  clinical  signs,  patho- 
logic report  and  findings  during  and  after  the  operation  or  treatment. 
The  purpose  of  this  chapter,  therefore,  is  to  show  the  reader  such 
typical  cases,  giving,  if  possible,  photographs  of  specimens  of  similar 
pathologic  conditions  to  illustrate  how  the  disease  affects  the  tissue 
and  its  radiability. 

Although  this  contribution  is  to  be  restricted  to  the  roentgenology 
of  conditions  which  concern  operative  dentistry  the  author  intends  to 
include  such  lesions  and  diseases  as  are  closely  associated  with  the 
teeth.  The  operator  should  be  familiar  with  their  pathology  and 
diagnosis,  so  as  to  be  able  to  differentiate  them  from  simpler  affections 
of  the  teeth,  recognizing  them  early  and  advise  the  patient  in  time. 
For  example,  large  cysts  are  frequently  treated  with  root-canal  medi- 
cation and  an  extensive  osteomyelitis,  as  pyorrhea. 

Abnormal  Dentition. 

Irregular  Eruption. — If  temporary  teeth  decay  early  and  become 
abscessed,  or  if  they  are  retained  too  long,  it  is  advisable  to 
investigate  the  progress  of  development  and  the  size  of  the  per- 
manent teeth  by  means  of  roentgen  pictures.  The  permanent  teeth 
may  be  prevented  from  erupting  on  account  of  impaction  of  the 
temporary  teeth.  In  the  case  illustrated  by  Fig.  599,  a  child,  aged 
twelve  years,  lacked  the  second  bicuspid  in  the  lower  jaw.  No  tem- 
porary second  molar  could  be  seen,  but  part  of  the  tooth  was  visible 

1  Thoma,  K.  H. :  Oral  Roentgenology,  Boston,  M.  C.  Cherry. 
45 


706       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


through  a  perforation  in  the  gum,  which  had  the  appearance  of  show- 
ing a  broken-down  root.  Roentgen  examination  showed  the  entire 
crown  of  the  second  temporary  molar  impacted  between  the  first 
molar  and  the  first  bicuspid.  Its  roots  had  been  absorbed,  but  its 
retention  prevented  normal  eruption  of  the  second  bicuspid.  A 
similar  condition  is  shown  in  another  case  (Fig.  600).  A  girl,  aged 
twelve  years,  had  a  temporary  molar  which  was  entirely  under  the 


Fig.  599 


Fig.  600 


gum,  impacted  between  the  two  permanent  teeth.  Its  roots  showed 
signs  of  resorption,  but  the  second  bicuspid  was  mal-shaped  and 
showed  only  rudimentary  development. 

Misplacement  of  a  tooth  germ  is  frequently  the  cause  of  permanent 
teeth  not  erupting.  In  the  case  shown  in  Fig.  601  a  space  was  held 
open  for  the  permanent  cuspid  for  a  long  time  until  a  roentgenogram 
showed  it  to  be  entirely  out  of  position. 


Fig.  601 


Fig.  602 


Sometimes,  however,  the  permanent  teeth  are  entirely  missing.  A 
large  roentgen  picture  should  always  be  taken  to  make  sure  they 
have  not  migrated  to  a  position  outside  the  realm  of  the  small  dental 
film.  In  the  case  shown  in  Fig.  602,  a  child,  aged  fourteen  years,  the 
second  temporary  molar  was  retained,  while  all  the  other  bicuspids 
had  erupted.  The  roentgen  picture  showed  slight  resorption  at  the 
root  apices  and  absence  of  the  permanent  tooth  which  should  take 
its  place, 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       707 

In  congenital  absence  of  temporary  teeth  the  permanent  ones 
may  be  missing  also.  In  the  case  of  a  boy,  aged  twelve  years  (Fig. 
603),  the  temporary  lateral  incisor  had  never  come  through.  By 
means  of  roentgen  diagnosis  it  was  found  that  not  only  the  temporary 
but  also  the  permanent  lateral  was  entirely  missing. 

If  the  temporary  tooth  is  present  and  is  retained  it  is  important  to 
know  whether  its  roots  have  become  absorbed  or  whether  they  show 
a  normal  condition.  The  author  has  seen  healthy  temporary  teeth 
with  well-shaped  roots  and  vital  pulps  in  patients  up  to  the  age  of 
forty. 


Fig.  603 

Artificial  Eruption. — Many  times,  especially  in  younger  people,  un- 
erupted  teeth  can,  in  favorable  cases,  be  erupted  artificially.  iVfter 
locating  the  exact  position  of  an  unerupted  tooth  by  the  roentgen 
methods  the  gum  is  incised  and  the  bone  overlying  the  tooth  removed, 
so  that  part  of  the  enamel  is  exposed.  The  tissue  is  then  cauterized 
and  packed  w^ith  rubber  tissue.  After  forty-eight  hours  the  packing 
can  be  removed  and,  if  proper  care  is  taken,  without  causing  any 
bleeding.  A  small  loop  of  platinum  wire  is  then  cemented  into  a 
hole  drilled  into  the  tooth.  To  this  may  be  attached  an  extension 
from  the  orthodontia  arch  wire,  by  means  of  which  gradual  force  is 
applied  until  the  tooth  is  moved  to  its  normal  position.  To  illustrate 
what  may  be  done  the  following  case  of  Dr.  iVlfred  Rogers'  serves  as 
an  illustration.  Fig.  604  shows  the  condition  two  days  after  the 
author  had  operated  on  an  unerupted  cuspid,  the  appliances  having 
just  been  attached.    After  nine  months  the  tooth  was  almost  in  its 


708       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


Fig.  604 


Fig.  605 


Fig. 


Fig.  607 


Fig. 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DhSEASES       709 

proper  position,  except  that  a  certain  amount  of  rotating  was  still 
necessary.  The  condition  at  this  time  is  shown  in  Fig.  ()05.  Not 
always,  however,  can  such  successful  results  be  obtained.  In  the 
case  illustrated  by  Fig.  606,  which  shows  the  condition  before  treat- 
ment and  Fig.  607,  which  shows  the  tooth  after  attachment  of  the 
appliances,  constant  force  was  applied  for  ten  months  with  apparently 
no  result  whatever,  as  seen  in  Fig.  608.  The  cuspid  is  still  in  its  old 
position,  probably  firmly  impacted  over  the  resorbed  surface  of  the 
lateral.  Examine  also  the  apices  of  the  roots  of  the  other  incisors. 
They  are  all  vital,  the  condition  of  the  roots  being  due  to  incomplete 
formation. 


Fig.  609 


Fig.  610 


Replacement  by  Bridge-work. — If  bridge-work  is  contemplated  to 
replace  a  missing  tooth,  the  history  of  which  is  not  entirely  known, 
it  is  better  to  ascertain  by  means  of  a  roentgen  picture  whether  it  is 
embedded  in  the  jaw.  This  precaution  may  save  the  patient  con- 
siderable trouble.  In  the  case  of  an  adult  patient  a  bridge  was  con- 
structed by  her  dentist  to  replace  a  cuspid  which  was  missing.  Some- 
time later  the  lateral  incisor  began  to  get  very  sore,  with  a  feeling  of 
pressure  in  the  anterior  part  of  the  jaw  on  that  side.  The  dentist 
advised  removing  the  pulp  in  the  lateral,  or  removal  of  the  bridge, 
without  further  investigating  the  real  cause  of  her  condition.  The 
trouble  is  clearly  shown  in  Fig.  609  to  be  due  to  an  unerupted  cuspid. 
The  effort  of  the  cuspid  to  erupt  resulted  in  pressure  on  the  root  of 
the  lateral  incisor.  Another  case  is  shown  in  Fig.  610.  The  patient 
said  that  the  central  incisor  felt  sore  from  time  to  time.  Roentgen 
examination  showed  an  unerupted  cuspid  pressing  against  the  root 
of  the  central  in  its  effort  to  grow  out  of  the  jaw. 


710       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

Unerupted  and  Impacted  Molars.— The  third  molars  being  the  last 
teeth  to  take  their  position  in  the  dental  arch  are  most  frequently 
found  to  be  unerupted  and  impacted.  This  is  principally  due  to 
underdevelopment  of  the  jaws,  which  fail  to  grow  large  enough  to 
accommodate  all  the  teeth.  Their  position  in  the  jaw  varies  greatly. 
They  may  be  partly  erupted  but  prevented  from  entire  eruption  by 
a  bulging  distal  surface  of  the  second  molar  or  the  ascending  ramus. 
At  other  times  they  may  be  entirely  unerupted.  Unerupted  teeth 
are  either  in  upright  position,  mesially  or  distally  inclined,  but  are 
sometimes  at  a  great  distance  from  their  proper  places.  They  may 
be  found  in  any  part  of  the  ramus  or  maxillary  bone,  as  illustrated  in 
two  cases  in  the  author's  text-book  on  Oral  Roentgenology,^  first  edition, 
Figs.  33  and  189. 

Unerupted  molars  are  frequently  the  cause  of  obscure  feelings  of 
pressure  and  neuralgic  symptoms,  which  may  be  continuous,  inter- 
mittent or  periodic.  The  pain  may  be  intense,  sharp,  throbbing  or 
dull,  and  may  be  referred  to  distant  parts  of  the  face  and  head.  Local 
conditions,  especially  infection,  are  often  associated  with  partly 
erupted  teeth.  After  the  gum  has  been  pierced  by  the  cusps  of  the 
tooth,  an  orifice  is  made  which  allows  food  and  bacteria  to  enter 
between  the  enamel  of  the  tooth  and  its  overlying  soft  tissue.  The 
condition  frequently  is  aggravated  by  biting  on  the  inflamed  tissue 
during  mastication.  The  inflammation  then  spreads  to  the  neigh- 
boring tissue,  causing  a  trismus  of  the  muscles  of  mastication,  so  that 
the  mouth  can  be  opened  but  very  little.  The  submaxillary  lymph 
glands  become  enlarged  and  tender,  with  marked  swelling  on  the  side 
of  the  face  and  neck.  One  sequel  may  be  pharyngitis,  sometimes 
even  leading  to  the  formation  of  a  pharyngeal  abscess,  simulating  a 
peritonsilar  abscess.  In  the  case  of  Mr.  R.  B.  T.  such  a  condition 
is  exemplified.  He  presented  a  history  of  repeated  trouble  with  the 
left  lower  third  molar.  The  last  attack  was  the  worst,  being  accom- 
panied by  large  swelling,  difficulty  in  swallowing,  trismus  of  the 
muscles  of  the  jaws  and  pus  discharge  around  the  tooth.  He  con- 
sulted a  laryngologist,  as  he  thought  the  primary  trouble  was  in  the 
throat.  Roentgen  examination  (Fig.  611),  however,  disclosed  an 
impacted  lower  third  molar  with  a  large  cavity  in  the  crown,  appar- 
ently involving  the  pulp  and  causing  an  extensive  infection  of  the 
surrounding  parts. 

Another  complication  occurs  if  pressure  exerted  by  the  impacted 
tooth  causes  absorption  of  part  of  the  second  molar.  A  good  example 
is  shown  in  Fig.  612.     The  patient  had  suffered  neuralgic  pains  for 

1  Thoma,  K.  H. :  Oral  Roentgenology,  Boston,  M.  C.  Cherry. 


SPECIAL  ROUMTGEN  STUDY  OF  DEMTAL  DISEASES       711 


several  weeks.    The  roentgen  picture  revealed  a  partly  erupted  upper 
third  molar,  which  caused  pressure  absorption  on  the  distal  surface 


Fig.  611 


Fig.  612 


of  the  second  molar  to  such  an  extent  that  khe  pulp  barely  escaped 
involvement. 

Roentgen  examination  is  the  most  valuable  means,  and  sometimes 
the  only  one,  by  which  unerupted  teeth  can  be  discovered.  The  size 
of  the  picture  should  be  such  as  to  include  the  entire  tooth  and 


Fig.  613 


a  considerable  portion  of  the  surrounding  structures.     A  roentgen- 
ogram which  shows  only  part  of  the  tooth  is,  of  course,  sufficient  to 


712        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

reveal  its  presence.  To  the  surgeon  who  must  remove  it,  however, 
such  a  film  is  useless,  for  he  needs  exact  information  as  to  the  number, 
size  and  shape  of  the  roots  and  the  position  of  the  tooth  and  its  rela- 
tion to  the  bone  of  the  ramus.  Fig.  613  shows  an  extra-oral  picture 
of  an  unerupted  upper  third  molar  impacted  under  the  distal  surface 
of  the  tooth  in  front.  Note  also  the  root  formation  of  the  third  molar 
in  the  lower  jaw.  Another  case  is  illustrated  in  Figs.  614  and  615. 
The  patient,  aged  nineteen  years,  suffered  for  several  years  with 
periodic  headaches,  especially  on  the  right  side  in  the  region  of  the 
frontal  sinuses,  with  indefinite  subjective  symptoms  of  pressure  in 
the  back  of  the  head.  At  times  the  pain  disappeared  entirely  and 
then  a  period  of  suffering  followed.  Roentgen  pictures,  showing 
unerupted  third  molar  teeth,  had  been  taken  two  years  before  the 
patient  presented  for  examination.  These  teeth,  however,  apparently 
did  not  exert  pressure  against  those  in  front  (Fig.  614),  and  were,  for 
this  reason,  considered  innocent.     Roentgen  examination  two  years 


Fig.  614 


Fig.   615 


after  the  first  plates  had  been  taken  (Fig.  615)  showed  that  the  lower 
molar  had  grown  into  a  position  which  one  would  not  have  expected 
from  the  position  shown  in  the  first  plate  (Fig.  614).  It  was  decided 
to  remove  all  four  third  molar  teeth,  which  resulted  in  complete  relief 
from  all  the  symptoms.  This  case  demonstrates  the  fact  that  pain 
is  often  caused  by  the  development  of  the  roots  of  the  teeth  against 
the  inferior  alveolar  nerve.  , ; 

Supernumerary  Teeth. — ^These  may  be  well-formed  teeth  or  in  rudi- 
mentary peg-shaped  form.  They  may  be  erupted  in  natural  position 
or  outside  the  dental  arch.  Fig.  616  shows  a  roentgen  picture  of  the 
jaw  of  a  girl,  aged  seventeen  years.  The  orthodontist  has  kept  open 
a  space  for  the  cuspid  which  was  slow  in  erupting.  A  picture  was 
taken  to  find  out  what  its  position  was.  The  roentgen  finding,  how- 
ever, showed  that  the  tooth  about  to  erupt  was  a  supernumerary 
bicuspid,  the  cuspid  being  unerupted  and  quite  a  distance  from  its 
normal  place.     In  another  case  a  small  rudimentary  molar  was  seen 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       713 

behind  the  second  molar.     The  roentgen  picture  revealed  a  fourth 
unerupted  molar  of  normal  size  (Fig.  617). 


Fig.  616 


Fig.  617 


Follicular  and  Dentigerous  Cysts. — Other  disturbances  of  normal 
dentition  of  a  more  serious  character  are  caused  by  abnormal  develop- 
ment of  a  tooth  follicle  during  the  developmental  stage  of  a  tooth. 
Instead  of  a  tooth  a  cyst  may  be  formed,  in  which  case  it  is  called  a 
follicular  cyst.  Such  cysts  may  be  formed  from  the  enamel  organ 
without  the  development  of  a  tooth.  In  other  cases,  however,  one 
or  more  teeth  may  be  found  in  the  cyst,  when  it  is  called  dentigerous. 
Sometimes  only  masses  of  calcified  tooth  particles  are  produced,  and 
these  may  be  composed  of  enamel,  dentin,  cement  and  dental  pulp. 
Occasionally  they  also  contain  bone.  Such  a  lesion  is  spoken  of  as  a 
cystic  odontoma.  Calcified  tissue,  however,  is  not  always  formed, 
and  microscopic  examination  may  show  a  mass  of  enamel  organs 
with  cylindrical  epithelial  cells.  Typical  ameloblasts  are  sometimes 
developed,  and  these  may  be  found  laying  down  enamel.  This  is 
called  a  cystic  adamantonoma. 

The  cyst  sac  is  usually  composed  of  a  fibrous  membrane  lined  by 
epithelium,  which  may  be  in  a  single  layer,  stratified  or  epidermoid 
in  character.  The  liquid  contained  in  the  sac  is  clear  and  straw- 
colored,  originating  principally  from  a  secretion  by  the  epithelial 
cells.  Cholesterin  crystals  are  usually  present,  and  if  infection  has 
taken  place  it  is  contaminated  by  pus. 

Roentgen  diagnosis  is  of  greatest  help,  as  there  is  often  little  clinical 
indication,  and  the  symptoms  may  be  very  misleading.  The  roentgen 
picture  also  gives  valuable  information  as  to  the  cause,  extent  and 
type  of  cyst  and  helps  in  determining  the  mode  of  operation.  Teeth 
in  dentigerous  cysts  can  be  located  fairly  accurately,  which  facilitates 


714       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

their  removal.  Extra-oral  exposures  or  large  intra-oral  films  should 
be  taken,  as  small  ones  seldom  cover  more  than  a  part  of  the  lesion. 
The  dark  area  representing  radiolucency,  due  to  absorption  of  bone, 
is  defined  by  a  light  line,  the  cortical  layer  of  bone  which  forms  the 
wall  of  the  bone  cavity. 

In  the  case  of  Si.  (Fig.  618),  a  man,  about  sixty-five  years  old,  the 
patient  complained  of  a  bad-smelling  fluid  escaping  from  a  sinus  in 
the  third  molar  region.  The  second  and  third  molars  were  missing. 
The  second  molar  had  been  extracted  a  short  time  before,  but  this 


Fig.  618 


did  not  improve  the  complaint.  Roentgen  examination  by  means  of 
a  small  dental  film  showed  a  dark  area  at  the  root  of  the  first  molar, 
but  no  impacted  tooth.  A  large  plate  was  then  taken  (Fig.  618). 
This  shows  a  large  dark  area  extending  to  the  lower  border  of  the 
mandible  and  almost  to  the  angle  of  the  ramus.  The  area  is  sur- 
rounded by  a  distinct  light  line,  the  typical  picture  of  a  cyst.  The 
third  molar  is  found  near  the  angle  of  the  jaw.  A  diagnosis  was 
made  of  dentigerous  cyst,  infected  from  the  mouth.  In  the  case  of 
W.  W.  (Fig.  619),  that  of  a  boy,  aged  nine  years,  the  following  history 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  .DISEASES       715 

was  given:  his  mother  first  noticed  a  swelhng  in  the  left  upper  side 
of  the  jaw  in  the  cuspid  region  about  one  year  previous  to  the  con- 
sultation.    She  thought  it  was  the  cuspid  about  to  erupt.     There 


Fig.  619 


Fig.  620 


Fig.  621 


was  no  pain  or  soreness.  A  little  later  the  left  upper  first  temporary 
molar  started  to  feel  tender.  It  was  filled,  treated  and  refilled  by  a 
dentist,  and  finally  fell  out.     Nearly  a  year  later  a  slight  swelling  on 


716        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

the  left  side  of  the  face  and  side  of  the  nose  was  noticed  by  his  physi- 
cian, who  referred  him  back  to  the  dentist,  from  whom  he  was  sent  to 
the  author.  Physical  examination  revealed  little  besides  the  swelling 
on  the  face.  The  alveolar  process  showed  no  signs  of  a  cyst.  Roent- 
gen pictures,  however,  showed  a  large  dentigerous  cyst  containing  an 
unerupted  cuspid,  apparently  encroaching  somewhat  on  the  maxillary 
sinus,  and  being  located  between  the  alveolar  process,  the  nasal  cavity 
and  the  palatal  process.  In  another  case,  that  of  a  boy,  aged  sixteen 
years,  the  patient  noticed  a  swelling  under  his  upper  lip  for  several 
months,  the  left  upper  central  and  lateral  incisors  being  somewhat 
tender  to  the  touch.  His  dentist  opened  the  left  upper  lateral  incisor, 
removed  the  pulp  and  treated  the  root  canal.  Whenever  the  root-canal 
dressing  was  changed  a  yellowish  fluid  escaped  through  the  tooth. 
The  treatments  failed  to  help  the  condition  and  the  gum  was  lanced 
several  times  without  result.  The  patient  was  sent  in  for  consulta- 
tion on  November  8,  1918,  at  which  time  a  roentgen  picture  (Fig. 
620)  was  taken  and  from  this  and  the  clinical  evidence  a  diagnosis  of 
cystic  odontoma  was  made.  Fig.  621  shows  a  microscopic  picture 
of  the  cyst  with  its  contents. 

Traumatic  Injuries  of  Teeth. 

Injuries,  especially  of  the  front  teeth,  are  a  frequent  occurrence  in 
children  and  occasionally  in  adults  with  accidental  injuries.  The 
teeth  may  become  dislodged  and  sometimes  are  forced  deep  into  the 
tissues.  A  case  of  the  latter  type  is  exemplified  in  the  following 
patient:  a  young  girl,  as  a  result  of  falling  down  stairs,  had  a  badly 
cut  lip  and  tongue.  No  teeth  could  be  seen  in  the  anterior  part  of 
the  upper  jaw.  The  roentgenogram  (Fig.  622)  shows  that  the  tem- 
porary incisors  were  driven  into  the  jaw,  the  permanent  teeth  escaping 
injury. 

Teeth  which  are  loosened  by  an  accident  may  be  fractured  or  only 
broken  out  of  the  process.  A  roentgen  picture  will  help  to  determine 
the  condition.  If  no  fracture  has  occurred  and  the  tooth  is  retained 
it  should  be  examined  from  time  to  time  to  find  out  whether  the  pulp 
remains  normal.  Fractures  of  teeth  sometimes  show  plainly  when 
roentgenographed,  especially  when  the  fracture  occurs  in  a  transverse 
direction  or  in  a  plane  vertical  to  the  film.  If  the  plane  of  fracture 
is  parallel  to  the  film  there  may  be  some  difficulty  in  making  a  correct 
diagnosis.  The  patient  whose  roentgen  film  is  shown  in  Fig.  623  was 
in  a  motor  cycle  accident.  The  upper  front  teeth  were  slightly  broken 
at  the  edges.  The  left  upper  incisor  was  very  tender  and  there  was 
a  slight  swelling  over  the  gum.     The  roentgen  examination  shows 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DLSEASES       717 

fracture  of  the  root.     The  small  radiolucent  area  at  the  apex  indicates 
the  beginning  of  an  apical  abscess. 

Another  case  is  shown  in  Fig.  624.  From  an  accident  the  bicuspid 
had  been  fractured  in  a  horizontal  plane,  as  can  be  seen  in  the  illus- 
tration, with  a  dark  area  indicating  bone  infection  surrounding  the 
site  of  the  fracture. 


N 


f      \        ^ 


Fig.  622 


Fig.  623 


Fig.  624 


Fig.   625 


Posts  of  crowns  and  bridge  abutments  are  sometimes  the  cause  of 
a  fractured  root,  as  illustrated  by  the  following  case:  the  patient 
whose  roentgen  ray  is  shown  in  Fig.  625  had  a  Richmond  crown  on 
a  second  bicuspid.  The  gum  was  inflamed  and  the  tooth  sensitive. 
Roentgen  examination  showed  that  the  post  had  caused  a  vertical 
fracture  of  the  roots. 

Dental  Caries. 

•  Cavities  in  the  incisors  and  occlusal  surfaces  of  the  posterior 
teeth  are  easily  recognized.  Proximate  cavities  in  molars  and 
bicuspids,  however,  are  frequently  overlooked  and  decay  under 
a  filling  often  cannot  be  recognized  before  considerable  harm  has 
resulted.    The  roentgen  method  has  not  yet  come  into  general  use  to 


718        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

find  obscure  cavities  in  routine  examination,  but  judging  from  inci- 
dental findings  in  systematic  search  for  infectious  lesions  it  might  be 
well  worth  while  to  use  the  roentgen  ray  for  this  purpose.     Decay 


Fig.  626 


Fig.  627 


under  fillings  and  crowns  of  various  types  may  escape  notice  in  the 
most  careful  instrumental  examination.  Its  timely  recognition  is,  of 
course,  of  greatest  value  not  only  in  cases  in  which  there  is  obscure 


Fig.  628 


Fig.  629 


pain,  but  particularly  to  prevent  the  infection  of  dental  pulps.  Caries 
is  recognized  in  a  roentgenogram  as  a  dark  area,  due  to  increased 
radiabib'ty,  which  is  due  partly  to  decalcification  of  the  dentin  by 


Fig.  630 


Fig.   631 


bacterial  ferments  and  partly  to  actual  loss  of  tooth  substance.  Fig. 
626  shows  a  roentgenogram  of  a  molar  tooth  with  a  large  cavity  at 
the  distal  surface.     Figs.  627  md  628  show  obscure  cavities  under 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       719 

fillings.  In  the  first  there  was  slight  pain  from  hot  and  cold  food;  in 
the  two  latter  a  neuralgic  pain  of  the  jaw,  caused  by  the  cavity  at 
the  distal  side  under  the  cervical  part  of  a  filling.  Fig.  629  shows 
a  crowned  first  molar  with  decay  at  the  cervical  margin  on  the  distal 
side. 

When  caries  extends  deep  into  the  tooth  substance  it  produces  a 
protective  reaction,  which  very  probably  is  also  called  into  activity  if 
large  fillings  are  inserted  without  an  insulating  layer  of  cement.  The 
irritating  action  of  the  infection,  as  well  as  chemical  and  thermal 
influences,  stimulate  deposit  of  secondary  dentin,  which,  of  course, 
decreases  the  size  of  the  pulp  chamber.  This  can  be  easily  recognized 
in  any  roentgen  picture  of  the  teeth.  Fig.  630  shows  upper  incisors 
with  large  cavities  at  both  sides.  The  pulps  have  receded,  due  to 
deposits  of  secondary  dentin,  filling  the  pulp  canal  in  the  crown  entirely. 
Fig.  631  shows  recession  of  the  pulp  in  an  upper  first  bicuspid,  due  to 
a  large  disto-occlusal  filling. 


Fig.  632 


Fig.   633 


Cavity  Fillings. 

Different  filling  materials  have  a  different  degree  of  radiability. 
Porcelain  cement  fillings  often  appear  the  same  in  a  picture  as  a 
cavity,  on  account  of  their  radiolucency.  Oxyphosphate  cements 
also  are  more  radiolucent  than  the  substance  of  a  tooth,  and,  there- 
fore, give  a  similar  picture.  Metal  fillings,  of  course,  are  com- 
pletely radiopaque  and  gutta-percha  offers  a  similar  barrier  to  the 
rays.  Fig.  632  shows  an  upper  central  incisor  with  a  gutta-percha 
root  canal  filling.  On  its  distal  side  a  porcelain  cement  filling  has  been 
inserted.  Compare  the  radiability  of  the  tooth  with  the  porcelain 
filling  and  the  gutta-percha.  Fig.  633  shows  upper  incisors  with  two 
gold  fillings  in  each  central  and  another  gold  filling  in  the  mesial 
surface  of  the  right  lateral  incisors. 

Every  dental  roentgenologist  could  produce  a  large  number  of  films 
showing  poor  gold,  amalgam,  cement  and  gutta-percha  fillings  and 
gold  inlays.     Large  overhangs  injuring  the  peridental  mernbrane  and 


720 


ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


alveolar  bone,  as  well  as  lack  of  contact  points  giving  occasion  for  the 
formation  of  so-called  food-pockets,  are  the  most  frequently  observed 
evils.     A  collection  of  such  cases  is  shown  in  Figs.  634  to  639. 


Fig.  634 


Fig.  635 


The  first  film  (Fig.  634)  shows  amalgam  fillings  with  rough  over- 
hangs extending  down  between  the  teeth,  causing  periodontal  inflam- 
mation and  pockets.     Fig.  635  shows  lack  of  contact  points  between 


Fig.  636 


Fig.  637 


the  two  molars  and  roughness  of  the  filling  in  the  second  molar  at 
the  cervical  margin.  Fig.  636  shows  an  extensive  overhang  at  the 
mesial  side  of  a  lower  second  molar,  which  was  the  cause  of  an  inflam- 


FiG.  638 


Fig.   639 


matory  reaction  of  the  investing  tissues.  In  Fig.  637  am'algam  fillings 
of  ragged  outline  are  shown,  with  decay  under  the  mesial  portion  of 
the  fillings,  both  in  the  first  and  second  molar,  as  well  as  lack  of  proper 
contact  points.     A  gold  inlay  is  shown  in  Fig.  638  in  an  upper  second 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       721 

molar.  There  is  lack  of  contact  with  the  third  molar  tooth.  Note  the 
feather  edge  at  the  cervical  margin,  distal  side.  Roentgen  fihii  (Fig. 
639)  shows  a  disto-occlusal  gold  inlay  i,n  the  lower  first  molar,  fitting 
poorly  at  the  cervical  margin.  Note  also  the  poor  filling  at  the  distal 
side  of  the  second  bicuspid,  with  decay  underneath. 

Restoration  by  Crown  and  Bridge-work. 

A  careful,  systematic  study  of  crown  and  bridge-work  gives  evidence 
of  the  fact  that  very  little  attention  is  paid  to  the  condition  of  the  teeth 
or  roots,  which  are  used  as  abutments.  The  problem  is,  by  many, 
regarded  as  a  purely  mechanical  one,  simply  to  restore  the  masticating 
efficiency  and  the  appearance,  and  any  tooth  which  is  useful  as  a 
mechanical  support  is  retained  without  investigation  of  its  condition. 
This  short-sightedness  often  makes  it  necessary  to  destroy  bridges  of 
very  recent  construction  in  order  to  remove  an  abutment  which  is 
causing  extensive  periapical  infection  or  to  treat  the  root  canal  of  a 
tooth  in  which  the  pulp  has  become  infected. 

Roentgen  Diagnosis  before  Planning  Crown  and  Bridge-work. — 
Before  undertaking  any  restoration  the  teeth  which  are  to  be  used  as 
abutments  should  be  carefully  roentgenographed.  It  is  necessary  to 
determine  whether  a  tooth  is  vital  or  whether  its  pulp  is  infected.  If 
it  is  devitalized  the  quality  of  its  root-canal  filling  should  be  investi- 
gated and  possible  bone  infection  around  the  apex  of  the  tooth  should 
be  discovered.  If  there  be  a  chronic  alveolar  abscess  present  the  out- 
line of  the  root  may  be  found  to  be  either  normal  or  pathologically 
changed.  In  the  latter  case  there  may  be  absorption  or  hypercemen- 
tosis  of  the  apex.  Sometimes  unerupted  teeth  are  discovered  and 
quite  frequently  there  are  broken-off  roots,  over  which  the  gum  may 
have  completely  healed,  in  the  alveolar  process  which  is  to  be  covered 
by  a  bridge.  Fig.  640  shows  the  case  of  a  young  man  who  had  three 
porcelain  crowns  on  upper  incisors.  These  crowns  were  of  very  good 
appearance,  but  after  a  short  time,  when  his  general  health  became 
poor,  an  acute  process  set  in,  causing  acute  suppurating  ostitis  of  the 
jaw.  A  roentgen  picture,  taken  at  this  time,  showed  bone  infection 
around  the  roots,  and  the  apical  part  of  the  pulp  canals  was  entirely 
unfilled.  It  also  revealed  partial  root-canal  filling  in  a  bicuspid,  to 
which  was  attached  a  gold  crown  and  dummy.  This  tooth  also  shows 
slight  infection  around  the  apex  of  the  root.  Fig.  641  shows  a  case  in 
which  a  large  fixed  bridge  had  been  constructed  to  replace  several 
missing  teeth.  Sometime  after  the  bridge  had  been  cemented  into 
place  the  central  incisor  began  to  get  sore.  A  roentgen  picture 
revealed  an  unerupted  cuspid  pressing  against  the  root  of  the  incisor. 
46 


722       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

Fig.  642  shows  a  small  bridge  attached  to  a  vital  bicuspid.     When  the 
patient  was  seen  she  complained  of  soreness  in  the  gum,  and,  without 


Fig.  640 


Fig.  641 


a  roentgen  picture,  one  might  have  been  led  to  believe  that  the  pulj) 
in  the  bicuspid  had  become  infected.     The  picture,  however,  showed 


Fig.  642 


Fig.  643 


Fig.  644 


Fig.  645 


that  one  of  the  apices  of  the  first  bicuspid  had  been  left  in  the  jaw 
and  the  dark  area  around  it  showed  there  was  a  good-sized  abscess 


SPECIAL  ROmTGBN  STUDY  OF  DENTAL  DISEASES      723 

connected  with  this  root.  Fig.  643  is  a  picture  of  a  bridge  made  seven 
years  ago.  The  patient  had  no  symptoms.  Only  the  anterior  abut- 
ment is  shown  in  this  picture.  There  is  a  partial  root-canal  filling 
and  a  large  area  around  the  apex,  indicating  bone  involvement.  The 
floor  of  the  antrum  is  clearly  outlined.  Examination  of  the  antrum 
revealed  abnormal  condition.  There  are  also  pockets  at  each  side 
of  the  tooth.  Fig.  644  shows  a  bridge  in  the  mouth  of  a  patient  who 
had  been  suffering  from  arthritis  for  about  a  year.  He  had  several 
abscesses  on  other  teeth.  The  illustrated  bridge  is  attached  to  a 
bicuspid  with  corkscrew  root-canal  filhng  and  a  molar,  which  shows 
decay  at  the  mesial  side  under  the  crown.  A  root  has  been  left  under 
the  bridge  and  the  patient  complained  of  soreness  of  the  gum.  Clinical 
examination  showed  an  inflammatory  condition,  due  to  lack  of  hygiene 
and  probably  also  infection  from  the  root.  Fig.  645  shows  a  roentgen- 
ogram of  a  patient  who  complained  of  slight  pain  on  the  right  side  of 
the  face  and  discharge  from  the  nose.  A  roentgen  picture  of  the 
maxiUary  sinuses  verified  the  clinical  findings  of  a  diseased  antrum. 
Besides  an  infected  pulp  in  the  right  upper  first  molar,  due  to  decay, 
there  is  a  second  bicuspid  holding  a  small  bridge.  The  pulp  in  the 
bicuspid  must  have  become  infected,  as  evidenced  by  the  changes 
around  its  apex,  which  indicate  the  pathologic  condition  of  the  bone. 
In  addition  there  is  an  infected  root  underneath  the  dummy. 

The  Pulp  of  the  Bridge  Abutment. — Since  our  better  knowledge  of 
the  pathologic  conditions,  both  local  and  systemic,  so  frequently 
caused  by  devitalized  teeth,  we  have  been  impressed  with  the  serious- 
ness of  pulp  extirpation.  Whenever  possible  restoration  should  be 
made  without  sacrifice  of  the  pulps  in  normal  teeth.  If,  however, 
the  pulp  has  become  involved  from  decay,  or  if  there  is  danger  that 
pathologic  processes  may  start  after  the  bridge  is  made,  it  is,  of 
course,  better  to  consider  its  removal  under  favorable  conditions. 
A  careful  roentgen  study  should  be  made  to  determine  whether  root 
treatment  is  advisable.  The  various  steps  in  the  root-canal  treat- 
ment should  be  checked  up  by  means  of  other  pictures,  as  described 
later.  It  is  a  mistake  to  believe  that  a  tooth  must  be  devitalized  for 
the  attachment  of  a  gold  or  porcelain  jacket  crown.  The  author  has 
seen  many  roentgenograms  of  teeth  which  were  perfectly  normal  after 
carrying  crowns  for  a  long  time.  Fig.  646  shows  an  upper  bicuspid 
with  a  gold  crown  which  has  been  on  the  tooth  more  than  ten  years 
without  causing  any  pathologic  condition.  Fig.  647  shows  two  jacket 
crowns  on  a  cuspid  and  bicuspid  with  normal  pulps. 

If  pulp  disease  is  found  it  may  have  started  when  the  tooth  was 
prepared  or  chronic  infection  of  the  pulp  and  periapical  tissues  may 
have  existed  before  the  crown  was  made.     Again,  the   pulp    disease 


724       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

may  have  been  caused  by  decay  starting  under  poorly  fitting  crowns 
and  unclean  bridges  or  from  improper  root-canal  work.  Fig.  648  shows 
a  jacket  crown  on  a  tooth  with  signs  of  periapical  infection,  due  to 


\jXjg 


Fig.   646 


Fig.   647 


chronic  pulpitis.  Fig.  649  reveals  extensive  chronic  bone  infection 
around  the  root  of  a  lateral  incisor  to  which  a  porcelain  crown  had 
recently  been  attached.     The  apical  part  of  the  canal  is  not  filled, 


Fig.   648 


Fig.   649 


the  infection  probably  having  existed  before  treatment  was  under- 
taken by  the  dentist.  Fig.  650  shows  a  first  molar  with  a  gold  crown. 
At  its  mesial  side  a  cavity  had  formed,  which  almost  separated  the 


Fig.  650 


Fig.   651 


mesio-buccal  root.  Fig.  651  is  a  roentgenogram  of  a  patient  who  had 
a  slight  infection  at  the  apex  of  a  bicuspid,  the  root  canal  of  which 
had  not  been  properly  treated  before  the  bridge  was  attached.  Note 
also  the  large  area  around  the  cuspid. 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       T2'h 

Technical  Constraction. — Perfect  mechanical  results  are  quite  as 
important  as  proper  diagnosis.  Fixed  bridges  are,  of  course,  contra- 
indicated   in  patients  who   will   not  take  proper  care  of  their  teeth 


Fig.  652 


Fig.  653 


and  mouth,  and  unless  they  are  willing  to  have  regular  prophylactic 
treatments  and  to  do  their  part  at  home,  removable  bridge-work  only 
should  be  considered.     Fig,  652  shows  a  bridge  which  caused  infection 


Fig.  654 


Fig.  655 


of  the  abutments  and  loss  of  almost  all  the  alveolar  structure  on 
account  of  septic  conditions.  In  the  bridge  shown  in  Fig.  653  decay 
had  progressed  underneath  a  crown  to  such  an  extent  as  to  separate 


Fig.  656 


Fig.  657 


almost  entirely  the  roots  from  the  crown.  The  fit,  or  misfit,  at  the 
cervical  margin  can  be  shown  up  very  nicely  in  roentgen  pictures,  as 
seen  in  Fig.  654,  which  shows  that  a  large  surplus  of  cement  has  been 


726       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

left  at  the  mesial  side  in  the  interproximate  space.  Fig.  655  shows  a 
crown  with  a  large  overhang  at  the  mesial  side.  Fig.  656  shows  the 
very  poor  fit  of  a  gold  crown  at  the  cervix,  and  in  Fig.  657  an  extreme 
overhang  at  the  margin  of  the  mesial  side  is  shown. 


Fig.  658 


Fig.  659 


SPECIAL   ROENTGEN  STUDY  OF  DENTAL  DISEASES       727 

Good  work  can  also  be  proved  by  means  of  roentgen  pictures.  Figs. 
658  and  659  show  two  cases  in  point.  The  first  (Fig.  658)  shows 
a  bridge  mth  inlay  attachments  in  the  lower  jaw.  The  other  picture, 
Fig.  659,  illustrates  another  case.     Both  of  these  show  beautiful  fits. 

Pulp  Disease  and  Treatment  of  Root  Canals. 

The  greatest  benefit  the  dentist  has  derived  from  the  roentgen  ray 
is,  without  doubt,  its  use  in  diagnosing  conditions  of  pulps  and  root 
canals  and  to  check  up  the  progress  of  root-canal  cleaning  and  filling. 
This  work  has  heretofore  been  very  unsatisfactory,  not  only  on  account 
of  obscure  conditions  which  could  not  be  properly  diagnosed,  but,  for 
the  same  reason,  because  of  the  small  percentage  of  perfect  results 
obtained.  The  following  general  conclusions  of  the  result  of  root-canal 
operation,  performed  without  the  aid  of  the  roentgen  method  may 
be  drawn  from  examining  many  thousands  of  roentgenograms. 

1.  A  very  small  percentage  of  devitalized  teeth  show  perfect  root 
canal  fillings.  Of  these  some  show  entirely  normal  conditions  of 
the  periapical  tissue,  as  far  as  one  is  able  to  judge  from  a  perfect 
roentgen  picture,  while  others  reveal  decided  periapical  changes 
notwithstanding  the  fact  that  the  whole  canal,  as  far  as  the  apex,  may 
have  been  filled.  Whether  such  conditions  are  due  to  periapical 
infection  having  occurred  before  the  root  canal  operation  was  per- 
formed, and  having  persisted,  or  whether  they  represent  an  infection 
which  took  place  during  or  after  the  filling  of  the  canal,  cannot  be 
ascertained.  Fig.  660  is  a  roentgen  picture  of  a  tooth  with  a  perfect 
root-canal  filling,  done  twenty-one  years  ago.  The  periapical  tissue 
appears  normal.  Fig.  661  shows  a  tooth  with  a  perfect  root-canal 
filling  and  periapical  infection. 

2.  A  certain  number  of  roentgen  pictures  show  up  accidents  which 
happened  during  the  root-canal  operation.  The  most  frequent  ones 
are  caused  by  motor-driven  root-canal  instruments.  They  are  also 
due  to  miscalculation  of  the  direction  of  the  canal  or  to  crooked  roots. 
Fig.  662  illustrates  a  case  in  which  a  perforation  is  seen  in  the  lateral 
incisor.  The  channel,  which  is  very  large,  extends  to  the  distal  side 
and  must  have  been  made  by  a  burr  or  engine  reamer.  Fig.  663  shows 
another  case.  A  first  bicuspid,  with  a  porcelain  crown  attached  by 
means  of  a  post,  revealed  no  visible  root-canal  filling,  and  the  post 
is  seen  to  extend  just  through  the  distal  surface  of  the  root.  There  is 
a  radiolucent  area  both  at  the  apex  of  the  tooth  and  on  the  side, 
indicating  that  infection  has  occurred  in  both  places. 

3.  Poor  root-canal  fillings,  on  account  of  anatomic  conditions  or 
Calcifications  obstructing  the  canal,  are  not  so  frequently  found  as 


728       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

those  due  to  faulty   technic,  which  will  be  considered  later.     Fig. 
664  shows   an   anatomic   vagary  which  made    a  perfect  root-canal 


Fig.  660 


Fig. 


filling  impossible.    The  root  of  the  second  bicuspid  is  very  crooked, 
but  it  must  be  admitted  that  even  in  this  case  a  better  result  might 


Fig.  662 


Fig.   663 


have  been  expected.     In  Fig.  665  the  canal  in  the  lateral  is  obstructed 
by  calcareous  deposits  and  makes  root-canal  treatment  impossible. 


Fig.   664 


Fig.  665 


4.  By  far  the  largest  percentage  of  poor  root-canal  fillings  are 
caused  by  improper  and  careless  technic,  and  because  before  the  use 
of  the  roentgen  ray  there  was  no  means  of  telling  whether  the  operation 
was  successful  or  not.    No  doubt  in  most  cases  the  work  was  done 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES      729 

as  well  as  possible  under  the  circumstances,  but  toda}-  there  is  no 
excuse  for  working  in  the  dark.  A  small  percentage  of  partly  filled 
root  canals  show  no  periapical  infection.     Whether  this  is  due  to 


Fig.  666 


Fig.  667 


perfect  sterilization  and  aseptic  methods  or  to  antiseptic  preparations 
used  in  connection  with  the  filling  it  is  difficult  to  determine.  Fig. 
666  shows  a  lower  bicuspid  with  the  root  only  half -filled.     Although 


Fig.  668 


Fig.  669 


the  tooth  had  been  in  this  condition  for  many  years  the  peridental 
membrane  and  the  bone  around  the  apex  show  no  changes  whatever. 
However,  the  majority  of  teeth  with  poor  and  incomplete  root-canal 


Fig.  670 


Fig.  671 


fillings  show  involvement  of  the  periapical  tissue,  affecting  not  only 
the  peridental  membrane  but  also  the  tooth  tissue  and  the  bone. 
Teeth  bearing  porcelain  crowns  attached  by  means  of  posts  invariably 


730       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

have  poor  root-canal  fillings.  This  may  be  because  crown  and  bridge- 
workers  do  not  pay  enough  attention  to  the  proper  treatment  and 
filling  of  root  canals  or  because  frequently  the  root  filling  is  torn  out 
of  the  canal  when  using  reamers  to  fit  the  post.  Fig.  667  illustrates 
such  a  case.  Pictures  of  teeth  showing  partial  filling,  a  broken  instru- 
ment in  the  canal,  cork-screw  filling  and  poorly  condensed  fillings 
are  presented  in  Figs.  668,  669,  670  and  671. 


i      k 


Fig.  672 


Fig.  673 


Roentgen  Diagnosis  of  Pathologic  Changes  of  the  Pulp.  — 
Secondary  Dentin,  Pulp  Nodules  and  Calcifications. — These  are  the 
only  changes  of  the  pulp  which  can  actually  be  demonstrated  in  a 
roentgenogram.  In  the  case  of  secondary  dentin  the  outline  of  the 
root  canal  is  changed,  while  pulp  nodules  and  calcifications  cause  a 
direct  change  in  the  radiability  of  the  pulp.  The  nodules  may  be 
round  or  oblong  and  calcifications  may  close  up  and  obstruct  the 
entire  lumen  of  the  root  canal.     Fig.  672  is  a  picture  of  the  left  lower 


Fig.  674 


Fig.  675 


molars  of  a  patient  who  had  worn  down  the  occlusal  surfaces  of  his 
teeth.  Secondary  dentin  had  formed,  decreasing  the  size  of  the  pulp 
chamber.  Compare  the  size  of  the  pulp  chambers  in  the  first  and 
second  molars.  Fig.  673  shows  large  calcareous  deposits  in  the  pulp 
chamber  of  the  first  molar.  Fig.  674  shows  formation  of  calculi  in 
the  canals  of  both  central  incisors.  Note  also  the  accessory  foramen 
in  the  left  central  incisor,    Fig.  675  reveals  9,  round  pulp  nodule  in  the 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DLSEASES      731 

pulps  of  two  upper  molars.  The  patient  had  attacks  of  neuralgia  at 
intervals  on  this  side  of  the  face,  which  had  become  more  severe, 
including  also  the  ear,  three  days  before  he  was  examined.  Removal 
of  the  pulps  in  both  the  second  and  third  molars  permanently  relieved 
all  symptoms.  In  Figs.  676  and  677  calcareous  deposits  in  the  pulp 
canals  of  teeth  are  shown. 


Fig.  676 


Fig.  677 


Pulp  Infection  and  Necrosis. — Inflammatory  and  infectious  changes 
cannot  be  directly  demonstrated  by  means  of  the  roentgen  ray,  but 
by  comparing  clinical  symptoms  and  roentgen  findings  it  is  sometimes 
possible  to  make  important  discoveries.  Fig.  678  is  a  roentgenogram 
of  the  anterior  teeth  in  the  lower  jaw.  The  patient  had  been  suffering 
a  great  deal  of  pain  for  two  nights.  A  cavity  is  seen  in  the  lateral 
incisor  near  the  cervical  margin,  extending  close  to  the  pulp.  The 
pain,  therefore,  is  due  to  a  pulpitis  in  this  tooth  and  was  caused  by 


Fig.  678 


Fig.  679 


infection  from  the  decay.  Another  patient  had  been  suffering  from 
neuralgic  pain  on  the  right  side.  Clinical  examination  revealed 
nothing  important,  but  there  was  a  history  of  the  pulp  in  the  first 
molar  having  been  capped.  Fig.  679  shows  that  the  filling  extends 
close  to  the  pulp.  Slight  changes  are  noticeable  around  the  apices 
of  both  roots,  but  these  have  not  the  appearance  of  typical  periapical 
infection.  From  these  findings  a  diagnosis  of  necrosis  of  the  pulp 
in  the  first  molar  may  be  made.  The  operative  findings  confirmed 
the  diagnosis, 


732       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

Frequently  it  is  possible  to  draw  the  necessary  deductions  from 
the  roentgenogram  alone  in  order  to  make  a  diagnosis  of  pulp  disease. 
This  is  especially  important  in  all  cases  of  chronic  pulpitis  without 
history  or  symptoms.  As  soon  as  the  infection  spreads  from  the 
pulp  through  the  apical  foramen,  changes  can  be  demonstrated  in 
the  periapical  tissue.  If  these  findings  are  seen  connected  with  a 
tooth  in  which  the  root  canal  has  never  been  treated,  and  if,  in  addi- 


FiG.  680 


Fig.  681 


tion,  we  can  demonstrate  some  causative  factor,  the  diagnosis  of  pulp 
disease  may  be  made  with  certainty.  Fig.  680  shows  periapical  changes 
around  the  roots  of  the  upper  first  molar.  There  is  also  decay  at 
the  cervical  margin  under  the  filling.  The  diagnosis,  therefore,  is 
chronic  pulpitis  and  periapical  infection.  Fig.  681  is  an  interesting 
study.  Periapical  infection,  apparently  caused  by  pulp  disease,  is 
revealed  on  all  four  lower  incisors.  Many  porcelain  cement  fillings 
and  two  gold  fillings  appear  in  the  crowns.     Whether  the  infection 


Fig.  682 


Fig.  683 


originated  because  the  patient  neglected  to  have  the  cavities  excavated 
and  filled  when  they  were  small  or  whether  it  was  due  to  some  action 
of  the  porcelain  cement  is  not  so  easily  determined.  Attention  has 
already  been  drawn  to  pulp  disease  caused  by.  crowns  and  bridges. 
This  is  usually  due  to  an  infection  having  occurred  before  the  crown  is 
cemented  on  the  tooth  (Fig.  682),  or  to  decay  which  starts  under  the 
gum  or  under  a  poorly  fitting  crown  after  the  cement  has  washed  out. 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       733 

Fig.  083  sliows  such  a  coiulition  in  which  l)ull>  infection  has  been  caused 
by  decay  at  the  distal  side  luider  the  crown  of  the  first  bicuspid;  there 
is  also  decay  under  the  inlay  in  the  second  bicuspid. 

In  the  cases  mentioned  so  far  the  infection  of  the  i)uli)  started  from 
the  crown  of  the  tooth  and  extended  through  the  canal  into  the  peri- 
apical tissues.  In  some  cases  the  infection  travels  along  the  peri- 
dental membrane,  forming  a  pus  pocket  at  the  side  of  a  tooth.  On 
reaching  the  apex  pulp  infection  occurs  as  illustrated  in  Fig.  684. 


Fig.  684 


Fig.  685 


The  patient  had  some  pain  in  the  left  side  of  the  low^er  jaw,  and  after 
a  roentgenogram  was  taken  the  left  lower  first  molar  was  extracted. 
The  symptoms  continued  oflF  and  on  and  did  not  entirely  disappear, 
A  few  days  before  the  author  saw  the  patient  the  pain  had  grown 
worse  and  the  second  molar  had  become  loose  and  sore.  A  roentgen 
picture  taken  at  this  time  is  shown  in  Fig.  684.  Apparently  the  pocket 
had  existed  between  the  first  and  second, molar  and  is  still  visible  in 


Fig.  686 


Fig.  687 


the  negative.     The  infection  had  spread  from  this  pocket  to  the  apex 
of  the  second  molar,  causing  infection  of  the  pulp. 

Another  possibility  of  pulp  infection  is  presented  by  the  case  shown 
in  Fig.  685.  It  discloses  periapical  infection  on  the  lateral  mcisor 
w^hich  had  been  treated.  The  tooth  next  to  it,  although  perfectly 
sound,  with  no  cavity  or  filling,  had  an  infected  pulp,  which  reacted 
to  the  heat  test.  It  had  become  infected  from  the  periapical  infection, 
which  had  spread  from  the  neighboring  tooth. 


734     ROENTGEN  Diagnosis  in  operative  dentistry 


Prognostic  Roentgen  Examination  before  Treating  Pulps  or  Root 
Canals. — Before  undertaking  any  pulp  canal  operation,  no  matter 
whether  the  pulp  be  normal  or  diseased,  it  is  absolutely  necessary  to 


B«' 


Fig.  688 


Fig. 


make  a  careful  diagnosis  of  the  condition  of  the  root  and  root  canal 
by  means  of  the  roentgen  ray.     The  root  may  show  abnormal  devel- 


FiG.  690 


Fig.  691 


opment  or  deviations  in  the  number,  size  and  location  of  the  root 
canals.     Fig.  686  shows  two  bent  bicuspid  roots  and  Fig.  687  a  very 


Fig.  692 


Fig.  693 


badly  curved  root  of  an  upper  first  bicuspid.    Root-canal  treatment 
would  be  contra-indicated  in  a  case  like  this. 


Special  roentgen  study  of  dental  diseases    735 

The  apical  part  of  the  tooth  presents  many  variations  besides  decided 
curves  at  the  very  end.  We  frequently  find  one  or  more  accessory 
foramina,  and  the  number  of  root  canals  is  not  as  staple  as  one  might 
be  led  to  believe  from  the  older  text-books  on  dental  anatomy.  Two 
canals  are  frequently  found  in  the  lower  bicuspids;  even  three  occa- 
sionally, while  the  mandibular  cuspids  and  incisors  quite  often  have 
bifurcated  canals  leading  to  a  common  foramen.  The  lower  molars 
sometimes  present  in  each  root  two  canals  and  the  third  molars  are, 
of  course,  always  uncertain.  In  young  teeth  the  apical  foramen  is  very 
large  and  funnel  shaped  (Fig.  688),  while  we  sometimes  find  lack  of 
proper  development  in  vital  teeth,  as  seen  in  Fig.  689.  The  patient, 
who  had  had  orthodontic  treatment,  had  a  roentgen  picture  taken  to 
locate  the  permanent  cuspid,  which  was  missing.  The  roentgenogram 
showed  also  a  very  peculiar  condition  at  the  apices  of  all  four  incisors, 
from  which  one  might  be  led  to  believe  that  absorption  had  taken 
place.  Fig.  690  shows  a  bifurcated  root  canal  in  a  lower  first  bicuspid 
and  in  Fig.  691  an  accessory  canal  is  shown  in  an  upper  central  incisor. 
Two  canals  are  seen  in  both  lower  bicuspids  in  Fig.  692  and  Fig.  693. 
Pathologic  changes  outside  the  tooth,  but  closely  connected  with 
the  root  canal,  should  also  be  properly  diagnosed  before  deciding  on 
the  method  of  treatment.  The  author  has  seen  cases  in  which  root 
canals  have  been  treated  for  months  without  ever  getting  a  sterile 
condition.  Roentgenograms  of  these  cases  revealed  conditions  which 
never  could  have  been  affected  by  root-canal  medication  nor  by 
thermal  or  electrolytic  treatment.  Necrosis  of  the  cementum  at  the 
apical  part  of  the  root  and  extensive  bone  infection,  as  well  as  enor- 
mous cysts,  are  often  revealed  by  roentgen  examination.  Such  cases 
are  cited  under  the  headings  in  which  their  pathology  and  diagnosis 
are  discussed. 

The  Roentgen  Ray  as  an  Aid  in  Root  Canal  Cleaning.— The 
importance  of  the  removal  of  every  particle  of  pulp  tissue,  whether 
normal  or  diseased,  from  the  canal  or  canals  of  a  tooth  has  only 
recently  b*een  fully  realized.  It  is  also  important  to  properly  and 
completely  ream  the  root  canal  and  to  enlarge  it  slightly  either 
by  mechanical  or  chemical  means,  so  as  to  facilitate  the  filling  of 
the  canal.  The  only  safe  and  sure  way  to  determine  whether  the 
canal  is  properly  prepared  for  successful  filling  is  by  taking  roentgen- 
ograms. If  the  operator  has  a  roentgen  machine  by  his  chair  he  can 
insert  broaches  and  take  pictures  with  the  rubber  dam  on,  developing 
the  films  at  once  and  so  losing  no  time.  When  taking  pictures  the 
rubber  dam  clamp  should  be  removed  and  replaced  with  heavy  liga- 
tures, to  avoid  confusion  in  the  picture.  If  the  film  is  to  be  taken  at 
some  future  time,  or  if  the  patient  is  to  be  referred  to  a  roentgenologist. 


736       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

fine  wires  witli  looped  ends  can  be  inserted  into  the  canals,  together 
with  a  root-canal  dressing,  after  which  the  cavity  is  sealed  as  usual. 
The  process  should  be  repeated  until  a  picture  shows  the  wire  inserted 
to  the  very  end  of  the  root. 


Fig.  694 


Fig.  695 


The  Roentgen  Ray  as  an  Aid  in  Root  Canal  Filling. — ^The 
filling  of  root  canals  should  also  be  checked  up  by  means  of 
roentgen  pictures.     Gutta-percha   or   chloropercha,   or   the   solution 


Fig.  696 


which  forms  when  the  root-canal  point  dissolves  in  the  chloroform 
and  rosin  when  Callahan's  method  is  used,  are  of  radiopaque  nature 


Fig.  697 


Fig.  698 


and  show  clearly  in  the  roentgenogram.  This  investigation  should 
be  made  immediately  after  the  filling  is  placed  in  the  canal,  because 
at  that  time  it  is  easy  to  condense  it  further,  press  it  deeper  into  the 


SPECIAL  ROENTCEN  STUDY  OF  DENTAL  DISEASES 


M 


canal  or  remove  it,  so  that  it  can  be  replaced  by  a  more  perfect  one. 
Figs.  694  to  698  show  pictures  taken  for  the  cleaning  and  filling  of  the 
canals  of  a  lower  molar.  In  Fig.  699  a  root-canal  filling  with  a  so-called 
"cap'ping"  at  the  apex  is  shown.  The  canal  in  Fig.  700  is  filled  just 
to  the  apex,  and  in  Fig.  701  the  canal  filling  of  a  central  incisor  is  shown 
to  include  both  the  main  and  accessory  foramina. 


Fig.  699 


Fig.  700 


Fig.  701 


Checking  up   Devitalized    Teeth    by   the    Roentgen    Method.^ 

It  is  highly  commendable  to  take  roentgenograms  of  devitalized 
teeth  at  certain  intervals  to  find  out  whether  they  remain  normal 
or  become  absorbed  and  cause  bone  infection.  If  a  slight  periapical 
infection  existed  when  the  root  canal  was  treated  the  tooth  should 
again  be  examined  after  six  months,  and  after  one  year  to  ascertain 
whether  the  bone  changes  have  been  repaired.  If  this  is  found  to  be 
the  case  it  indicates  that  the  tooth  is  sterile  and  is  being  tolerated 
by  the  system. 

Periapical  Infection. 

Before  discussing  the  roentgen  method  of  diagnosing  periapical 
infection  it  is  first  necessary  to  review  briefly  the  pathology  of  such 
conditions.  The  infection  caused  by  pulp  disease  starts,  as  a  rule, 
at  a  natural  opening  of  the  root  canal,  the  apical  foramen.  We, 
however,  occasionally  find  infection  at  the  side  of  a  root,  generally  on 
account  of  accidental  perforation  of  the  root  by  an  engine  reamer  or 
other  root-canal  instruments.  If  such  injury  is  followed  by  infection 
an  abscess  may  form  at  this  point,  and  we  speak  of  it  as  a  lateral 
abscess.  Fig.  702  shows  such  a  root  with  a  lateral  abscess.  If  a  per- 
foration is  made  between  the  roots  of  a  multi-rooted  tooth  and  infection 
occurs  it  is  spoken  of  as  an  inter-radicular  abscess.  Such  a  case  is 
shown  in  Fig.  703  in  which  the  floor  of  the  pulp  chamber  has  been 
perforated. 
47 


738       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

Periapical  infection  originating  from  a  diseased  dental  pulp  may 
follow  either  of  two  chains  of  pathologic  changes.  The  first  is  of 
a  destructive  nature  and  begins  with  a  reaction  causing  all  the  symp- 
toms of  acute  inflammation,  while  the  other,  from  the  beginning,  is 
characterized  by  a  mild  and  chronic  reaction,  which  starts  and  con- 
tinues without  giving  any  local  symptoms. 


Fig.  702 


Fig.  703 


Acute  Periapical  Infection. — This  condition  starts  as  acute  perio- 
dontitis and  involves  a  violent  inflammatory  reaction  of  the  tissue. 
Serum  and  polymorphonuclear  leukocytes  infiltrate  the  tissue,  causing 
an  increase  in  volume  of  the  peridental  membrane,  which  results  in 
the  well-known  symptom  which  gives  the  impression  that  the  tooth 
has  become  elongated.  Purulent  exudations  soon  accumulate,  the 
cells  of  the  periodontal  membrane  and  the  surrounding  bone  being 
destroyed,  and  the  condition  is  then  called  an  acute  alveolar  abscess. 
This  may  spread  and  cause  suppurating  ostitis  of  greater  extent  or 
else  the  pus  may  soon  find  an  outlet  to  the  surface  via  the  Haversian 
canals,  which  penetrate  the  outer  cortical  layer  of  the  bone.  When 
the  pus  collects  under  the  periosteum  a  reaction  sets  in  at  once,  caus- 
ing a  widespread  serous  infiltration  of  the  soft  parts,  cheek  or  neck. 
Finally  the  pus  burrows  a  channel  through  the  soft  tissue,  forming  a 
fistula  into  the  mouth,  nose,  maxillary  sinus  or  outside  of  the  face. 
After  this  process  of  destruction  has  reached  its  climax  nature  makes 
an  attempt  at  repair  and  the  acute  symptoms  disappear;  but  unless 
the  cause  (a  diseased  pulp  or  necrosed  root  apex)  is  removed  the 
condition  becomes  chronic.  In  this  stage  it  may  last  for  an  indefinite 
period,  with  the  fistula  discharging  pus  if  the  destructive  process 
becomes  more  active,  or  closing  up  for  a  time  if  the  defensive  system 
predominates,  only  to  reopen  with  more  or  less  marked  subacute 
symptoms  when  suppuration  again  becomes  more  active. 

The  roentgen  picture  shows  at  first  an  increased  space  between  the 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       739 

alveolar  socket  and  the  apex  of  the  tooth.  This  is  a  sign  of  perio- 
dontitis. Pus,  which  accumulates  in  the  cancellous  part  of  the  bone, 
may  cause  a  tremendous  reaction  in  the  tissues  before  enough  bone 
destruction  has  taken  place  to  become  visible  in  the  roentgen  picture. 
At  other  times,  especially  if  the  apex  of  the  tooth  is  near  the  surface, 
the  pus  may  gather  under  the  soft  tissues  without  affecting  the  bone 
to  any  great  extent,  and  so  give  no  roentgenographic  record.  A  case 
which  exemplifies  this  is  that  of  a  patient  who  had  suffered  from  a 
swelling  under  the  lip  for  several  days.  Clinical  examination  showed 
a  protruding  upper  lip  and  large  swelling  on  the  gum.  The  anterior 
teeth  in  the  upper  jaw  had  large  fillings,  gold  in  the  lateral  and  porce- 
lain in  the  central  incisor.  Both  were  loose  and  tender  to  the  touch. 
Fig.  704  shows  no  radiolucent  area,  as  might  perhaps  be  expected  with 
such  large  abscess  formation.  The  lateral  incisor  was  opened  and  the 
pulp  found  to  be  very  putrescent.  An  incision  on  the  labial  part  of  the 
gum  released  about  an  ounce  of  pus. 


Fig.  704  Fig.  705  Fig.  706 

Sometimes,  however,  the  bone  becomes  extensively  involved  before 
an  outlet  is  made.  In  such  cases  a  large  radiolucent  area  is  usually 
found  around  the  apex  of  the  tooth.  A  case  of  acute  alveolar  abscess 
of  this  nature  is  seen  in  Fig.  705.  The  central  incisor  had  recently 
been  filled  on  the  labial  side.  The  tooth  then  started  to  ache  and  the 
condition  became  worse.  When  examined  the  left  central  incisor  was 
very  loose  and  tender  and  the  two  neighboring  teeth  were  also  slightly 
affected.  The  gum  was  swollen  and  the  lip  protruded.  Roentgen 
examination  showed  a  large  radiolucent  area,  apparently  starting  from 
the  left  central  incisor.  The  infection  must  have  spread  from  the  pulp 
to  the  bone,  causing  extensive  suppurative  ostitis. 

When  the  acute  stage  is  over  the  bone  destruction,  of  course,  is 
still  recognizable  in  the  roentgen  picture,  although  the  outer  swelling 


740       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

may  have  disappeared  entirely.  Slight  pus  formation  continues  in  the 
chronic  stage,  the  exudation  either  being  absorbed  or  discharged 
through  a  fistula  when  there  is  sufficient  accumulation.  Fig.  706 
shows  a  case  of  chronic  alveolar  abscess  which  had  become  more 
active.  The  pulp  was  infected,  and  when  the  roentgenogram  was 
taken  the  patient  was  having  a  subacute  attack.  The  amoimt  of 
bone  dissolved  is  clearly  indicated  by  the  radiolucent  area. 

Blind  Abscess  or  Dental  Granuloma. — The  difference  between  an 
acute  alveolar  abscess  and  a  blind  abscess,  or  dental  granuloma 
should  be  clearly  understood.  The  former  is  a  suppurative  inflam- 
mation and  involves  a  process  of  destruction  of  the  peridental  tis- 
sues, dissolving  them  into  pus.  The  latter  is  a  reaction  to  a  mild 
injurious  agent,  stimulating  inflammatory  new  growth  as  we  see  in 
specific  infections,  as  the  tuberculous  granuloma  (tubercle)  and  the 
syphilitic  granuloma  (gumma,  syphiloma).     Active  suppuration  does 


Fig.  707 

not  occur  at  first,  but  an  exacerbation  may  change  the  pathologic 
picture  so  as  to  simulate  a  typical  acute  alveolar  abscess.  The  blind 
abscess,  or  granuloma,  begins  and  continues  to  grow  without  giving 
any  symptoms.  The  defensive  system  of  the  body  takes  care  of  the 
slight  amount  of  pus  formed,  which  is  absorbed  through  the  lymphatics 
or  blood  channels.  When  speaking  of  a  blind  abscess,  therefore,  we 
must  think  of  a  focal  accumulation  of  leukocytes  and  lymphocytes 
in  the  newly  formed  granulation  tissue  rather  than  of  a  cavity  filled 
with  pus.  Sometimes  a  dental  granuloma  is  described  as  being  a 
tumor,  but  this  is  not  correct,  as  it  is  distinctly  of  infectious  origin  and 
histologically  presents  a  picture  of  chronic  inflammation. 

The  disease,  of  course,  spreads  at  the  expense  of  the  bone.  After 
the  stratum  durum  of  the  alveolar  socket  has  disappeared  the  infec- 
tion spreads  into  the  medullary  spaces,  destroying  the  trabeculi3e 
of  the  cancellous  part  of  the  bone.     The  process,  however,  is  not 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       741 


always  restricted  to  the  inner  part  of  the  bone.  When  the  tooth 
apex  is  near  the  surface,  or  if  the  lesion  is  extensive,  the  outer  cortical 
layer  frequently  becomes  involved.     The  Haversian  canals  are  next 


Fig.  708 


Fig.  709 


implicated  and  enlarged,  a  condition  which  Is  easily  recognizable  in 
a  skull,  by  the  many  small  holes  on  the  surface  of  the  bone  (osteo- 
porosis) (Fig.  707).    The  outer  plate  may  be  attacked  so  extensively 


Fig.   710 


Fig.  711 


that  a  part  of  it  disappears  entirely,  as  seen  in  Fig.  708.  It  is  evident 
that  if  a  hole  has  formed  in  the  outer  wall  of  the  bone  the  picture 
of  the  abscess  cavity  will  be  much  more  intense  (Fig.  709).     Similar 


Fig.  712 


bone  infection  is  shown  around  two  old  decayed  roots  of  a  lower  molar 
in  Fig.  710,  as  illustrated  by  a  similar  case  in  the  upper  jaw  shown  in 
If  the  disease  spreads  it  may  result  in  a  regular  granulating 


Fig.  711 


742       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

ostitis,  as  showr  in  Fig.  712,  where  the  infection  caused  extensive  bone 

destruction  without  giving  symptoms  or  causing  excessive  suppuration. 

The  first  reaction  which  occurs  in  the   peridental   membrane  is 


Fig.  713 


Fig.  714 


called  proliferating  periodontitis,  which  appears  in  the  roentgen 
picture  as  a  dark  shadow  of  very  moderate  size.  Fig.  713  shows  a 
devitalized  cuspid,  with  partial  root-canal  filling  and  a  slight  radiolu- 


FiG.  715 


Fig.  716 


cent  area  at  the  very  apex  of  the  tooth.  A  proliferating  periodontitis, 
but  a  slightly  more  extensive  one,  is  seen  in  Fig.  714,  where  a  cuspid 
with  partial  root-canal  filling  is  involved.     The    dark  area  around 


Fig.  717 


Fig.  718 


the  apex  is  slightly  larger.  Figs.  715  and  716  show  blind  abscesses,  or 
granulomata,  of  usual  size,  both  on  lateral  incisors.  There  is  a  fine 
difference  in  the  two  pictures.    Fig.  715  shows  a  blind  abscess  of  the 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       743 

granulating  ostitis  type,  while  Fig.  716  shows  a  granuloma  which  would 
develop  into  a  periodontal  cyst.  The  difference  in  the  roentgeno- 
graphic  aspect  of  these  conditions  lies  in  the  light  outline  of  the  dark 
area  in  Fig.  716,  which  is  typical  of  cyst  pictures  (see  paragraph  on 
Periodontal  Cysts) .  It  is  a  common  occurrence  to  find  blind  abscesses 
of  larger  size,  such  as  that  seen  in  Fig.  717  on  two  teeth.  Note  the 
gradual  change  from  diseased  to  normal  tissue.  This  is  typical  and 
indicates  the  spreading  character  of  the  disease.  Fig.  718  shows  a 
larger  area  still,  which  is  usually  spoken  of  as  granulating  ostitis. 
More  extensive  cases  are  described  under  a  special  heading  on  bone 
disease. 

It  should  be  noted  that  the  roentgenogram  does  not  show  whether 
the  periapical  infection  is  of  acute  or  chronic  character.  It  shows 
loss  of  bone  and,  on  account  of  the  space  where  the  bone  has  been 
destroyed  being  radiolucent,  a  dark  area  appears  in  the  picture. 
The  density  of  this  area  in  the  film  depends  upon  various  factors.  If 
the  abscess  cavity  is  shallow  and  on  the  surface,  or  inside  the  jaw 
only,  with  massive  cortical  layers  of  bone  on  each  side,  as  in  the  man- 
dible, the  radiability  is  but  little  affected.  When,  however,  the 
cavity  is  large  in  proportion  to  the  thickness  of  the  bone,  or  with 
a  large  opening  through  the  outer  or  inner  wall  of  the  bone,  the  radi- 
ability greatly  increases,  resulting  in  a  well-defined  dark  picture. 
The  contents  of  the  abscess  cavity  affects  the  radiability  very  slightly; 
whether  it  is  filled  with  liquid  pus  or  inflammatory  granulation  tissue 
makes  little  difference.  A  large  amount  of  cholesterin,  however,  may 
decrease  the  radiability,  as  the  author  had  occasion  to  observe  once 
or  twice,  when  the  abscess  almost  looked  as  if  it  had  healed. 

The  fact  that  blind  abscesses  develop  and  exist  without  causing 
pain  or  giving  other  local  symptoms  of  inflammation  makes  their 
discovery  impossible  without  the  use  of  the  roentgen  ray.  Teeth  with 
necrotic  roots  and  extensive  involvement  of  the  surrounding  bone 
often  remain  in  the  jaw  of  the  unsuspecting  individual,  unrecognized  by 
the  dentist  unless  he  makes  careful  roentgen  examination  of  all  the 
teeth. 

The  importance  of  recognizing  such  conditions  is  clearly  proved 
if  cultures  are  made  from  the  pus-soaked  tooth  after  its  extraction, 
although  its  odor  should  be  sufficient  proof.  It  is  today  almost  an 
offence  of  negligence  to  give  an  opinion  as  to  the  condition  of  a  patient's 
mouth  without  first  making  a  careful  roentgen  diagnosis. 

Complications  Caused  by  Periapical  Infection. — When  considering 
the  frequent  occurrence  of  these  localized  bone  abscesses  around  the 
teeth  it  is  surprising  that  one  does  not  encounter  more  often  a  spreading 
of  the  infection  to  adjoining  teeth,  extensive  involvement  of  the  jaws 


744        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

and  adjoining  cavities  of  the  face.  The  reason  for  the  infection  re- 
maining locahzed  on  one  tooth  is  not  easily  explained,  but  one  seldom 
gets  involvement  of  the  teeth  on  each  side  if  they  are  perfectly  normal. 
In  Fig.  719,  however,  we  see  a  devitalized  lateral  incisor  with  partial 
root-canal  filling  and  periapical  infection.  The  picture  of  the  abscess 
cavity  shows  that  it  is  connected  also  with  the  root  of  the  central 
incisor,  the  root  canal  of  which  has  never  been  opened.  The  patient, 
after  being  told  of  the  condition,  did  not  believe  that  it  was  of  any 
consequence,  as  it  had  never  given  her  any  trouble.  Nothing  was 
done  to  either  of  the  teeth.  She  came  to  the  office  two  days  later 
with  well-marked  symptoms  of  pulpitis  in  the  central  incisor.  A 
similar  case  is  shown  in  Fig.  720.  The  diseased  pulp  in  the  left  central 
with  a  porcelain  filling  apparently  attached  with  two  platinum  posts 
caused  infection  of  the  right  central,  which  was  otherwise  entirely 
normal.     Infection  and  pus  discharge  sometimes  persists  after  extrac- 


// 


Fig.  719  Fig.  720 

tion  of  a  tooth.  This  may  be  due  to  the  fact  that  two  teeth  were 
involved.  If,  for  example,  treatment  had  been  undertaken  in  the 
case  shown  in  Fig.  719  without  having  a  roentgen  diagnosis  made,  prob- 
ably only  one  tooth  would  have  been  extracted,  the  other  giving  no 
clinical  symptoms.  The  abscess  on  the  second  tooth  would,  of  course, 
have  continued  as  long  as  the  tooth  was  retained.  Such  a  case  is 
presented  by  a  patient  who  had  a  lower  second  bicuspid  extracted. 
Pus,  however,  continued  to  discharge  through  the  alveolar  socket 
where  the  tooth  had  been  removed.  The  roentgen  picture  is  shown  in 
Fig.  721  and  clearly  discloses  an  abscess  around  the  apex  of  the  first 
bicuspid,  with  a  definite  channel  to  the  place  where  the  other  tooth 
had  come  out. 

Bone  infection  is,  however,  not  always  eliminated  by  simply  extract- 
ing the  tooth.  This  is  shown  in  the  next  case.  The  patient  said 
that  the  upper  lateral  incisor  had  been  opened  and  the  pulp  removed 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       745 


two  years  previous  to  examination.  The  root  was  perforated  and 
finally  extracted  a  year  and  eight  months  later.  When  seen  by  the 
author  a  boil  had  formed  near  the  wing  of  the  nose.  The  roentgenogram 
in  Fig.  722  shows  the  condition.  A  bridge  had  been  attached  to  the 
cuspid  to  replace  the  lateral  incisor  and  in  the  bone  is  seen  a  dark  area, 
which  indicates  the  site  of  the  original  abscess  cavity.  When  opening 
it  from  the  labial  side  of  the  gum  it  was  found  to  be  filled  with  inflam- 
matory granulation  tissue,  containing  a  slight  amount  of  pus. 

In  another  case  the  nasal  cavity  was  involved.  The  patient  had 
a  swelling  of  the  face  and  complained  that  for  two  days  pus  had 
discharged  from  her  nose.  The  upper  central  incisor  was  very  sore 
and  a  roentgen  examination  was  resorted  to  for  diagnosis  of  the 
condition.  Fig.  723  shows  the  picture  in  which  a  dark  area  is  seen 
over  the  central  incisor.  The  tooth  had  a  necrotic  pulp,  and  after 
extracting  it  a  probe  could  be  passed  into  the  nose  through  a  fistula. 


n 


Fig.  721 


Fig.  722 


Fig.  723 


Infection  of  the  maxillary  sinuses  has  already  been  dealt  with  at 
length  under  a  separate  heading.  The  importance  of  careful  investi- 
gation of  the  teeth  in  sinus  disease  cannot  be  impressed  too  strongly. 

Other  more  serious  complications  are  seen  by  the  oral  surgeon  in 
increasing  numbers  and  quite  frequently  are  entirely  overlooked  by 
the  dentist,  or  are  improperly  diagnosed.  Among  these  belong  the 
various  bone  infections  and  periodontal  cysts,  which  are  also  of  infec- 
tious origin.     Such  diseases  will  be  considered  under  a  special  heading. 

Condition  of  the  Tooth  Apex. — Periapical  infection,  especially  if  it  is 
of  long  standing,  causes  changes  in  the  cementum  of  the  tooth.  Nutri- 
tion is  usually  disturbed,  the  cells  of  the  apical  part  of  the  periodental 
membrane  may  become  destroyed  and  the  cementum,  which  is  very 
porous  and  easily  absorbes  the  products  of  inflammation,  becomes 
pus-soaked.  In  this  condition  the  tooth  becomes  an  obnoxious 
foreign  body,  which  nature  tries  to  eliminate.     Osteoclastic  absorp- 


746       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

tion  starts  on  the  surface  of  the  cement,  which  then  presents  a  rough- 
ened appearance.  Marked  indentations  are  formed  and  the  cement, 
and  later  also  the  dentin,  dissolves.  The  recognition  of  this  condition 
in  a  roentgen  picture  is  of  greatest  importance,  because  it  indicates 
that  only  one  kind  of  treatment  is  possible,  either  root  resection  or 
extraction.  The  apex,  in  such  a  state,  is  a  dead  piece  of  bone,  and, 
like  a  sequestrum,  has  to  be  removed  before  healing  can  take  place. 


Fig.  724 


Fig.  725 


There  is  no  medicinal  treatment  which  could  restore  such  a  tooth  to 
its  normal  condition.  If  the  periapical  infection  is  of  recent  origin 
the  outline  of  the  root  is  usually  well  defined  and  clear  in  a  roentgen- 
ogram, which  shows  that  the  cementum  has  not  been  attacked  as 
yet.  Fig.  715  illustrates  such  a  case.  When  the  cement  becomes 
affected  first  an  indistinct  outline  of  the  apex  of  the  root  only  may 
be  observable.  Later  we  can  see  resorption  of  the  root,  due  to  osteo- 
clasia.    Fig.  724  shows  a  lateral  incisor  and  a  cuspid  with  periapical 


Fig.  726 


Fig.  727 


infection.  In  both  teeth  resorption  is  clearly  indicated  at  the  root 
apex.  In  Fig.  725  a  central  incisor  with  partial  root-canal  filling  is 
seen  showing  a  peculiar  dark  area,  indicating  resorption  at  the  side 
of  the  apex.  Two  upper  bicuspids  with  decided  loss  of  tissue  at  the 
apices  are  shown  in  Fig.  726.  A  similar  case,  in  which  the  disease 
has  become  more  extensive,  is  illustrated  in  the  roentgenogram  of  a 
cuspid  (Fig.  727).     Careful  study  is  necessary  to  detect  resorption  on 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       747 

the  mesial  root  of  the  first  molar  in  Fig.  728.     The  distal  root  shows 
only  a  roughness,  which  may  be  hardly  noticeable  in  the  printed 
reproduction  of  the  negative,  on  account  of  loss  of  detail,  while  a 
perfectly  normal  outline  of  the  cement  is  seen  on  the  roots  of  the 
twelve-year  molar. 


Fig.  728  Fig.  729 

Hypercementosis  in  various  stages  may  be  found  in  connection 
with  some  of  these  infections,  due  to  the  stimulation  of  some  cemento- 
blasts,  which  have  survived.  Fig.  729  shows  such  a  condition  on  the 
mesial  root.  Loss  of  tissue  can  be  noticed  at  the  very  apex,  but  on 
both  sides  of  the  root  end  a  decided  enlargement  has  taken  place. 
It  is  not  necessary  to  mention  that  this  makes  extraction  much  more 
difRcult. 

Bone  Repair  Following  the  Treatment  of  Periapical  Infections. — 
The  roentgen  picture  not  only  serves  to  diagnose  properly  the  extent 
of  the  involvement  of  the  periapical  tissues,  that  is,  the  bone  and 
tooth  root,  but  furnishes  also  a  means  of  checking  up  the  progress 
of  bone  repair  no  matter  whether  the  treatment  was  medicinal,  electro- 
lytic or  surgical.  It  should  be  remembered  that  bone  formation  is 
the  only  thing  shown  and  that  it  takes  from  six  months  to  a  year  for 
healing  to  be  distinctly  noticeable.  One  should  not,  however,  be  too 
optimistic  when  a  change  is  found  in  the  roentgen  picture,  as  a  tem- 
porary improvement  may,  for  some  time,  decrease  the  extent  of  bone 
inlection  but  does  not  necessarily  imply  a  cure.  It  is  also  important 
to  regulate  the  exposure  and  development  so  that  the  two  pictures 
to  be  compared  are  about  the  same  in  these  respects  and  the  contrast, 
density  and  angle  of  exposure  will  be  parallel  in  the  two  films.  If 
healing  is  progressing  properly  bone  bridges  should  be  seen  filling 
the  cavity  in  a  uniform  manner. 

Figs.  730  to  732  show  a  case  in  which  root-canal  treatment  was 
started  in  December,  1916,  under  strictly  aseptic  care.  Ionization  was 
employed  and  the  canal  filled  after  the  treatment  was  completed. 
Fig.  731  shows  the  root-canal  filling  and  progress  of  healing  after  a 
period  of  three  months.     In  December,  1919,  a  new  film  was  taken. 


748       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

This  is  shown  in  Fig.  732  and  reveals  definite  resorption  at  the  apex 
of  the  root,  although  the  abscess  area  at  the  side  of  the  tooth  has 
healed. 


Fig.  730 


Fig.  731 


Fig.  732 


^  T^ 


Fig.  733 


Fig.  734 


Fig.  735 


Fig.  736 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       740 

i\.iiotlier  case  of  periapical  infection,  on  a  lower  second  molar,  is 
shown  in  Fig.  733.  The  pulp  in  this  tooth  had  recently  become  infected. 
It  was  removed  and  the  root  canal  treated  from  May  2  to  May  15, 
1919,  and  filled  on  May  23.  The  condition  at  that  time  is  shown 
in  Fig.  733.  A  new  picture,  taken  March  1,  1920  (Fig.  734),  records 
the  healing  as  it  had  progressed  up  to  that  time. 

After  apicoectomy,  or  root  resection,  the  heahng  process  can  also 
be  checked  up  by  the  roentgen  method.  A  film  should  be  taken 
immediately  after  the  operation  for  use  later  in  comparison.     Fig. 

735  reproduces  a  roentgen  picture  taken  just  after  such  an  operation. 
The  apices  of  the  two  upper  incisors  were  resected  and  the  dark  area 
in  the  bone  around  these  roots  represents  the  size  of  the  cavity.     Fig. 

736  shows  the  same  case  after  two  years.  The  former  abscess  cavity 
had  entirely  filled  in  with  bone. 

Alveolar  Infection. 

Injury  and  infection  of  the  gingivse  and  the  neck  of  a  tooth  causes 
an  inflammatory  condition  which  can  easily  be  recognized  in  the 
mouth  if  careful  examination  be  made.  There  are  a  great  many 
causes  for  gingival  inflammation,  the  chief  one  being  traceable  to  poor 
dentistry  in  such  work  as  fillings,  pooHy  fitting  crowns  and  lack  of 
contact  points  between  the  teeth.  Such  dental  shortcomings  have 
already  been  discussed  in  the  chapter  on  these  subjects.  The  inflam- 
mation next  spreads  to  the  periodontal  membrane  and  attacks  the 
cervical  part  of  the  alveolar  process.  At  this  stage  changes  are 
visible  in  roentgenograms.  At  first  an  irregular  outline  is  seen  on  the 
bone  edge  between  the  teeth ;  later  when  the  disease  spreads  along  the 
root  of  the  tooth,  more  bone  becomes  absorbed,  so  that  a  pus  pocket 
forms  at  the  side  of  the  tooth,  progressing  generally  in  a  vertical 
direction.  On  account  of  the  bone  being  replaced  by  inflammatory 
gi'anulation  tissue  a  picture  of  a  pocket  is  clearly  recorded  in  the 
roentgen  film,  and,  as  a  rule,  the  cause  is  also  discernible.  Inter- 
radicular  infection  sometimes  results  from  cervical  infection  of  the 
alveolar  process,  the  disease  spi-eading  to  the  alveolar  septum  betw^een 
the  roots  of  a  multi-rooted  tooth,  often  forming  an  abscess,  which 
closely  resembles  clinically  any  of  the  stages  of  an  acute  alveolar 
abscess,  due  to  disease  of  the  dental  pulp.  The  roentgen  picture, 
therefore,  is  an  important  means  of  differential  diagnosis.  Fig.  737 
shows  a  pocket  on  both  the  mesial  and  distal  sides  of  the  first  bicuspid, 
caused  by  a  poorly  fitting  gold  crown.  Fig.  738  reveals  a  large  pocket 
between  the  second  bicuspid  and  molar.  The  space  between  these  two 
teeth  was  constantly  filled  with  stagnant  food.      In  Fig.  739  another 


750       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

large  pocket  between  two  molars  is  shown.  This  condition  was 
probably  caused  by  lack  of  contact  between  the  two  teeth.  Fig.  740 
illustrates  a  case  in  which  there  was  a  pocket  between  the  two  molars 


Fig.  737 


Fig.  738 


Fig.  739 


*  4 


Fig.  740 


Fig.  741 


Fig.  742 


Fig.  743 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DLSEASES       751 

in  the  lower  jaw.  The  contour  of  the  gold  crown  on  the  molar  was 
not  sufficiently  built  out  to  close  the  space.  In  Fig.  741  the  cause  of 
a  pocket  between  a  bicuspid  and  molar  is  seen  to  be  due  to  an  over- 
hanging gold  crown  and  also  to  some  excess  filling  material  which  was 
left  between  the  gold  crown  and  the  distal  side  of  the  bicuspid.  In 
Fig.  742  an  inter-radicular  abscess  appears  on  a  lower  molar.  It  was 
caused  by  a  pus  pocket  and  inflammation  of  the  gum  at  the  buccal 
side.  Fig.  743  also  shows  an  inter-radicular  abscess.  The  dark  area 
between  the  roots  indicates  the  abscess,  which  has  replaced  the  bone 
of  the  alveolar  septum,  and  at  the  inner  surface  of  the  roots  deposit 
of  serumal  calculus  can  be  seen,  which  leads  to  the  conclusion  that 
the  condition  has  existed  for  a  considerable  time. 

Pyorrhea  Alveolaris. — Pyorrhea  alveolaris  can  be  demonstrated 
roentgenographically  just  as  soon  as  the  bone  becomes  involved.  If 
one  roentgen  picture  of  only  part  of  the  mouth  is  examined  and  an 
occasional  pus  pocket  is  found  a  diagnosis  of  pyorrhea  should  never 
be  made,  as  this  may  be  due  to  some  local  traumatic  cause.  It  is 
necessary  to  have  clinical  confirmation  of  roentgen  diagnosis  of 
alveolar  infection  and  pus  pockets  on  most  of  the  teeth,  as  pyorrhea 
is  not  a  disease  which  confines  itself  to  one  part  of  the  mouth.  Roent- 
gen evidence  is  especially  valuable  to  show  the  extent  of  the  disease 
an,d  the  amount  of  bony  support  which  remains  to  hold  the  teeth 
firmly  in  place.  In  the  early  stages  we  see  only  an  irregular  outline 
at  the  alveolar  margin,  the  compact  part  having  been  destroyed,  so 
that  the  outline  of  the  bone  between  the  teeth  is  irregular  and  has 
a  spongy  appearance.  Later  the  stratum  durum,  the  cortical  part 
of  the  alveolar  socket,  becomes  dissolved  and  a  wider  space  than  is 
normally  occupied  by  the  peridental  membrane  can  be  seen  between 
the  tooth  and  bone.  More  and  more  of  the  bone  is  then  destroyed 
and  regular  pockets  form.  In  cases  of  very  long  standing  w^e  may 
find  places  where  the  entire  alveolar  socket  has  disappeared,  leaving 
a  funnel-shaped  pocket,  the  alveolar  bone  between  the  teeth  often 
being  entirely  destroyed,  so  that  finally  the  teeth  are  only  supported 
by  the  gum  and  consequently  become  extremely  loose.  At  this  stage 
a  pulpitis  usually  sets  in,  sometimes  causing  an  acute  alveolar  abscess. 
The  cementum  of  the  tooth  not  only  becomes  pus-soaked,  but  also  is 
covered  with  scales  of  serumal  calculus,  which  can  easily  be  discerned 
in  a  good  roentgen  film.  The  roentgenogram  reveals  principally 
pockets  at  the  sides  of  the  teeth,  and,  while  these  may  be  extremely 
deep,  there  may  be  sufficient  bone  lingually  and  buccally  to  support 
the  tooth,  so  that  it  appears  very  firm.  On  the  other  hand  large 
pockets  may  exist  at  the  labial  and  lingual  surfaces  when  the  roentgen 
picture  shows  normal  bone  at  the  mesial  and  distal  sides. 


752       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


The  illustrations  are  all  of  one  part  of  the  mouth,  showing  various 
degrees  of  pyorrhea.     The  same  condition  could  be  demonstrated 


Fig.  744 


Fig.  745 


Fig.  746 


Fig.  747 


Fig.  748 


Fig.  749 


Fig.  750/' 


Fig.  751 


on  other  teeth.    Fig.  744  shows  a  case  in  which  there  was  a  perfectly 
normal  condition  of  the  alveolar  process.    Note  the  normal  peridental 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       753 

membrane,  the  stratum  durum  lining  the  alveolar  sockets  and  con- 
tinuing as  a  dense  layer  of  bone  at  the  alveolar  margin  between  the 
teeth.  Fig.  745  shows  a  case  in  which  the  bone  has  just  started  to 
become  involved.  Figs.  746  and  747  both  show  loss  of  bone  between 
the  teeth.  The  marginal  part  of  the  alveolar  bone  shows  a  spongy, 
irregular  appearance,  but  no  deep  pockets  have  been  formed.  Figs. 
748  and  749  are  two  cases  in  which  the  pockets  have  formed  at  the 
sides  of  the  teeth,  indicated  by  the  dark,  wedge-shaped  spaces  along 
the  roots.  Fig.  750  shows  an  extreme  case  in  which  extensive  bone 
destruction  has  occurred  around  the  mesial  root  of  the  first  molar. 
The  inter-radicular  septum  of  the  tooth  has  also  been  entirely  lost. 
The  pulp  is  probably  infected  and  calcareous  deposits  are  seen  at 
the  distal  side  of  the  first  bicuspid  and  on  the  molar  roots.  Fig.  751 
shows  the  lower  incisors  of  a  pyorrhea  case,  with  large  deposit  of 
salivary  calculus  at  the  alveolar  margin. 

Bone  Infection. 

If  we  consider  the  frequency  of  dental  infections  it  is  surpris- 
ing how  rarely  we  find  very  extensive  bone  infection  and  serious 
involvement  of  the  adjoining  structures  and  the  alveolar  process. 
The  reason  for  this  is  probably  to  be  found  in  the  bountiful  blood 
supply  of  the  bone  in  the  immediate  neighborhood  of  the  roots 
of  each  tooth,  from  which  a  defensive  system  is  built  up  to  prevent 
the  spreading  of  infection,  carrying  away  the  products  of  bacterial 
activity  so  successfully  that  there  is  but  seldom  an  outlet  or  fistula 
formed  to  the  face  or  gum.  Peridental  infections  sometimes  result 
in  extensive  lesions  of  the  jaw,  as  well  as  radicular  or  periodontal  cysts, 
which  are  also  of  the  infectious  type.  It  is  a  deplorable  fact  that 
they  are  generally  not  recognized  for  a  long  time  and  the  general 
practitioner  of  dentistry  often  treats  devitalized  teeth  associated 
with  large  bone  infections  for  months  by  means  of  root-canal  medica- 
tion without  making  an  accurate  diagnosis,  and,  therefore,  the  jaws 
are  frequently  seriously  involved  when  the  patient  finally  consults  a 
roentgenologist  or  oral  surgeon.  Every  operator  should  be  familiar 
with  various  types  of  bone  infection  and  recognize  them  clinically  and 
roentgenographically. 

Diffuse  Osteomyelitis. — Diffuse  osteomyelitis  of  the  jaws  is,  for- 
tunately, a  rare  occurrence.  The  author  has  seen  only  five  typical 
cases  during  the  past  five  years.  One,  in  the  upper  jaw,  healed  rapidly 
after  the  removal  of  several  sequestra.  The  other  four,  occurring  in 
the  mandible,  were  much  more  serious.  In  one  case  there  was  spon- 
taneous fracture  at  the  angle  of  the  jaw  before  the  patient  noticed 
48 


754       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

any  diseased  condition.  In  all  of  these  cases  the  disease  was  very 
stubborn,  new  sequestra  formed  continually,  involvement  of  formerly 
unaffected  parts  could  not  be  prevented  and  with  the  best  of  care  it 
took  months  for  complete  recovery. 


Fig.  752 


Fig.  753 


For  comparison,  Fig.  752  shows  the  anterior  part  of  an  entirely 
normal  upper  jaw.  Fig.  753  reveals  a  blind  abscess,  or  granuloma,  on  a 
devitalized  central  incisor.  In  diffuse  osteomyelitis  we  find  roentgeno- 
graphically,  at  first,  a  rarefied  condition  in  the  entire  cancellous  part 


■ 

■ 

1 

■ 

W 

m 

K 

^P 

KIm 

F 

9Hi 

i 

] 

•j 

1 

4 

i 

Fig.  754 


Fig.  755 


of  the  jaw.  This  is  due  to  changes  caused  by  infection  in  the  marrow 
spaces.  Figs.  754  and  760  show  the  typical  appearance  of  the  first 
stage  of  the  disease.  Later  necrosis  sets  in,  sequestra  are  formed,  and, 
in  the  roentgen  picture,  channels  are  seen  which  can  be  compared  with 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       755 

the  appearance  of  worm-eaten  wood.  Fig.  755  shows  a  case  of  osteo- 
myeUtis  with  bone  necrosis  in  the  upper  jaw.  The  patient,  a  girl, 
aged  nineteen  years,  complained  that  her  mouth  had  been  feeling 
sore  for  about  eight  months,  although  two  teeth  had  been  extracted 
and  replaced  by  a  bridge.  The  bridge  was  later  taken  off  and  the 
gum  lanced  without  giving  relief.  When  the  patient  was  presented 
for  consultation  a  roentgen  picture  was  taken  at  once,  which  showed 
a  typical  case  of  osteomyelitis  with  bone  necrosis.  When  operated 
upon  a  large  sequestrum  was  found  loose  and  removed  with  the 
left  upper  central  incisor  and  first  bicuspid  attached  to  it.  There 
were  also  two  other  bone  sequestra  found.  The  healing  progressed 
quickly  and  without  complication.  Another  case  is  shown  in  Fig. 
761,  the  earlier  stage  of  which  appears  in  Fig.  760.     The  patient,  Mrs. 


Fig.  756 


Fig.  757 


L.,  had  been  in  perfect  health.  On  December  24,  1915,  she  had  a 
tooth  "capped"  by  her  dentist.  December  26  the  tooth  was  extracted 
by  another  dentist  on  account  of  an  abscess.  December  28  the 
patient  went  to  the  hospital  and  received  palliative  treatment.  On 
January  18,  1916,  she  complained  of  pain  in  the  entire  lower  jaw, 
inability  to  open  her  mouth  and  soreness  of  the  teeth.  Temperature, 
99.5°  F.  Examination  revealed  that  the  only  teeth  of  the  mandible 
present  were  the  front  ones  from  the  left  lower  first  molar  to  the  right 
lower  second  bicuspid.  All  these  teeth  were  extremely  loose  and 
there  was  evidence  of  the  right  lower  first  molar  having  recently  been 
extracted.  All  the  remaining  upper  teeth  were  firm  and  in  good 
condition.  At  first  the  roentgen  plates  showed  only  a  rarefied  area 
extending  from  one   side  of  the  mandible  to  the  other.     Surgical 


756        ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 

treatment  was  started  at  once  and  several  sequestra  removed.  The 
disease  spread  as  far  as  the  angle  of  the  jaw  on  the  left  side,  when, 
on  March  2,  the  roentgen  picture  showed  the  more  advanced  stage 
seen  in  Fig.  761. 

Ostitis. — This  is  a  bone  infection  of  a  more  extensive  type,  developing 
often  from  periapical  infections.  It  may  be  of  the  suppurative  type, 
accompanied  by  violent  acute  symptoms,  but  more  often  is  of  a  chronic 
character,  developing  from  chronic  periapical  infection.  This  type 
is  called  granulating  ostitis.  It  may  involve  large  portions  of  the 
jaw  and  several  teeth  without  causing  much  swelling  or  pain.  A  fistula 
is  seldom  formed,  and  when  it  does  occur  is  due  to  an  exacerbation 
causing  more  active  pus  formation.  It  may  lead  to  the  nose,  the 
mouth,  the  outside  of  the  face  or  the  maxillary  sinuses.     The  roentgen 


Fig.  758 


Fig.  759 


picture  shows  an  area  of  dark  appearance,  usually  of  irregular  outline, 
with  very  indistinct  margins,  due  to  a  gradual  change  from  healthy  to 
diseased  tissue.  Fig.  756  shows  a  case  of  gtanulating  ostitis  of  large 
dimensions.  Compare  this  picture  with  Figs.  752  to  759  and  note 
the  difference  in  the  general  appearance  and  outline. 

Radicular  or  Periodontal  Cysts. — The  radicular  cyst  is  of  inflam- 
matory, infectious  origin  and  is  developed  from  a  blind  abscess,  or 
granuloma,  a  chronic  inflammatory  lesion  M^hich  forms  at  the  apex 
of  an  infected  tooth.  Epithelial  rests,  remnants  from  the  enamel 
organ,  are  frequently  found  in  the  normal  peridental  membrane  and, 
through  irritating  influences,  such  as  those  exerted  by  chronic  inflam- 
mation, these  are  caused  to  proliferate,  forming  chains  of  epithelium 
which  grow  like  a  network  through  the  lesion.     Having  a  tendency 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       757 

to  grow  between  vital  and  necrosed  tissue  the  epithelium  soon  forms 
an  entire  lining  of  the  abscess  cavity.  Accumulation  of  broken-down 
tissue  and  exudates  causes  extension  of  the  cyst.  It  often  grows  to 
tremendous  size  at  the  expense  of  the  bone,  which  disappears  through 
pressure  absorption.  The  bone  may  become  so  thin  that  a  cracking 
sound  can  easily  be  heard  on  palpation.  In  the  upper  jaw  cysts  may 
encroach  on  the  nasal  cavity  or  develop  inside  the  maxillary  sinus, 
sometimes  filling  it  almost  completely,  a  condition  which  is  very 
difficult  to  diagnose.  In  the  lower  jaw  they  are  found  in  the  body 
of  the  mandible  as  well  as  in  the  ramus.  Radicular  cysts  sometimes 
have  apparently  no  connection  with  a  tooth  root.     In  such  cases  the 


Fig.  760 


guilty  tooth  may  have  been  extracted,  the  cyst  having  escaped  notice 
at  the  time,  or  there  may  have  been  left  in  the  jaw  an  epitheliated 
granuloma,  which  developed  into  a  cyst  later. 

Just  how  long  cysts  remain  unnoticed  depends  a  great  deal  on  their 
location  and  rapidity  of  growth  and  upon  accidental  changes  in  the 
pathologic  development.  Symptoms  may  appear  as  changes  in  the 
facial  contour,  such  as  swellings  on  the  cheek  or  side  of  the  mandible, 
on  the  hard  palate  or  under  the  lip.  Distention  of  the  cyst  is  often 
evidenced  by  indefinable  obscure  pressure  and  occasionally  causes 
displacement  of  some  of  the  teeth.  Pain  is  extremely  rare,  but  in 
two  cases  I  have  seen  complete  paresthesia  of  the  lower  lip,  due  to 


758       ROENTGEN  DIAGNOSIS  IN  OPERATIVE  DENTISTRY 


Fig.  761 


SPECIAL  ROENTGEN  STUDY  OF  DENTAL  DISEASES       759 

involvement  of  the  inferior  alveolar  nerve,  A  cyst  with  an  opening 
into  the  mouth  is  noticed  by  the  discharge  of  its  excretion,  which 
causes  a  bad  taste  and  a  disagreeable  odor  in  the  mouth.  Secondary 
infection,  which  occurs  through  the  diseased  pulp  canal  or  pus  pocket 
of  an  adjacent  tooth  frequently  causes  symptoms  of  acute  or  sub- 
acute dental  abscesses  and,  subsiding,  may  leave  a  fistula  on  the 
gum,  which  often  leads  to  faulty  treatment. 

The  diagnosis  of  a  cyst  is  easily  made  by  means  of  the  roentgen 
ray.  The  roentgen  examination  should  be  made  on  large  films  or 
plates,  as  the  small  ones  seldom  cover  more  than  part  of  the  lesion. 
The  cyst  cavity  appears  as  a  black  area  on  the  negative,  because  it 
decreases  the  resistance  which  in  normal  bone  conditions  is  put  in 
the  way  of  the  rays.  The  bone  immediately  surrounding  the  cavity, 
however,  is  usually  cortical  and  dense  and  so  we  find  the  typical 
picture  of  a  cyst  showing  a  light,  but  distinct,  surrounding  line,  well 
illustrated  in  Figs.  758,  759  and  762.  In  case  of  cysts  the  roentgen 
picture  is  also  an  aid  in  making  a  differential  diagnosis  as  well  as  to 
give  exact  information  regarding  the  shape,  size  and  location  of  the 
lesion.  It  shows  its  relation  to  important  neighboring  structures,  such 
as  the  inferior  alveolar  nerve,  the  maxillary  sinus  and  the  nose.  It 
will  show  the  number  of  teeth  involved  and  be  a  valuable  guide  for 
the  operative  technic. 


INDEX. 


Abnormal  dentition,  diagnosis  of,  705 
Abscess,  pericemental,  573 
Alloys  for  amalgam     See  Amalgam, 
for  plates  and  solders.     See  Gold, 
of  gold,  347-349 
Alveolectomy,  external,  642 

modified,  643 
Amalgam,  349 

annealing  of,  363 
buying  of,  377 
chemical  relations  of,  375 
classes  of,  353-354 
classification  of,  377 
composition  of,  352-360,  361 
contraction  of,  356-363 
copper,  375 

expansion  of,  356-363,  365 
fillings  of,  241 
flow  of,  372 
keeping  of,  377 
manipulation  of,  379-386 
nature  of,  349 
pluggers  for,  245 
preparation  of  cavity  for,  241 
properties  of,  349 
strength  of,  355,  366 
thermal  relations  of,  375 
washing  of,  374 
Anatomy,  surgical,  588,  589 

of  teeth,  24-39 
Anemia,  502 

Anesthesia  for  dentin,  522 
injection  for,  514 

at  incisive  foramen,  518 

at  infra-orbital  foramen,  516 

at  mandibular  foramen,  519 

at  maxillary  tuberosity,  517 

at  mental  foramen,  521 

at  posterior  palatine  foramen, 

518 
subperiosteal,  514 
local,  498 

agents  for,  503-510 
areas  anesthetized,  517-526 
armamentarium  for,  510 
conduction,  499-514 
for  operations  other  than  ex- 
tractions and  pulp  removal, 
524 
history  of,  498 


Anesthesia,  local,  means  of  producing, 
499 
physiologic  action  of,  500 
places  for  injection,  517-526 
for  pulps  of  teeth,  521 
technic  of,  514 
terminal,  499-514 
for  pulp,  521-524 

injections  for,  521 
Anesthetics  for  sensitive  dentin,  463 
Angina,  Vincent'^,  575 
Annealing  of  alloys,  363 

of  gold,  343 
Antisepsis  in  root-canal  operations.  442 
Antiseptic   cements.     See   Copper   oxy- 

phosphates. 
Antiseptics,  177 
Apical  foramen,  filling  of,  445 
Apicoectomy,  646 

indications    and    contra-indications 

for,  646 
technic  of,  649 
Arches,  dental,  relationships  of,  55-57 

shapes  of,  53 
Arthritis,  125 
Articulation  of  teeth,  23 
Atmospheric  pressure,  occlusion  of  teeth 

and,  667 
Atrophy,  senile,  580 

of  teeth,  23 
Attachments  for  bridges,  284-298 
Auto -intoxication,  551 


B 


Bacteria,  547 
Bicuspids,  canals  of,  444 

extraction  of,  596,  603 
Bleaching  of  teeth,  473 

cataphoresis  in,  490 

chlorine  in,  475 

dioxid  of  hydrogen  in,  475 
of  sodium  in,  475 

Harlan's  method  of,  487 

iodine  in,  475 

light  in,  493 

McQuillan's  method  of,  487 

sulfur  dioxid  in,  475 

Truman's  method  of,  480 
Bloodvessels  of  peridental  membrane,  117 
of  pulp,  92-93 

(761) 


762 


INDEX 


Bridge  attachments,  284-298 

preparation  of  cavities  for,  284- 
298 
Brushes,  tooth,  171 

how  to  use,  173-174 
Burnishers,  316,  317,  319 
Burs,  183 

fissure,  183 
inverted  cones,  183 
l^ound,  183 
tapered,  183 


Calcification  of  teeth.  See  An  atomy  of. 
Calcuh,  153-154,  545 
diagnosis  of,  678 
Canals,  root,  preparation  and  filHng  of, 
431-453 
,  treatment  of,  411 
Canines,  anatomy  of  deciduous  series,  54 

of  permanent  series,  28,  42 
Caries,  diagnosis  of,  717 
prevention  of,  134 
susceptibility  to,  188 
Casting  of  gold  inlays,  278-281 
Cataphoresis  in  bleaching  of  teeth,  490 
Cavities,  classification  of,  196 

class  I,  preparation  and  filling 
of,  198 

II,  preparation  and  filling 
of,  204 

III,  preparation  and  filling 
of,  210 

IV,  preparation  and  filling 
of,  213 

V,  preparation  and  filling 
of,  217 

filling  of,  164. 

preparation  of,  instruments  for,  182 
for  porcelain  inlays,  instruments 

for,  300 
system  of,  187 

for  amalgam,  241 

for     bridge     attachments, 

284-298 
for  cements,  252 
for  gold  foil,  187-218 

inlays,  261-284 
for  gutta  percha,  249 
for  porcelain  inlays,  299 
tapered,  284-298 
Cell  activity,  occlusion  of  teeth  and,  664 
Cement,  fillings  of,  252 
Cementation  of  gold  inlays,  282 
of  porcelain  inlays,  334-338 
Cementoblasts,  106 
Cements  386 

copper  oxy phosphates,  390 
germicidal.     See   Copper   oxyphos- 

phates. 
mixing  of,  400 
preparation  of  cavities  for,  252 


Cements,  properties  of,  386 ,  396-400 

silicate,  252,  254,  338,  395 

silver.     See  Copper  oxj^hosphates. 

zinc  oxyphosphates,  387-388 
Cementum,  exostosis  of,  98 

formation  of,  96 

fimction  of,  95 

hypertrophies  of,  98 

nature  of,  95 

structure  of,  96-97 
Charts,  roentgenogram,  495 
Chemicals  for  root-canal  treatment,  411- 

414 
Children's  teeth,  filling  of,  255-312 
Chlorapercha,  449 
Chlorine  in  bleaching  of  teeth,  475 

use  of,  in  root  canals,  416 
Clamps,  rubber  dam,  187-217 
Cocaine,  506 

Concretions,  removal  of,  153 
Conduction  anesthesia,  499-514 
Conductivity  of  gold,  346 
Contact,  proximate,  165 
Contours,  165 

Contraction  of  amalgam,  356-363 
Copper  amalgam,  375 

oxyphosphates,  390 

liquid  portion      See  Zinc  oxy- 
phosphates. 
powder  portion,  390 
Cresol-formalin,  use  of,  in  root  canals,  415 
Cuspids,  canals  of,  444 

extraction  of,  595,  603 
Cysts,  diagnosis  of,  713-756 


Deciduous  teeth,  23,  54 
extraction  of,  606 
filling  of,  255 
Deglutition,  occlusion  of  teeth  and,  666 
Dental  floss,  175 
Dentifrices,  175 
Dentin,  81 

anesthesia  for,  522 

composition  of,  81 

derivation  of,  81 

granular  layer  of  Tomes,  85,  88,  89, 

97 
hypersensitive,  454 
pathology  of,  454 
symptoms  of,  458 
treatment  of,  458 
innervation  of,  454 
interglobular  spaces  of,  86 
junction  of,  with  enamel,  86 
matrix  of,  82 
structural  elements  of,  82 
tubuli  of,  82-91 
direction  of,  84 
Dentistry,  operative,  description  of,  179 
preventive,  description  of,  122-127 


INDEX 


763 


Dentition,  abnormal,  diagnosis  of,  705 
Devitalized  teeth,  698 

retention  of,  699 
Diabetes  mellitus,  550 
Diagnosis.     See  Roentgen  diagnosis. 
Dichloramin-T,  use  of,  in  root  canals,  416 
Diets,  141 

Dioxid  of  hydrogen  in  bleaching  of  teeth, 
475 
of  sodium  in  bleaching  of  teeth,  475 
Disclosing  solution,  161 
Discoloration  of  teeth,  467 

causes  of,  467 

rationale  of  process,  469 

special,  495 

treatment  of,  467 

which  can  be  removed,  473 
Ductility  of  gold,  341  ■ 


E 


Electrolysis,  use  of,  in  root  canals,  419- 
422 

Enamel  margins,  195 
of  teeth,  63 

cementing  substance  of,  65 
cleavage  of,  69 
composition  of,  64 
derivation  of,  63 
incremental  lines  of,  74 
rods  of,  65 

direction  of,  72,  194 
stratification  bands  of,  73 
strength  of,  requirements  for,  75 
structural  element  of,  65 

Endocarditis,  125 

Endosmosis,  electric,  for  sensitive  den- 
tin, 464 

Ethyl  chlorid,  503 

Eucapercha,  261 

Exostosis,  98 

Expansion  of  amalgam,  356-363,  365 
of  gold,  344 

Expression,  occlusion  of  teeth  and,  667 

Extension  for  prevention,  137,  188 

Extirpation  of  pulps  of  teeth,  723 

Extraction  of  teeth,  588-642 
accidents  during,  621 
bicuspids,  596,  603 
contra-indications  for,  591 
cuspids,  595,  603 
deciduous,  606 
hemorrhage  following,  626 
impacted,  630,  637 
incisors,  593,  594,  602 
indications  for,  591 
instruments  for,  608-641 
management  of  patient  for,  592 
molars,  598-600,  604,  637 
pathology  involved  in,  634 
post-operative  pains  in,  629 

treatment  in,  628-640 
pre-operative  treatment  in,  628 


Extraction  of  teeth,  roots,  607 
supernumerary,  607 
unerupted,  630,  637 


Files  for  finishing,  238 
Filling  of  apical  foramen,  445 

materials,  properties  of,  339 

of  pulp  chambers,  zinc  oxychlorid 

for,  482 
of  root  canals,  431-453 
Fillings  of  amalgam,  241 
of  cement,  252 
finishing  of,  237 
of  gold,  218 
of  gutta-percha,  249 
of  inlays,  261-299 
radiolucency  of,  719 
Fihns,  160 

for  roentgenograms,  679-683 
development  of,  684 
Finishing  fillings,  237 
files  for,  238 
of  gold  inlays,  281 
knives  for,  238 
saw  for,  238 
strips  for,  240 
Fissure  burs,  183 
Floss,  dental,  175 
Forms  of  teeth,  diversities  in,  22 
Formula  for  alloys  for  amalgam.      See 
Amalgam, 
for  plates  and  solders.     See  Gold. 
Furnaces,  329 
Fusing  of  porcelain  inlays,  317-326 


G 


Germicidal  cements.     See  Copper  oxy- 

phosphates. 
Gingivitis,  ulcerative,  582 
Glycogen  in  saUva,  140 
Gold,  339 

alloys  of,  347-349 

conductivity  of,  346 

ductility  of,  341 

expansion  of,  344 

fillings  of,  218 

foil,  preparations  of  cavities  for,  187- 

218 
hardness  of,  342 
inlays,  261 

as  bridge  attachments,  284-298 
casting  of,  278-281 
cavities  for,  262-270 

conflicting    opinions    con- 
cerning, 284-298 
preparation  of,  261-284 
cementation  of,  282 
finishing  of,  281 
gold  for,  289 


764 


INDEX 


Gold  inlays,  indirect  method  for,  283- 
321,  323 
pattern  for,  271 

investing  of,  274 
removal  of,  277 

malleability  of,  342 

melting-point  of,  340 

oxidation  of,  346 

pluggersfor,  231-233 

preparation  of,  for  fillings,  218 

properties  of,  339 

solubility  of,  346 

specific  gravity  of,  340 

tensile  strength  of,  344 

volatiHty  of,  341 
Granular  layer  of  Tomes,  85,  88,  89,  97 
Gums,  retraction  of,  579 
Gutta-percha,  401,  449 

employment  of,  404 

fillings  of,  249 

preparation  of  cavities  for,  249 

properties  of,  401,  403 

radiolucency  of,  719 

with  other  materials,  410 


H 


Hardness  of  gold,  342 

Harlan's  method  of  bleaching  teeth,  487 

Haversian  canals,  117 

Hemorrhage     following     extraction     of 

teeth,  626 
High-pressure  syringes,  523 
Histology  of  teeth,  59 
Hunter's  "Anathematization  of  Ameri- 
can Dentistry,"  123 
Hygiene  movement,  oral,  138 
Hypersensitive  dentin,  454 

pathology  of,  454 

symptoms  of,  458 

treatment  of,  458 
Hypertrophy,  98 
Hypodermic  syringes,  511,  512 


Impacted  teeth,  diagnosis  of,  710 

extraction  of,  630,  637 
Incisive  foramen,  injection  at,  for  anes- 
thesia, 518 
Incisors,  anatomy  of  deciduous  series,  54 
of  permanent  series,  24,  39 
canals  of,  444 

extraction  of,  593,  594,  602 
Infection,  diagnosis  of,  137,  743,  749 
Infra-orbital  foramen,  injection  at,  for 

anesthesia,  516 
Injection  for  anesthesia,  514 

at  infra-orbital  foramen,  516 
at  incisive  foramen,  518 
at  mandibular  foramen,  519 
at  maxiUary  tuberosity,  517 


Injection  for  anesthesia  at  mental  fora- 
men, 521 
for  other  operations  thanextrac- 

tions  and  pulp  removal,  524 
at  posterior  palatine  foramen, 

518 
of  pulp,  521 
subperiosteal,  514 
Inlays,  fimngs  of,  261,  299 
gold,  261 

as  bridge  attachments,  284-298 
casting  of,  278-281 
cavities  for,  262-270 

conflicting    opinions    con- 
cerning, 284-298 
cementation  of,  282 
finishing  of,  281 
gold  for,  289 
indirect  method  for,  283,  321- 

323 
pattern  for,  271 

investing  of,  274 
removal  of,  277 
porcelain,  299 

cavities  for,  299-314,  336 

preparation  of,  instruments 
for,  300 
cementation  of,  334-338 
colors  of,  332 
furnaces  for,  329 
fusing  of,  317-326 
indirect  method  for,  321 
matrix  for,  314-323 
shading  of,  333 
Instruments  for  cavity  preparation,  182 
chisels,  182 
hatchets,  182 
hoes,  182 

trimmers,  marginal,  182 
for  extraction  of  teeth,  608-641 
for  fillings,  231,  233,  245 
for  finishing  fillings  237-258 
plastic,  250 
sharpening  of,  184 
sterilization  of,  431,  511,  514 
Intestinal  intoxication,  552 
Intoxication,  auto-,  551 

intestinal,  552 
Iodine  in  bleaching  of  teeth,  474 


Knive6  for  finishing,  238 


Light  in  bleaching  of  teeth,  493 

Local  anesthesia,  498.     See  Anesthesia, 

local. 
Lymphatic  system  of  teeth,  58 
Lymphatics  of  peridental  membrane,  119 
of  pulp,  92-93 


INDEX 


765 


M 


McQuillan's  method  of  bleaching  teeth, 

487 
Malleabihty  of  gold,  342 
Mal-occlusion  of  teeth,  668 
etiology  of,  668 
treatment  for,  670 

appliances  and  technic  for 

673 
retention,  674 
time  of,  670 
Mandibular  foramen,  injection  at,   for 

anesthesia,  519 
Mastication,  occlusion  of  teeth  and,  666 
Matrix,  use  of,  242-248 
Maxillary  sinuses,  diseases  of,  diagnosis 
of,  701 
tuberosity,  injection  at,  for    anes- 
thesia, 517 
Melting-point  of  gold,  340 
Mental  foramen,  injection  at,  for  anes- 
thesia, 521 
Mercury,  380 
Mixing  cements,  400 
Molars,  anatomy  of  deciduous  series,  54 
of  permanent  series,  34,  46 

f>Q  rj  o  1  c  of    A.A.A. 

extraction  of,  598-600,  604,  637 
Morphology  of  teeth,  21 
Muscular  action,  occlusion  of  teeth  and, 

665 
Myocarditis,  125 


N 


Necrosis,  diagnosis  of,  731 

Nerve  tissue    of  peridental  m.embrane, 

117-120 
Nervous  system  of  teeth,  57 
Neuralgia,  diagnosis  of,  703 
Nitro-hydrochloric  acid,  use  of,  in  root 

canals,  413 
Novocaine,  509 


O 


Occlusion  of  teeth,  653 

development  of,  655-656 
forces  governing,  663 

atmospheric  pressure, 

667 
attention  and  muscu- 
lar tone,  667 
cell  activity,  664 
deglutition,  666 
expression,  667 
mastication,  666 
muscular  action,  665 
respiration,  666 
nomenclature  and  classification, 

668 
normal,  654 


Occlusion  of  teeth,  traumatic,  544 
Odontoblasts,  89-90.     *S'ee  also  Teeth. 
Operative  dentistry,  description  of,  179 
Oral  hygiene  movement,  138 
prophylaxis,  139-151 
sepsis,  127 
Orthodontia,  principles  of,  653.    See  also 

Occlusion. 
Osteoclasts,  109 
Osteomyelitis,  diagnosis  of,  753 
Ostitis,  diagnosis  of,  756 
Oxidation  of  gold,  346 
Oxyphosphates  of  copper,  390 
liquid  portion,  387 
powder  portion,  390 
of  zinc,  387-388 

liquid  portion,  387 
powder  portion,  388-389 


Pain,  cause  of,  456 

post-operative,  629 

Palatine  foramen,  posterior,  injection  at, 
for  anesthesia,  518 

Paste  polisher,  162 

Patient,  instructions  to,  170 

Pericemental  abscess,  573 

Pericementum,  98 

Peridental  affections,  133 
membrane,  98 

arrangement  of,  99-103 
bloodvessels  of,  117 
cellular  elements  of,  105 
cementoblasts  of,  106 
changes  in  ,  with  age,  121 
epithelial  structure  of,  112-115 
functions  of,  98 
giant  cells  of,  98 
IjTuphatics  of,  119 
nerves  of,  117-120 
osteoclasts  of,  109 
structural  elements  of,  98 

Permanent  teeth,  23,  24 

Pigments,  source  of,  467 

Planing  instruments,  159 

Plaques,  160 

Pluggers  for  amalgam,  245 
for  gold,  231-233 

Pneumococci,  125,  669 

Pockets,  pyorrheal,  169 

Poisons,  systemic,  550 

Polishing  cups,  162 

teeth  and  fillings,  161 

Porcelain  inlays,  299 

cavities  for,  299-314,  336 
preparation  of,  299 

instruments  for,  300 
cementation  of,  334-338 
colors  of,  332 
furnaces  for,  329 
fusing  of,  317-326 
indirect  method  for,  321 


766 


INDEX 


Porcelain  inlays,  matrix  for,  314-323 

shading  of,  333 
Potassium  sodium,  use  of,  in  root  canals, 

412 
Preventive  dentistry,  description  of,  122, 

127 
Prophylaxis,  oral,  139-151 
Pulp,  anesthesia  for,  521-524 

canals,  disease  of,  diagnosis  of,  727, 

730,  731 
cavities  of  teeth,  52,  53 
chambers,  filling  of,  zinc  oxychlorid 

for,  482 
of  teeth,  bloodvessels  of,  92-93 
derivation  of,  89 
enervation  of,  94 
extirpation  of,  723 
function  of,  94 
layer  of  Weil  of,  92 
lymphatics  of,  92-93 
membrana  eboris  of,  89 
nerve  tissue  of,  94 
odontoblasts  of,  89,  90 
structure  of,  89 
sensory,  95 
Pus,  559 
Pyorrhea  alveolaris,  527 

cause  of,  534-542 
definition  of  term,  527 
diagnosis  of,  554,  751 
general  principles  of,  537 
healed  lesions  of,  582 
history  of,  527-534 
operative  procedures  for,  536 
prevention  of,  149 
pockets  of,  169 
treatment  of,  561 


R 


Radiolucency  of  fillings,  719 

of  gutta-percha,  719 
Records  for  root-canal  work,  451 
Respiration,  occlusion  of  teeth  and,  666 
Retraction  of  gums,  579 
Roentgen  diagnosis,  675 

in  abnormal  dentition,  705 

of  abscesses  or  granulomata,  740 

of  bone  repair,  747 

of  caries,  717 

of  cysts,  713-756  _ 

in  diseases  of  maxillary  sinuses, 
701 
of  pulp  canals,  727,  730,  731 

for    impacted    and    unerupted 
teeth,  710 

nomenclature  of,  675 

of  osteomyelitis,  753 

of  ostitis,  756 

of  pulps  of  teeth,  723-727 

of  pyorrhea  alveolaris,  751 

in  root  canal  fillings,  736 

in  somatic  disease,  698 


Roentgen   diagnosis  for  supernumerary 
teeth,  712 
for  trifacial  neuralgia,  703 
Roentgenogram,  675 
angle  of  rays,  679 
exposure  for,  683 
development  of  films,  684 
interpretation  of,  688 
mounting  of,  695 
production  of  rays,  676 
recording  of,  695 
tubes  for,  677 

use  of,  in  root-canal  work,  446 
Roentgenology,  675 
Root  canals,  431 

preparation  and  filling,  431-453 

equipment  for,  431-442 
treatment  of,  411 
chemical,  411 
electric,  419-430 
therapeutic,  414 
fillings,  making  of.    See  Root  canals, 
removal  of,  451 
Roots  of  teeth,  arrangement  of,  52,  53 

extraction  of,  607 
Round  burs,  183 

Rubber  dam,  application  of,  185,  443 
clamps,  187,  217 


Saliva,  glycogen  in,  140 

sulphocyanate  in,  140 
Saw  for  finishing,  238 
Scalers,  156,  157,  158 
Sedatives  for  sensitive  dentin,  463 
Senile  atrophy,  580 
Separators,  210 
Sepsis,  oral,  127 
Shading  of  inlays,  333 
Silicate  cements,  395 
Silver  cements.     See  Copper  oxyphos- 

phates. 
Solubility  of  gold,  346 
Specific  gravity  of  gold,  340 
Stains,  160 

Staphylococci,  125,  669 
Sterilization  of  instruments,  431,  511-514 

of  root  canals,  411,  414,  427 
Streptococci,  125 
Stresses,  amount  of,  in  mastication,  180 

relief  of,  168 
Subperiosteal  injection  for  anesthesia, 5 14 
Sulci,  protection  of,  170 
Sulfur  dioxid  in  bleaching  of  teeth,  475 
Sulphocyanate  in  saliva,  140 
Sulphuric  acid,  use  of,  in  root  canals,  413 
Supernumerary  teeth,  diagnosis  of,  712 

extraction  of,  607 
Suprarenal  capsule,  504 
Surgeon's  knot,  187 
Surgery,  558 

extraction  of  teeth,  558-642 


INDEX 


767 


Surgery,  other  surgical  procedures,  642- 

652 
Syringes,  high-pressure,  523 
hypodermic,  511,  512 


Tapered  burs,  183 
Teeth,  17 

anatomy  of  deciduous,  54 
calcification  of,  55 
canines,  54 
incisors,  54 
molars,  first,  54 
second,  54 
occlusal  surfaces  of,  55 
permanent,  mandibular,  39 
canines,  42 
incisors,  first,  43 

second,  45 
molars,  first,  46 
second,  49 
third,  50 
premolars,  first,  43 
second,  45 
maxillary,  24 
canines,  28 
incisors,  first,  24 

second,  26 
molars,  first,  34 
second,  36 
third,  38 
premolars,  first,  30 
second,  32 
arches  of,  dental,  shape  of,  53 
articulation  of,  23 
atrophy  of,  with  age,  23 
bleaching  of,  473 

cataphoresis  in,  490 

chlorine  in,  475 

dioxid  of  hydrogen  in,  475 

of  sodium  in,  475 
Harlan's  method  of,  487 
iodine  in,  475 

McQuillan's  method  of,  487 
sulfur  dioxid  in,  475 
Truman's  method  of,  480 
calcification  of.     See  Anatomy  of. 
canines,  19 

mandibular,  19 
maxillary,  19 
cementum  of,  exostosis  of,  98 
formation  of,  96 
function  of,  95 
hypertrophies  of,  98 
nature  of,  95 
structure  of,  96-97 
dentin  of,  composition  of,  81 

granular  layer  of  Tomes,  85,  88, 

89,  97 
interglobular  spaces  of,  86 
junction  of,  with  enamel,  86 
matrix  of,  82 


Teeth,  dentin  of,  structural  elements  of, 
82 
tubuli  of,  82-91 

direction  of,  84 
devitahzed,  698 

retention  of,  699 
discoloration  of,  467 
causes  of,  467 
rationale  of  process,  469 
special;  495 
treatment  of,  467 
which  can  be  removed,  473 
diversities  in  shape  of,  22 
enamel  of,  cementing  substance  of, 
65 
cleavage  of,  69 
composition  of,  64 
derivation  of,  63 
incremental  lines  of,  74 
rods  of,  65 

direction  of,  72 
stratification  bands  of,  73 
strength  of,  requirements  for, 75 
structural  elements  of,  65 
extraction  of,  588-642 
accidents  during,  621 
bicuspids,  596,  603 
contra-indications  for,  591 
cuspids,  595,  603 
deciduous,  606 
hemorrhage  following,  626 
impacted,  630,  637 
incisors,  593,  594,  602 
indications  for,  589 
instruments  for,  608-641 
management  of  patient  for,  592 
molars,  598-600,  604,  637 
pathology  involved  in,  634 
post-operative  pains  in,  629 

treatment  in,  628,  640 
pre-operative  treatment  in,  628 
roots,  607 

supernumerary,  607 
unerupted,  630,  637 
genesis  of,  59 
histology  of,  59 
impacted,  diagnosis  of,  710 
extraction  of,  630,  637 
incisors,  first  and  second,  18 

central  and  lateral,  18 
mandibular,  18 
maxillary,  18 
lymphatic  system  of,  58 
mal-occlusion  of,  668 
etiology  of,  668 
treatment  of,  670 

appliances  and  technic  for, 

673 
retention,  674 
time  of,  670 
mammalian  formula  of,  20 
molars,  first,  second,  third,  20 
deciduous,  20 
permanent,  20 


768 


INDEX 


Teeth,  morphology  of,  21 
nervous  system  of,  57 
occlusion  of,  653 

classification  of,  668 
development  of,  655 
forces  governing,  663 

atmospheric  pressure, 

667 
attention,  667 
cell  activity,  664 
deglutition,  666 
expression,  667 
mastication,  666 
muscular  action,  665 

tone,  667 
respiration,  666 
nomenclature  of,  668 
normal,  654 
peridental  membrane  of,  98 

arrangement  of,  99-103 
bloodvessels  of,  117 
cellular  elements  of,  105 
cementoblasts  of,  106 
changes  in,  with  age,  121 
epithelial     structures     of, 

112-115 
functions  of,  98 
giant  cells  of,  98 
lymphatics  of,  119 
nerves  of,  117-120 
osteoclasts  of,  109 
structural  elements  of,  98 
premolars,  first  and  second,  19 

known  as  bicuspids,  19 
mandibular,  20 
pulp  of,  bloodvessels  of,  92-93 
cavities  of,  52-53 
enervation  of,  94 
extirpation  of,  723 
function  of,  94 
sensory,  95 
layer  of  Weil  of,  92 
lymphatics  of,  92-93 
membrana  eboris  of,  89 
nerve  tissue  of,  94 
odontoblasts  of,  89,  90 
structure  of,  89 
roots  of,  arrangement  of,  52-53 
succession  of,  23 

deciduous  or  milk,  23 
permanent,  23 


Teeth,  supernumerary,  diagnosis  of,  712 
extraction  of,  607 

types  of,  166 

unerupted,  diagnosis  of,  710 
extraction  of,  630,  637 

vascular  system  of,  57 
Tensile  strength  of  gold,  344 
Terminal  anestliesia,  499-514 
Therapeutics  of  root-canal  treatment,414 
Tomes,  granular  layer  of,  85,  88,  89,  97 
Tooth  brushes,  171 

how  to  use,  173-174 
Traumatic  occlusion,  544 
Traumatism,  580-543 

diagnosis  of,  716 
Trifacial  analysis,  diagnosis  of,  703 
Truman's  method  of  bleaching  teeth,  480 
Tubuli  of  dentin,  82,  91.     See  also  Teeth. 


U 


Ulcerative  gingivitis,  582 
Unerupted  teeth,  diagnosis  of,  710 
extraction  of,  630,  637 


Vascular  system  of  teeth,  57 
Vincent's  angina,  575 
Volatility  of  gold ,  341 


W 


Wadelstaedt  tie,  187 


X-RAYS.     See  Roentgenogram. 


Zinc  oxychlorid  for  filling    pulp  cham- 
bers, 482 
oxyphosphates,  387-388 
liquid  portion,  387 
powder  portion,  388-389 


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